DIY Kayak Design

Berny Marsden’s Stitch and Glue W Kayak – United Kingdom

This is the latest DIY W kayak project -

It’s the first DIY design allowing to take the boat apart.

Read Berny’s account on the comments section: http://micronautical.com/diy-kayak-design/#comment-90

NEW: View Berny’s first test movie of his motorized W kayk ‘Banana Split’ -



More info here >

John Forney’s Wooden W Kayak – Texas

John is an prolific small-boat designer and builder from Texas, who’s built fifteen boats in recent years, including designs in wood, composites and skin-on-frame.
John says: -”My interest in boat building had waned somewhat, primarily because I couldn’t crack the nut of fishing comfortably from a small paddle craft. The W concept has completely reinvigorated my interest in boat building.”
John first W boat is 12 feet long and 30 inches wide, and it weighs 74 lbs. It can take two large size fishermen with all their fishing and camping gear.
-”Standing up in this boat is as natural as breathing.  One just doesn’t get the sense that anything will go wrong.” he says.
John’s next project is a ten footer skin-on-frame W kayak.

Email John Forney

jf_standing_in_blue_12ft_wooden_w_kayak_01

John standing in the wooden twin hull fishing kayak he created

“I’m on the Brazos River with my wife this day. I painted the boat Navy Blue Marine Polyurethane paint on the outside, with white Marine paