Back Bay Sit On Top Kayak

A Modular System Approach to SOT Kayak Sailing, Paddling and Mirage Drive Propulsion

BB Scorpion bow obl 8 w

Sit-On-Top (SOT) kayaks are easy boats on which to learn to paddle. They have none of the “get in the coffin and you are about to drown” psychological identity that one finds in the Sit-Inside boats and they’re amazingly adaptable to a wide range of paddling activities. It also doesn’t hurt that they are pretty straightforward boats to rotomold, which makes them very cheap to produce in large numbers.

I didn’t envision just one boat for this niche in the home-built kayak market. Instead, it came to me that there would need to be at least three models that could address the wide-ranging styles of boating interests in this area of the kayak world. The result was a couple of very clean, SOT models at 14’ and 16’ called the Corona and the Back Bay, respectively. The third model was going to be called the Wahoo, as it was specifically designed for the folks who spend a lot of time fishing with their SOT’s. I’ll get to the Wahoo in the next article.

As a canoe and kayak sailor and a guy who had just been out for a test drive on the Hobie Adventure Island, which is based on their 16’ SOT Adventure model, I wanted to offer my own take on what makes for a truly fun and stylish, sailing SOT kayak. The result was that a fully integrated system of component parts was designed for the basic Back Bay. This modular approach allows the Back Bay to go sailing by simply adding a system of light-weight, easily built elements that quickly convert the SOT to a single aka sailing boat called the Scorpion, OR, to a double aka sailing boat with slightly larger ama volume, called the Doubloon. Of the two configurations, the Doubloon is most like the well-known and highly respected, Hobie Adventure Island.

The Corona and the Back Bay are virtually identical models, save for their respective lengths. For the purposes of this article, I’ll focus on the Back Bay version and all the potential add-on systems I’ve incorporated in the design.


BB16 above w

Length overall – 16′
Beam overall main hull – 28″
Depth of hull max – 12”
Weight – 48 lbs. or less
Displacement – 335 lbs.

This boat is built in the S&G style of construction in 4mm marine ply with 6 oz. plain weave fiberglass set in epoxy on the inside and outside of the hull for full laminate sandwich strength. The build process uses external cradles as building supports, ensuring that the hull goes together with minimum hassle when handling the rather slender and longish hull panels. The boat is bulkheaded internally at three key points. These bulkheads create not only integrated strength in the design, but they also cleanly separate the hull cavity into four unique volumes for gear storage and watertight flotation.

The Back Bay can be configured with a large, open tankwell set aft of the cockpit, or built with a watertight, aft hatch cover for internal storage in a conventional kayak style.

Scorpion bow low w

Beam overall – 10′
Weight (est.) – 90 lbs.
Sail Area – 56 sq. ft.
Displacement – 350 lbs.
Draft (board down) – 28″

The Scorpion variant is a Sit-On-Top design for fun sailing, paddling, or Mirage peddling… or all three, as the builder desires. There will be a design for a leeboard mount included in the plans for those who are going to build the boat for sailing. Having the aka gull wing form set well forward permits a full paddle swing arc.  The aka beam connectives to the amas is split into a pair of mounting elements. I did this to make for a stronger, single beam mounting struture. With a single beam design, there is a tendency for the am to want to rotate around the beam, making for a very stressed component that could lead to early failure. By splitting the beam and spreading the mounting points, I have given the structure more resistance to this rotational force, making for a more rigid boat in use. This setup will allow the owner to power sail in light air with both the paddle and the sail providing thrust. With the leeboard swung down for sailing, the owner can do some “power sailing” and utilize the Mirage drive, as well as the sail, in light conditions. The Mirage is capable of boosting boat speed enough that it creates apparent wind over the sail, adding power where there really isn’t enough for sailing alone.

The amas are positioned to optimize capsize resistance when sailing off the wind. The amas do not touch the surface of the water at rest in stable trim and provide only minimal wetted surface drag when underway by paddle or peddle. As soon as the sail is loaded by the breeze, though, the ama on the lee side begins to immerse, firming-up the boat and resisting the heeling moments being generated.

The aft deck can be configured as a watertight hatch with full access to the aft sections of the hull, OR a large, diving tank well with self-draining ports. The cockpit is fitted with self-drain ports under the seat as well as forward, in addition to the daggerboard slot. There is a watertight deck plate just forward of the seat, between the knees of the sailor/paddler to provide secure storage for critical items that may be needed on a routine basis. The foredeck has a watertight hatch cover for bow storage needs.

The rig is a fully battened Dacron sail with two reef points and a multi-section, self-supporting mast which steps into a sealed mast socket in the hull. The mast and boom sections can be aluminum or carbon, as budget permits. The sail choice is open for the customer as long as it can be balanced with the fixed positions for the mast and dagger board. The Cunningham is run to the deck of the gull wing aka to keep the rig on the boat in the event of a capsize.

With 56-sq. ft. of sail on a 90-pound boat, this will be a decently speedy boat without being in over its head all the time in a stiff breeze. I suggest two reef points in the sail to allow for sailing in a wide variety of conditions.

This will be a wet boat at speed, yet there are no worries at all for flooding and sinking, save for a truly nasty trip over a reef that shreds the entire underside of the craft. The bow, cockpit and aft hull volumes are all independent, sealed compartments, as are the ama volumes.

Reentry from a swimming session will be easy with a simple, sling, or rope ladder much like those used by rock climbers, called etriers.

BB Scorpion aft obl 8 wSliding foot pedals in the cockpit control the rudder. The rudder flips-up when it encounters an underwater obstacle, or when beaching, returning, due to bungee tension to the deployed position once past the obstruction.

The boat is constructed in a multichine, marine plywood style with epoxy glass laminates inside and out in a stitch and glue style. Stainless T-Nuts are embedded in the hull deck surface from below to provide a secure set of mounting points for the aka wing. The amas are held in place on the aka tips by large bungees and a notched lock system. This system provides for quick setups on the beach.

You just fit the aka to the foredeck, insert four, 1/4″ threaded stainless screws with comfortable, knobbed grips and screw down the aka wing. The amas slip onto the ends of the aka and you lift the pair of 3/8″ bungees up and over two raised hooks on the aka ends to secure the ama in place. Simple, easily maintained and near foolproof in operation.


Doubloon bow obl 8 w

The Doubloon is the second variation on the central SOT theme of this group of boats. In this design, I am looking to provide a more expansive utility application for the base, Back Bay SOT version. The Doubloon is essentially a solo craft and it carries the same, 56 sq. ft. sail, but the overall potential of the boat is expanded through the use of dual akas and full trampolines on both sides of the Back Bay hull. The rendering of the Doubloon shows a daggerboard inserted down through the Mirage Drive trunk, but in use, I would prefer to have the board mounted outside the Back Bay hull as a leeboard. Plans will be supplied with the leeboard solution.

The akas on the Doubloon are spaced to allow for a full paddle stroke with the boat setup as a trimaran. There are two sections of tubing that span the opening fore and aft between the akas from which the tramp is mounted. The trampolines are designed to roll-up on the outer tube section, much like a window shade and they are deployed by an endless loop of light halyard line. With the tramps fully deployed, the inner tube section lifts up and over a holding pin in the aka and the sailor applies as much tension to the tramp as he feels he needs by hauling-in the endless loop line and cleating it off. If a paddling session is desired, he simply pops the jam cleat and pulls the line to roll-up the tramp on the outer tube section. This procedure applies for both port and starboard tramps.

Like the Scorpion, the Doubloon can be built to utilize a Mirage drive in the center well and the need to roll-up the tramps for paddling is essentially negated, (though it is nice to have the option once in awhile as Mirage drives can be difficult to maneuver in tight places)

The aka beams are held to the deck of the Back Bay hull with the same, threaded knob strategy for quick setup and takedown times. Similarly, the amas are held to the aka ends with hefty bungee cords for the simplicity of use. There’s another, rather invisible, benefit to using the bungee cords for ama mounting. Because they are being held in place through a fairly dynamic hold-down system, the amas can move about, ever so slightly, while underway. This allows the amas to have some structural “give” and the result is that the banging and thrashing that is typically experienced by the ama, is somewhat dissipated through the flex of the joining system.

Doubloon aft obl wThe design similarities to the Hobie Adventure Island are obvious. This boat, however, should be just a bit faster in the water, mostly because it will be much lighter than the rotomolded Hobie. For that same reason, it will also be easier to put it up on a roof rack for transport to the water and a lot easier on the back when you have to take it off the car to store it at home. The Doubloon configuration allows the sailor/paddler/peddler to bring along extra gear, which can be lashed to the tramps in waterproof bags. They can also take along kids, or perhaps someone special, who could lounge out on the tramp surface while lazily sailing along for a sunset cruise on a warm summer evening.

All in all, I think the Back Bay SOT should be a really fun boat to own for warm water/warm weather boating adventures. It has the capacity to carry enough gear for several days out on the water. When rigged with a sailing system of your choice, it can also cover some pretty good distances if the winds are favorable. Plans for this boat and all its variations will be available from this site and Duckworks Magazine.

Chris Ostlind

Lunada Design

Blackwater 16

Thin Water Tunnel Hull design

Black Water bow low w

Recently, I put up an informative article on two, economy Jonboats; Swamper and Swamp King: Those boats were drawn to address a very simple and practical approach to a thin water, all-purpose utility skiff and there has been a very nice response from readers seeking plans.

Taking the Jonboat concept further, I got an email from a boating enthusiast asking if I had ever designed a tunnel hull boat along the lines of the Swamper. He indicated that he had seen a boat something like that which had been designed for very thin water work. The boat in question was a full 20’ in length and he felt that the size would be just too much for one guy to either pole around or man- handle in any kind of windy situation. So, he was asking if I had one like that about 16’ long.

It turned out that I did not, but weirdly enough, I had been tossing an idea around very much like his request for some time. He was kind enough to direct me to the website where I could take a look at the fine design work of Jacques Mertens and his XF20.

To be completely candid, I felt that the XF20 was quite a nice boat in every respect except that I had a customer who was asking about one for his needs, which needed to be 4 feet shorter. I had already designed a full-tilt, 18’ vee hulled flats machine for fast runs across open, choppy bays and thin water poling sessions called The Flatsmonster.


Flatsmaster18 Aft Obl w

So, I took many of the ideas I had in the Flatsmonster design and the Swamper series and combined them with the really nice elements of the XF20 to create the Blackwater 16.
Because of this choice of bottom shapes, this boat will be a lot more fun if you try to take it across a choppy body of water at speed. The forward vee shape of the hull will allow for faster speeds in open water as it will help to cut through the waves rather than bounce over them. As a swamper’s poling machine, it will excel in the narrow backwaters and thin mangrove estuaries where some really prize fish hang out, well out of reach of conventional fishing boats.


This is a pocket tunnel hulled boat with a wide stance that can support two fishermen and all their gear in very, very thin water. The hull has defined, 8 degree vee sections up front to help break some of the light chop one might find on backwater sessions in the late afternoon. The run aft from amidships is very nearly flat to allow the boat to plane easily with a very small outboard.

Black Water bow obl above w

If you want to take this boat into the Bayou and hunt for a pig, you’ll find that the hull can carry a very sizeable load with ease. I can really see this design as perfect for a duck hunter. Just rig a short mast in the center of the hull and hang a camo net over the gunnels and you have room to spare underneath for your cooler, your gun selection and the battery powered TV with earphones.

I’m not going to go into the technical description of the pocket tunnel, as there is a wonderful paragraph on the functional aspects on the Bateau site. Needless to say, the tunnel allows the engine to be raised up higher than normal giving additional clearance in the water for the prop to run in shallow water.

Black Water below w

This means you can go further into the creeks in your boat while using the engine. That translates to being able to stay out longer and come home later because of the additional speed over a poled boat in really shallow water. I figure nearly four additional inches of water depth before you’ll have to shut it down and paddle compared to a conventional Jonboat.

I suggest that you don’t exceed 30 hp for an outboard on this boat so that you can maximize the potential of the thin water capability. It’ll run surprisingly good with a 10-20-hp engine and in thin water and tight quarters, a lot of power would just go to waste, anyway. There’s a tendency to install too big an outboard on most recreational boats. I’m hoping that most folks recognize that a lighter, more efficient engine is actually better all around for 90% of all the boating work you will need to do.

Black Water structure w

Construction of the boat is in stitch and glue style with 3/8” hull bottom panels, deck, seat and fishing surfaces and ¼” plywood everywhere else save the transom. There is a lightweight framework truss in the hull beneath the deck to give the boat longitudinal strength. The suggested bench seats and forward fishing platform also serve as flotation chambers to keep the boat afloat in case it is swamped. The builders of this boat have the potential to build the interior out anyway they would like beyond the supplied bench seat design, but the more they add, the heavier the boat gets and that starts to take away the thin water capability of the design.

As shown in the illustrations, there is a midships frame and a continuous surface deck. Under the deck are two, full length stringers. These additions provide for a near bullet-proof hull with an added benefit. If the hull skin were to be holed from an unseen underwater obstacle, the flooding would be confined to the area of the damage as the compartments under the deck are sealed from one another to provide flotation integrity. Yes, the boat is a little heavier, but the payoff is in the enhanced safety, and hull rigidity if you decide to take it up to faster planing speeds.

Black Water aft obl wThis is an easy boat to build and it will provide hundreds of hours of enjoyment for the owner, especially after he customizes the interior to suit his favorite applications and fits-out the boat with all the trick goodies for his recreational passion.I suggest that the boat be built with epoxy taped seams inside at all joints with a full layer of epoxy glass on the outside of the hull. Prudent builders will add a layer (or two) of extra glass at all the sharper, hard corners to protect them from the inevitable banging a boat of this type will receive during use.

Plans will be available in the next month from Duckworks and will run USD$75. They include full-sized paper templates and detailed instructions regarding any of the stuff that is not straight forward, simple. There is also a suggested layout map for nesting the panels efficiently. The templates allow you to simply scarf together the ends of the full sheets of plywood, layout the templates, trace a line around the edges and start cutting the hull panels. No lofting required and quite a bit of time saved plotting points and bending sticks.

Chris Ostlind
Lunada Design

Swamper and Swamp King

A Superior Weapon for the Outdoorsman

Swamper King & Swamper

One day I was driving around the industrial area near my boat shop and happened to pass the local power boat center. Sitting out front of the store were two, rather homely looking aluminum skiffs that are typically used around Utah to hunt ducks and geese and perform general boating duties for outdoorsmen.

I had never really taken a good look at the type before as I had more pressing matters in front of me trying to finish the build on a sailboat. For some reason, I pulled over to just get an idea as to how these metal boats went together and to understand the shapes that went into the hull. Most folks refer to the form as a Jonboat, although I’ve also seen it as Johnsboat and Flat-Bottomed Skiff, by various other sources.

Jim Michalak’s version of this simple skiff has been a real hit with homebuilders and there’s a bunch of good reasons why that’s so. They’re easy to build, provide hours of trouble free operation with the simplest of outboards and can do just about anything you could ask for a utility boat.

I went home that night and dialed-up the design software and started fooling around with a few ideas as to how I would design one of these boats for my portfolio. The result is that I came up with two versions that are very much alike except that one is a bit longer than the other for added carrying capacity is.


Swamper 15 bow obl wThis boat is designed to take advantage of the physical properties of the standard, 4×8’ sheet of plywood and make the most of the sheet goods while still imparting a bit of style and form enhancement to the hull shape.

Rather than design a straight, flat-bottomed hull, I chose to give the Swamper a very slight Vee shape for the underwater parts. This gives a somewhat better ride through choppy conditions such as those you would find on any small lake when the wind comes up. If you’ve ever ridden in a flat bottom hull while pushing through small waves and experienced the slamming effect that comes with a flat surface as it hits the oncoming wave, you already know what I mean by this.

The overall length of the boat is 15’5” and the overall beam is just a shade over 55”. The height is 22” along the sides with the gunnel rising from that height in a soft curve, yielding a bow that is only 28.5” above the floor of the boat.

The main components come out of seven total sheets of plywood. The two bottom panels are from 3/8” material and the rest of the boat is from ¼” stock with the exception of the transom which is built from two layers of 3/8” ply. The boat is epoxy filleted and taped on the inside and completely covered in epoxy glass on the outside surfaces. The build style is simple, stitch and glue with one butt joint connection to be made to get the full-length hull panels.

There is a full-length stringer at gunnel level and it is covered with a four-inch wide cap rail completely around the boat with the exception of the transom mounting location for the engine.

Swamper 15 aft obl wBuilt-in flotation chambers are installed throughout the hull, starting with a big standing platform in the bow that is suitable for fishing. The forward seat can be enclosed with watertight bulkheads as is the far aft seat platform. Two enclosed flotation boxes sit on either side of the engine splashwell. You can swamp this boat and it will not sink.

The flotation chambers can be easily adapted to provide on-board storage if the builder installs watertight hatches or inspection ports.

I feel that the optimal, outboard engine size for this boat would be in the 15-20HP range. It will work just fine with a smaller engine, though, as the boat is quite light. I’m sure somebody will hang something bigger than this, but I’m not recommending it.

Swamper 15 above w

The Swamper is perfect for fishing; hunting work related tasks on the water and just plain old fooling around. It can go into some pretty thin water with its draft of just under 7” at 650 pounds of displacement and can easily be setup with oars and a removable center seat for human powered applications.

If you live out in the country and have a good relationship with the local Sheriff, the Swamper will fit snugly between the wheel wells of the standard American pickup. With the tailgate down, you’ll have five feet of boat hanging out, but it is doable. Again, I’m not recommending the practice; just letting you know it can be done… if you’re so inclined.

Normal transport would be with a lightweight trailer, which would allow you to keep the outboard on the boat for short distances. A 15 Hp outboard doesn’t weight too much, but I prefer to see them removed from the transom for transport over long distances.

Swamp KingSwamper-Swamp King Comparison w

This boat is very much like the Swamper with virtually the same lines. The biggest differences are the length at 18’, the ability of the boat to carry more weight and the addition of an extra, installed seat with its enclosed flotation volume. With an extra layer of ¼” plywood on the transom, this boat can easily handle a 30-40 HP motor.

The costs to build the Swamp King are slightly greater due to the added plywood for the increased length and some additional trim, structural material as well as extra epoxy and glass.

Swamper-Swamp King Comp Bow w

Even though these are simple boats, they are capable of providing years of wonderful service to the owner/builder with only very minor maintenance. If you have a teenage son or daughter who likes to enjoy outdoor activities with you, this boat would make for a terrific joint project over the winter. Either the Swamper or the Swamp King would make an excellent first boat to hand down when one of them gets old enough to have a boat of their own.


Big Horn Solo Canoe


Big Horn Bow w

Right up front, I’m going to give a full tip o’ the cap to John Winters, Canadian boat designer, for the inspiration to design this particular canoe. John’s Osprey II S&G design is a beautiful example of a designer bringing his enormous, gifted skills to the worktable. I wanted to draw a solo, tripping style canoe for 4mm marine plywood construction, so I took a long look at the Osprey to see if there was anything I could do differently with the form.

Note: At the end of this article, there is a report from a builder and the results of a committed journey with the Big Horn in the Boundary Waters Canoe Area. Please continue reading to discover a first-hand report as to how the boat behaves in the real world. From a designer’s perspective, it is incredibly satisfying to have independent verification of all the hours that go into the design of a boat like this one.

In Winters’ design, there is a very nice, tumblehome chine along the shear to give additional paddle stroke clearance. I have built boats before that used a similar tumblehome panel and it turns out that they can give the builder some interesting problems when it comes to constructing the hull.

This tumblehome chine is very slender in width, which requires the builder to have a reasonable set of skills to wire it in place prior to filleting or they will end-up with a potentially wavy hull section that just won’t go away short of doing it over. Since I was looking to draw the Bighorn for easier construction for the average guy, I decided to drop the tumblehome panel and instead raise the outer hull panel to maintain freeboard. The result is a six panel hull that is easy to build and nice looking.

Length – 15′
Width – 30″
Draft @ 280 lbs. – 3.8″
Weight (estimated) – 42 lbs. (Actual weight 38 lbs.)
Rocker-bow – 2.3″
Rocker-stern – 1.8″


Big Horn Aft wThe hull shape is asymmetric in form with the widest point (and it’s center of buoyancy) just aft of the hulls’ midpoint. The hull also has decidedly enhanced rocker fore and aft when compared to traditional canoes of this size. These two design features give the boat very solid, straight-line tracking, as well as wonderful response to turning stroke input from the paddler.

At full, 350-lb. displacement load, the Bighorn has just less than 8” of freeboard amidships. I don’t see this kind of load in this boat unless the owner is going out for a very long solo trip and needs to carry a lot of gear. More likely, you’ll be seeing an all-up, ready for trouble, load of around 290-300 pounds, depending on the weight of the paddler. I figure this boat can be built at right around 42 pounds, providing the guy with the resin doesn’t get too generous with the glue.

Big Horn Above w

The seat setup in the renderings illustrates my take on an integrated unit recognizing the typical canoeists needs when out paddling. There’s a comfortable, sculptural sitting area much like the tractor-style seats one sees on the Wenonah canoes. It is coupled with an integrated pocket on one side for camera/binocular/etc. and on the other side… a circular, net bottomed opening to hold the beverage of your choice. (Ever had a can of coke tip over in your canoe while paddling because there was nowhere secure to hold it? Makes for a fun clean-up session, doesn’t it?)

If you don’t care for the integrated seating system, you can always use the traditional, woven caned seat, a simple, stretched canvas platform or a woven-webbing seat. For that matter, you could always buy a tractor seat from Wenonah.

Outside the typical description of a solo canoe introduction, I decided to include a little extra teaser for those so inclined. I drew a set of outriggers specifically for this boat.

Big Horn with Small Amas w

They aren’t fancy in appearance, but they are very simple to build, easy to use and they provide enormous stability to the boat if you’d like to fish, shoot pictures, take a nap, shoot birds, etc. If you were so inclined, they can also be used with a modest sail rig to allow the Bighorn to be sailed like a trimaran, though don’t be expecting these amas, or the suggested sail rig size of 30 sq. ft., to provide much more than a pleasant sailing experience. Still, it could be fun on the right body of water.

Water Test Report by Stan Heeres


Build process documented along with the first trips out on the Boundary Waters Canoe Area

The complete web record of the Heres build is currently not available. I’ll search for it and locate what I can of the document.


Stan Heeres’ recent comments as follows:

“I purchased plans from you for the Big horn a few years ago. My son and I built the canoe and have since been on 2 Boundary Waters trips with it.
I promised you that I would detail the building process. I did and am just finishing the presentation up and will post it soon.
I have also built the John Winters Osprey (both the strip version and the plywood version). Here are a few details”

Strip Osprey

Lightest(34 lbs), receives the most comments by a wide margin (it looks really good), slowest of the 3 and hardest to keep in a straight line of the 3 at speed.

Plywood Osprey

2nd lightest lightest(36 lbs), very functional but does not get the comments, 2nd fastest and stays in a good straight line.

Big Horn

Heaviest(38 lbs), glides like a dream, Kevin, who uses it, will effortlessly pull away from the other canoes, tracks straight as an arrow.



It’s pretty clear that I am proud of the boat and how it has turned-out for an experienced canoe builder. Being able to say that one of my boats can effortlessly pull away from a design created by a known master in the trade is exciting. That it also has terrific tracking manners when loaded and out on serious water, really makes all the design considerations worthwhile. Stan, thanks so much for the really kind words on the boat. I’m really looking forward to Kevin’s report.

Solo 12 and 14


I have developed a new, personal trimaran for small adults and kids called the Solo12. This is a car toppable boat that is meant to sail with no facility for human power other than hauling out the spare canoe paddle and getting with it. The total displacement is 300 lbs. all-up and should tip the scales at about 130 lbs. before getting wet. So, there’s room to wiggle for a wiry dude who wants to tool around in quiet waters and have a blast in a semi-reclining position. Steering is via a pair of pedals and cables to the rudder cheek block, much like a kayak and all the sail controls are fed forward so there’s no need to hike out at all.

The sail area is 56 sq ft. The amas are generously sized to avoid getting out of the cockpit except to hang-out on the beach with friends and have some lunch. Lateral resistance will be provided by a side mounted leeboard on a swivel mount. This will give the boat plenty of upwind lift while being a safety oriented feature that kicks up and out of the way for beaching, or encountering underwater obstacles

The aka tubes are aircraft aluminum and will be segmented with the same spring pins and fitted ferrules you see on take-a-part paddles, so that the amas will reconnect right up next to the main hull for transport and storage. A very compact unit for putting on the roof of your car and going off to the beach, or lake, for some fun.

The build is 3mm marine ply with a full layer of glass outside and taped joints inside. Easy to build, easy to move around the launch site and perfect for learning to sail with little kids as they can sit between your legs and learn how things work. Later, the same kids can take the boat out on their own and there will be no fear of them tipping over unless a tornado hits the area.

There is a companion model at 14′ LOA for slightly larger sailors, all within the car-topping attitude that this boat represents. The SOLO 14 has an optional ama design that allows the removal of the leeboard as the lateral resistance will come from the underwater fin shapes of the amas. This keeps the stuff hanging in the water to a minimum while still allowing a decent performance capability. fewer moving parts will mean simpler maintenance and less stuff to possibly break while out sailing. The rendering above shows the finned amas in place.

Chris Ostlind
Lunada Design

Rocky Point Sea Kayak

Rocky Point-lunada_bay

I grew up just a couple of miles from the Palos Verdes Peninsula along the coast of Los Angeles County and would often snorkel in those waters for abalone and lobsters with a group of my friends. One of the first “boats” I ever worked on, a leaky, 12′ paddleboard rescued from the heap out behind the main Lifeguard station in Redondo Beach, was used to explore the area with my buddies. Later, we cobbled together a catamaran of our own making by screwing together two of the paddleboards down on the beach and paddling both of them out to our favorite dive and play area.Guarding the northernmost entrance to Lunada Bay is Rocky Point. The waters around Rocky Point, which is the northern limit of the famous big wave riding area known as Lunada Bay, can be anything from totally benign and calm, to a full tilt, out of control melee of oceanic surges and thundering waves. When I started to design boats, I instinctively drew upon locations from my boyhood watery exploits and the name for this sea kayak, Rocky Point, came from this familiarity.

The Rocky Point is designed as a very fast, no-nonsense expedition touring boat with the capacity to carry the necessary gear and stores for an extended stay away from civilization. Obviously, with its narrow beam, this is not a beginner’s boat. Experienced paddlers, though, will settle-in quickly to its gently lessened stability and be able to make the most of the very small frontal area and very long waterline.

The prismatic coefficient of the hull is set to .55 which will allow the paddler to reach and hold a very fast cruising speed. The boat should be equipped with an expedition class rudder to provide a gentle assist in turning as the hull has reduced rocker from my other sea kayak designs and turning was considered a skill for the advanced paddler for whom the boat was created..

Length Overall
18′ 6″
Beam Overall
Length at Waterline
18′ 5″
Beam at Waterline
300 lbs. at design waterline

Chris Ostlind
Lunada Design








Driving Sodebo w


Sports Car Performance on the Water


Over the past couple of years, I have taken a break from my boat design work. During that time, I’ve been able to reassess my connection to the craft. The last boat I designed was the Europa 20, which is a trimaran meant for vertical strip foam construction with sandwich style, infused epoxy/glass laminates inside and out. The Europa is a boat for very fast day sailing with a very light hull and a very big rig. A boat that is not for everyone, to be sure, as it requires a level of skill that the average guy does not typically cultivate in the course of experiencing their recreational boating interests.

In stepping away from the larger, more powerful beach type multihulls, I came around to the desire to produce a smaller, very quick and sensitive boat that would appeal to recreational sailors and not just those guys who want to blast around with their hair on fire (though I do suspect that in the right hands, this boat will do just that). The new design had to be easy to build with standard, marine plywood/epoxy/glass techniques that did not rely on exotic layups with spendy carbon cloth. (Well, maybe the carbon will sneak in there a bit on the beams for the guys who want to play with a bigger rig)

Looking long and hard at the smaller skiff-like hull designs I had done before, such as the Montage, I decided to draw the new boat in that same general size, but with a very different approach when it comes to how the boat achieves its performance potential. Where the Montage has a relatively spacious cockpit capable of taking on a couple of adults, (or a parent and a couple of smaller kids) the new, Corsica 15R trimaran would be for one adult (or accomplished kid) designed solely for a unique, one-up sailing experience within the small beach multihull genre.

Corsica15R bow high water wMuch like a performance dinghy, the Montage has a wide, flat sailing surface conducive to the planing of the main hull. It’s more like an outrigger supported dinghy in that regard, than it is a trimaran. Certainly, the Montage fits within a grey area when it comes to defining nomenclature. The Corsica 15R, however, would be very much like other high performance trimarans with very slender, easily driven hulls that have the potential to achieve boat speeds well beyond the typical displacement design. There is no main hull planing function going on with the Corsica 15R. It is all about pure, straightforward achievable speed via well-known multihull design thinking.

As a result, the boat has minimized clutter when it comes to excessive high-tech trickery. With that approach, the Corsica 15R is also going to be a boat that has much lower maintenance requirements in order to keep it in top sailing condition, as well as a much lower realized cost to get it on the water and ready to sail.

If you are into cars, as I am, then think in terms of a nicely pumped, Mazda Miata, type of boat that would be a cool, weekend canyon racer for one person. A boat that could blast around the local waters in a good breeze and give chase to other small, fast, multihulls being sailed by crews of two.

The result of this conceptualizing process is the Corsica 15R. The C15R is a boat of modest, marine plywood build techniques and is very light weight for its generous sail area. With this boat, the normal sailing position would be the skipper, semi-reclined within the main hull, driving his machine like an F1 Grand Prix car. In this configuration, the boat is designed to utilize foot pedals for steering, leaving the hands free to work the sheets. But, that’s not the only way to sail this boat. Owners who wish to sail in a more conventional multihull style, can sit-up out of the cockpit and onto the main hull cockpit gunnel, or even the trampoline surfaces all the way out to the ama, where they will steer with a tiller extension.

Corsica15R above w

A construction style in multichine, 4 mm marine plywood, allows the boat to be assembled in a well-understood fashion that will go together quickly. With a subtle placement of minimal stringers and sufficient bulkheads, the C15R becomes a strong main hull shell that can absorb the loads from its sizeable rig, turning the power of the sails into forward thrust in the water.

There is no fully enclosed transom on the vaka hull. The cockpit deck is slanted gently down and aft for automatic self-draining, such as is seen in sport dinghies and larger race boats. A collection of bulkheads under the cockpit deck provide structural support and watertight compartments ensuring that the boat will not likely sink even if large sections of the bottom are torn out from an underwater hazard while smoking along in a gin clear lagoon.

The demounted boat can be assembled easily by one person. The gently gull-winged akas are built with a glassed box beam core.  The inboard ends of the akas slide into tapered sockets in the main hull and are levered in place with stainless waterstays to make ready for sailing. This, tapered socket technique prevents binding while assembling the boat, while providing a solid, hassle-free and weight minimized demounting system. The leading edges of the akas are smoothly shaped foam blocks that are glassed onto the box beam to provide an aero component, as well as creating reduced drag from waves and spray. The akas are hard fastened to the amas as a complete assembly that is easily removable from the vaka hull. The trampolines stay mounted to the akas and amas for transport and only have to be hooked and tensioned to the main hull during assembly.

The mast is a stick from a Hobie 16. I specify the addition of a set of spreaders from the Hobie 18 mast to stiffen up the H16 mast to handle the additional righting moment generated by the Corsica design. Naturally, I’d prefer to see fresh sails in something like fully battened, Pentex laminate, but builders on a tight budget could also work with a loft service to tweak a reasonably fresh Hobie 16 main and jib and do just fine. The addition of reefing points on the main are strongly suggested, as well as the use of furlers for the jib and spinnaker/screacher. For those who desire fresh sails for this boat, I would recommend the folks at Whirlwind sails in San Diego, California.

Corsica15R bow water w

A removable carbon prodder sets the tone at the front end of the boat. The stick originates as a carbon windsurf mast, so it is easily found on the used market and equally replaceable, should it get poked into an unyielding environment. For trailering, the sprit unpins, slides out of its socket and is stowed in the cockpit for transport and storage.

Corsica 15R Specifcations

LOA                                         14’ 11”  (4.54 m)

BOA                                         13’  (3.96 m)

Displacement                         650 lbs.  (294.8 kg.)

Sail Area (upwind)                 218 sq. ft.  (16.17 sq. m)


Spin                                       142 sq. ft.  (13.19 sq. m)

Mast Length                           26’  (7.62 m)

Draft (board up)                     1’  (.3 m)

Draft (board down)                42” (1.07 m)

The mast is raised by the traditional beach cat method of physically lifting the mast with the base pinned to the mast step, or by utilizing the long daggerboard in its trunk as a form of a gin pole. A forward hoisting line is led over a pair of sheaves at the top of the daggerboard and down to the hand cranked winch on the trailer. Mechanical leverage quickly raises the mast so that the forestay can be fastened to the bow, stepping the mast securely. You can see a few photos of the process at Brent’s L7 trimaran site:  This is a very simple way to raise a mast should you need to avoid the trad lifting exercise for one reason or another.

I chose to not go with tricked-out, curved lifting foils in the amas due to construction complexity and added cost for the builder. Foils of this type are hard to build correctly by hand, as are the needed curved trunks in which they slide. Instead, the boat is equipped with a daggerboard that is inserted through the deck of the main hull in front of the mast which angles aft to exit the hull below the waterline. A daggerboard and trunk of this type are much simpler forms to build and orient in the hull. It is also just one main foil, where lifting foils need to be made in pairs, one for each ama. Lifting foils also need complex control mechanisms to retract and deploy the foils and they have to work from the cockpit remotely with the foils mounted way out in the amas. The needed controls are an interesting problem when the boat is 13’ in width and the driver is semi-reclined in the main hull.

Note: I’m not against an owner who might want to experiment with foiling for this boat, even if it is just foil assist and not full flying. It would require a lifting t-foil style rudder and twin Bruce style foils in the amas, or, if a person is really accomplished as a composites builder, they could make a pair of matching c-foils for the ama. The owner just needs to know what level of additional work is involved and at what skill level they need to perform in order to get the desired result.

Corsica15R beam water w

If you are on a budget, the rudder and headstock from a Hobie 16 will work just fine for the Corsica with some mods to the tiller. The more deluxe, Rudder 25 system from Dotan will also work well, should you have the coin.  If you plan on pushing the boat hard, then a longer blade will be required, or you can get yourself invested in the process of putting a rudder on each ama and have stunning control at your finger tips. On the down side, that change will cost you a bit out of your pocket and at the launch ramp in setup time… though I can see a nifty rig with light alu tubing and the use of snap buttons as a cool solution.

The Corsica 15R will be a light boat built from familiar materials. It should be a fairly simple building experience for the owner and will fit comfortably into any typical garage space, making it easy to find a building location. It will quickly assemble for sailing and be hassle free with minimal maintenance required to keep it in top form. It can be towed behind any compact car on a typical beach cat trailer and when demounted for travel, is road legal anywhere in the world. On the water, this boat should be quite quick and behave with predictable, pin-point sailing manners. With the skipper slung comfortably in his reclined cockpit seat, he will be decently protected from the effects of the weather and sea state while tearing around his local waters.

Chris Ostlind

Lunada Design


Dual Mirage Drive powered, two person launch

Duckworks - Strider

Some time back, I encountered an ex-pat American, now living in Melbourne, Australia, by the name of Mack Horton. Mack wanted to build a two-person boat for cruising the harbor and waterways of his hometown, Melbourne. He was looking to propel his boat with a twin setup of the wonderfully innovative Hobie Mirage drive designed by Greg Ketterman. I really liked that idea as I had already done a few different boats that were Mirage capable, but they were all solo boats. This design concept opened a new door for me, as it would allow me work out the balance and weight issues for a twin drive and once built, I could also discover how much more speed potential might be available beyond a solo drive.

I had a hull in mind from my portfolio that would need to be “massaged” just a bit to get the form stability and low-speed performance for which I was looking. The boat had to be able to handle potentially large boat wakes and small chop of the open regions of the harbor and still be easily driven by human leg power.
Duckworks - Strider
I was looking to achieve some of the lines of a classic launch with reasonably low windage and yet, enough freeboard to ward off the possible conditions. Surprisingly, the hull form came directly from a previous boat shown  at the Duckworks Magazine, the A18, canoe/trimaran.
The A18 hull had a very strong bias towards higher speed potential with only a nod to being driven at slower speeds, so a slimming process had to take place in the forward and aft sections of the hull. Likewise, the beam of the hull was pulled out some to give the boat a solid degree of form stability so it could ride the wakes of passing freighters in the harbor when taken abeam.
I sent the plans off to Mack and he promptly got to work on the boat at his favorite spot for boatbuilding, the Melbourne Wooden Boat Center

Cut to the Chase

Mack has now finished the boat and has had it out on many outings. He’s learning a lot about boat trim and optimal placement of the heavier pedaler for best performance and handling. Besides the still photos showing the boat on the water, Mack has also provided a pair of video clips showing the boat underway.




Clearly, Mack’s Strider, Ripple, is showing itself to be a pretty fast boat when being propelled by two average people. This is being done from a semi-reclining position with hands free, while enjoying the sights in the Melbourne harbor and adjacent waterways. Here is a link to an article I wrote for Duckworks Magazine that shows the GPS track and speed data achieved by the Strider design:  This is pretty heady stuff for a human-powered vessel intended for casual cruising and not blistering speed.

Mack reports that one of the ubiquitous dinner cruise boats, that you see in just about every harbor of the world these days, pulled alongside and challenged both he and his friend, Justine, to a little race. Off they went with Ripple easily leaving the cruise boat in the dust. Let’s overlook the fact that powered cruise vessels of this type have strict wake generating spped limitations…
Later, as shown in the video clip, Mack and Justine took-on a fully crewed Dragon boat. Dragon boats measure 40 feet in length, 4 feet in width and carry 20 paddlers, 1 drummer, and 1 steers person. On average, these boats weigh 500 pounds. Understandably, Ripple could not quite match the speed of the Dragon boat with twice the waterline length and 20 paddlers. Perhaps there could be a triple version of the Strider in the future? One that is longer, more slender and much, much faster.
Duckworks - StriderThe Strider design calls for a very straight forward stitch and glue build method in 4mm marine plywood with glass/epoxy laminates inside and out. The twin Mirage trunks sit cleanly in the hull allowing for a comfortable seating arrangement for two persons and their day pedaling “stuff” such as binoculars, cameras, food, drink, blankets, etc.
In the right environment, the boat could easily be used for overnight camping as well, as there is plenty of displacement capacity for more gear, should the owners wish to use their boat in that fashion.
I expect to see these boats being equipped with Bimini covers and small forward dodgers. The interior hull sides will probably be lined with neat rows of mesh bags to storage of the small things that make for a really nice time on the water, such as: sunscreen, lip balm, mosquito repellant, drinking water, snacks, camera, VHF radio, GPS, etc.
Maybe you have a cabin/cottage on a lake where the general store is across the water, but a short distance, but to walk, it would take an hour to get there. Strider is an excellent, human powered boat for a trip like that. An enterprising person could equip her with an all-weather set of side panels to mount under the Bimini edges, allowing trips to the market in any conditions, short of a full-on gale. (Check out the last video clip above)
The boat is cartoppable, much like a large canoe would be, but I’d advise the person doing the loading be reasonably fit and/or have a really sweet loading system, or technique, as the boat does weigh right around 70 pounds without the Mirage drives in place.
Mack has kindly supplied some very interesting speed marks for the boat that were confirmed with a Garmin Edge 305 GPS with wireless heart rate and cadence monitors.
Highest speed attained with two pedalers…… 7.2 knots
Highest speed with one pedaler………………… 5.7 knots
Average speed for one hour w/ two………….. 4.8 knots
Average speed for two hours w/ one…………. 3.9 knots
Turning circle for the Strider is 33’

These figures run pretty much spot on with my estimations. They also indicate that the hull has gotten to its, “not gonna go there” speed limit and will be pushing uphill on its bow wave from that point on.

Duckworks - Strider

While underway in Strider #1, “Ripple”, it is not unusual to be hailed from dockside and beasked, “What is it?”, “How does it work?”, “How much does it cost?”, and his favorite… “It looks like it has an engine!”

Response has been very positive from athletes, because it’s fast… and from non-water type folks because Strider is stable, comfortable, dry and “not scary”.

One of the reasons that Strider is so stable is due to the recreationally respectful beam of the hull. I’m working on a much faster version of the Strider design concept, which should pretty much take the Mirage drive out to its theoretical top speed limit.

All in all, Strider is a really fun and stable human powered vessel designed for recreational pursuits by two people. It has the classic look and feel of a traditional launch to it while underway and can easily power-up to get out of the way of oncoming traffic in a crowded harbor, or lake setting.

Chris Ostlind

Lunada Design


Making use of Mirage Drive propulsion with more efficient hulls designs


Nagare 21 Bow Obl w

Nagare  (nah-ga-ray) is a Japanese word meaning Flow.

The two boats in this group are 17 and 21 feet in length and are known simply as the Nagare 17 and the Nagare 21. Both designs make use of the popular Hobie Mirage drive for principal propulsion with the 21 footer Nagare 17 bow obl wbeing a double Mirage setup and the 17relying on a single Mirage.

Both of them are configured as trimarans with fairly small and unobtrusive amas designed to give the boats remarkable stability in a wide range of conditions while allowing the vaka, (main) hull to be decidely slender for more effective drive through the water.

The Nagare sisters also have incredibly narrow waterline beam numbers that, when coupled with their fairly long hulls provide for very easily driven hull forms for high efficiency per unit of energy applied.

I expect both boats to operate at the very high end of commercially available paddled boats of the same length, beam and weight. So, yes, they can go pretty quickly, but that’s not the real purpose.

The real benefit of the design genre is through the ease with which they are propelled at any given speed, compared to other boats of their size. This efficiency translates directly to those using the boats as less tiring for miles covered, or greater speed with the same effort as other, wider designs.

Because the propulsion is derived from the largest muscles in your body, the leg muscles, rather than the arms and shoulders, there will be less fatigue for each mile traveled. Because leg muscles are so much bigger than arms, they will be able to do more work in a given period of time, making for longer possible trips, as well as the mentioned lower fatigue issue. With a less fatiguing effort, more people will be able to enjoy the experience of being out on the water for daylong adventures.


Nagare 21 Aft Obl w

The Nagare 21 uses a set of amas, mounted on a pair of simple, anodized aluminum tubes with quick release snap buttons holding the sections together for easy disassembly for car-topping. If a trailer is used to transport the boat, the beam of the Nagare 21 falls well below trailer maximums, so nothing special needs to be done to take the boat to and from the water. Two Nagare 21’s can be trailered, or car-topped, by removing one of the amas and placing the main hulls close to one another on the racks, or trailer. The removed amas easily fit inside the hulls and they are ready to go. The whole affair on the rooftop is very much like a pair of sea kayak doubles. Because of the length, I would not mount a boat this big on any compact cars. You would be very likely to rip the rack right off the roof in strong side winds.

Steering is by means of a simple, flip-up style kayak rudder with control lines run through the hull to a convenient steering lever in the cockpit. I suggest the SeaLine SmartTrak rudder system (do a search for supplier), the P-41 Multi-purpose rudder from Onno Paddles the Feathercraft rudder system for hardshell boats.  These are really great rudder units and will give excellent steering control with minimum drag.


This boat can be built with a full cockpit tub so that it functions as a Sit-On-Top kayak with full drainage through the Mirage drive openings. Auxiliary drain ports are located in the tub for rapid removal of any water that comes in over the side of the hull. I suggest the SOT option for warm water users, with the more traditional kayak style, Sit-Inside hull form for those who will be using the boat in colder water, or more frequent inclement weather.

The SOT version has internal bulkheads for support of the SOT tub, along with the capability of adding a small circular deck plate for an additional watertight compartment in the cockpit that is perfect for small items, such as cameras, wallets, car keys, etc.

The SOT variation is an optional element to the base plans. If you wish to built it as an SOT, drop me an email at my regular email address and I’ll get back to you.


This is not really a boat that is meant to go out in rougher conditions, such as those where a full-blown sea kayak might be right at home. It’s meant for quieter waters, such as lakes, bays, harbors and bigger rivers. It can take a session in 1 or 2 foot breaking surf, but I would not expose the boat to bigger waves, especially in a shore break scenario. You may find yourself out from the shore a bit when the wind comes up, producing steep, choppy waves. The basic Nagare 21 will handle this easily because only the cockpit will be exposed to swamping. The amas will keep the boat stable while you pedal to shore, or a quieter place on the water, where you can bail-out the boat and continue.

It is a perfect boat for sightseeing, bird watching, fishing, photography, and just simple, energy efficient cruising with near bomb-proof stability (you can stand up in the boat while out on the water without your partner coming completely unglued, for instance).

The Nagare 21 is a fast, comfortable and unique boat for a couple who like to get out on the water, but do not want to hassle with the business of capsize that is present in other types of boats, such as kayaks and even canoes.


The solo version of the Nagare series has some very different twists, compared to its bigger sister. It has the same, highly efficient and easily driven, slender hull technology, the same set of trimaran style amas well aft for big time stability, the same generous cockpit opening and the same convenient utility for car-topping or lightweight trailering.

The design elements that set this particular boat apart from its sister craft is that the Nagare 17 has a very special capability when it comes to fishing.


Anybody who builds the Nagare 17 and intends to use it for fishing will probably be knocked-out by the potential for facing aft while trolling. Imagine using your legs to quietly drive the boat forward while you casually set trolling rigs, eat a sandwich and keep an eye on the fish finder… all while keeping an eye on the rigs you have set, with them easily at hand?

Nagare 17 bow obl trolling mode w

This is the signature utility development with the Nagare 17, designed specifically, for fishermen. It works like this…

The fisherman loads his boat, drops into the forward facing seat, hits the iPod for his favorite tunes and jams out across the lake at a remarkable speed for a human powered boat. He zips across the lake in virtual silence because he’s driving a very skinny and efficient hull with no engine sounds. Once he arrives, he’s going to make a few sneaky trolling passes with his Mirage drive pushing him along over that monster crew of Pike that are hanging around on their favorite piece of structure. Wham! Fish On! and the day starts with smile on his face.

If you’ve ever fished from a typical Sit-On-Top, you know that you have to face forward while trying to look over your shoulder while trolling. Hook-up and then you have to swivel around, grab the rod and go after the fish. All the time you are doing this, you have to balance the boat carefully, because the whole tamale could go over and end your day right then and there.

Well, that’s how you used to do it, anyway.

With the Nagare 17, you can take it to a whole new level of fishing pleasure. The Nagare 17 is equipped with twin Mirage drive trunks. When driving the boat forward and facing forward, the Mirage drive is dropped into the forward trunk and a tractor-style seat is dropped into the aft trunk with the seat bottom resting on the top of the trunk.

To convert the boat to aft facing trolling and fishing, you simply stand up in the boat and swap the Mirage drive for the aft mounted seat plug and the seat then goes to the front trunk… facing aft. With the Mirage drive still set to drive the boat forward, you simply sit down and start pedaling, slowly, up to your desired trolling speed.

Now, you can watch your fish finder, GPS and your trolling rigs while you continue to tool along at your favorite speed for nabbing the fish. Get one on and simply work that rod while continuing to face aft. No twisting around in your seat, no ”just about dumped it” scenarios, just simple, fun fishing in a very stable boat. What could be cooler than that?

With the fore/aft balance point of the boat set right between the two drive trunks, there is but a very minimal change to boat pitch when you change the direction you face.

The Nagare 17 is further designed to accept an insulated and watertight tank between the two aka tubes where they run through the aft deck. You can use this for all kinds of stuff like: your catch, fresh bait storage, cold beverages if you catch and release… whatever suits your needs. There is plenty of room between the two drive trunks for a pretty good sized tackle box and lots of room up forward of the trunks for any of that “other stuff” that fishermen seem to sneak aboard their boats.

Nagare 17 aft low obl w

A moveable electronics unit can be fastened at the forward end of the cockpit, or unhooked and moved around aft if you’d rather have it facing that way.

Maybe you want to cast lures or flies instead of troll. The boat is so stable with the two, wide set amas, that you can stand up and cast all day without ever feeling like you are getting the least bit tippy. All in all, the Nagare 17 is quite a boat for fishing, as well as just plain fun, recreational pursuits.

The Nagare sisters represent a unique design family for human powered vessels. They are quick, stable and with their unique styling, represent a distinct departure from the looks of traditional boats one typically sees on any given shore or launch ramp. Both boats are designed to be built in marine ply Stitch and Glue methods for the hull sections, with cedar stripped decks to take advantage of the really beautiful, smooth curves capable from that style of building. You can paint the lower sections of the hull and leave the cedar decks natural with a deep varnished finshed, for a real knock-out boat that will really gather a crowd.If you really want to have a plywood deck build instead of the cedar strip build, write and twist my arm gently. I can design that change for those who really like to build that way

Plans are not yet complete, so if you would like to build one of these two boats, please send me an email and I’ll put your name on the mailing list for information, or watch the plans section of Duckworks for the notice.


Largo… An SUV for the Water

Fuel Efficient Power Boating For a New Economy

Largo Sunroof Beam 5x7I’ve been getting a significant number of inquiries for the power version of my Gato Especial sailing cat. I let it slip out, some time back, that there would be an engine driven version coming along, but time got away from me and so, the project sat idling on the design table.

I’m kind of drawn to cars and boats that can solve a host of utility needs, as well as provide a comfortable, transportation experience. I’m about to sell my venerable Toyota Landcruiser and get myself into something that makes a lot more sense when it comes to utility and fuel efficiency. As a result, I began to think of a motorized version of the Gato platform as a Crossover/SUV type of vehicle with a big interior volume aft of the helm station and truly fuel-efficient engines to complete the picture.

The new boat would have a stand-up position for the driver with a sliding, deck-mounted seat that would allow the skipper to sit while steering. There would be a huge deck surface behind the helm for all sorts of seating and/or gear carrying options. The new boat would have a tailgate/liftgate setup for ease of loading. The new design would have a big storage space forward of the helm for the odds and ends that always end-up on a boat. Power for the initial design would be from a pair of four stroke outboard engines for redundancy, as well as beneficial weight distribution.

Largo HT Gates Open aft obl 5x7

On a personal level, I am attracted to design concepts that deliver a responsible set of solutions for this new economic reality in which we all live. I like the term, Crossover, which is openly lifted from the automotive industry, as it touches on the realities we will all face in the coming years. We are headed to a time in which our vehicles will need to do more than just give us a sedan in which to cruise around, or a truck to do our dirty jobs.

In the world of cars, the Crossover approach has created vehicles that live in the niche right between the heavier, clunkier, SUV’s and the typical, everyday passenger car. Similarly, with this new design, I was looking to take the slot right between the generously proportioned sport cruisers you see at marinas all over the world and something like a cleanly drawn work boat. I wanted some of the people driven touches of scale and fit/finish, while being able to morph from one working task to another as a truly useful, all-around watercraft.

The result would be my take on what a boat should look like which is much more fuel-efficient and less expensive to build and transport. It would provide a very high degree of utility and, of course, it would need to be wrapped in an aesthetically pleasing package.

Largo HT above 5x7

The aesthetic, design component is pretty much a subjective thing, but the fuel-efficient aspects are a design process that combines easily driven lightweight hulls, drive systems with high economy for delivered horsepower and a significantly reduced aero drag signature allowing the boat to just slip through the air.

I’m of the opinion that I have reached all the basic design criteria with this new design, The Largo.

Yeah, sure there’s a distinct connection to the Bond films, Thunderball and Never Say Never Again, with the bad guys both being named Largo. Beyond that, Largo is also a direct take on the ’48 Film Noir thriller with Bogey, Bacall and Edward G. Robinson. It is also, the well-known island in the Florida Keys where boating adventures await in every direction and one of my favorite adventure boating events, The Watertribe Everglades Challenge maintains its finish line.

Largo Specifications

LOA 21′
BOA (trailer legal) 8′ 6″
Height 6′ 5″
Displacement 2000 lbs.

Suggested engine package is Twin 9.9 hp four stroke outboards. It may not seem like it from the renderings, but plenty of interior volume has been worked into the design to allow full movement of the engines from side to side

The aft cabin space of the trimmed-down version will have the potential for a huge, manual, slide-back sunroof for a full open-air effect in the main cabin volume, as well as large side openings for breeze and visibility. The side openings can be fitted with removable, semi-structural soft windows for better streamlining and also for inclement weather.

Largo Conv aft 5x7Way back at the aft end, the boat has a floor level, drop-down tailgate, as well as a glassed, liftgate. I see this as a utility benefit when the boat is beached, bow out, in a marina slip. The tailgate will allow easy loading of gear and anything else that might be shoved in the back of this boat while it is still on the trailer. It will also give a chance to sit on the tailgate and hang out. The entire hardtop can also be removed for a full-on waterborne convertible. Or, if you like, a pick-up truck for the waterfront that can haul a whole bunch of oddly shaped objects, should you have a need for that kind of utility with friends while enjoying a sandwich or cold beverage.

The suggested engine package is based on need. If the owner wants to cruise with high efficiency and still be able to bang out 11-12 knots when he likes, then a pair of Yamaha Hi-Thrust 9.9 hp engines will do the trick. The engine setup can be equipped with remote starting, steering and power engine tilt. They both have pretty healthy alternators to keep any onboard electrics going, so lighting, navigation and radio systems can be easily powered-up.

Largo HT bow obl 5x7

Cutting edge enthusiasts will ditch the outboards and equip the boat with a bank of batteries under the deck in each hull and a pair of powerful electric motors that drive a set of matched, counter-rotating props. As an alternative to the twin outboards, this boat, so equipped, will silently cruise with a pretty decent range and be able to go to full power instantly whenever the owner wants the buzz of the electric drive potential.

The hulls of the Largo are exactly the same as those of the Gato Especial sailing cat. They are 10-1 in Length to Beam ratio at the waterline and will be very easily driven while still providing a respectable displacement payload. The is a spray chine on the inside and outside of each hull to direct wave action away from the boat while underway, as well as reduce drag on the hull. At cruising speed, a small amount of hull lift is also a side benefit of the spray chines.

The aft end of the hull bottoms is relieved with a slot to allow engine placement forward of the typical transom mounting and to allow the power tilt capability to raise the props well clear of the hull bottom for beaching and trailer loading/unloading. Moving the engines forward adjusts the balance point of the boat forward and helps with handling and pitching moments. It also puts the engines inside of sound deadening boxes, so the overall noise level is reduced while underway. Cruise the harbor on a warm summer evening with soft music playing on the surround sound system and you can really hear the soft music.

Bridgedeck clearance between the hulls is a generous 17″, so wave slap under the main deck will be kept to a minimum. This raises the overall comfort level of the boat, which is especially nice on a longer trip.

Largo Conv. loaded aft 5x7The large deck space inside the boat will make for a spacious camping environment, gear hauling space, or just about anything else you can think of doing with a boat that is this versatile. The tailgate opens to a generous 49″ width, allowing the owner to load full sheets of plywood right through the back of the boat without leaning them up on edge.

The hull volumes below the main deck can also be used for the storage of fuel, batteries, water tanks, anchor, rode, etc. It’s always a good thing to keep the heaviest items on a boat as low as possible to enhance stability and improve ride. The space in front of the main forward bulkhead can be accessed via a large hatch. This is an excellent location for lighter weight storage needs such a sleeping bags, tents, clothing, etc.

A good friend asked if the boat could be equipped with a drop-down front ramp and a walk through windscreen so that the Largo could be driven right up onto the beach to unload through the bow. The answer is Yes… certainly can accommodate that feature with a few changes to the forward structure.

Clearly, the Largo is a boat with a generous latitude of use potential, it draws design cues from a pretty diverse group of sources and sets a new standard for home built power boats with a decided edge towards fuel economy and responsible boating.

Chris Ostlind
Lunada Design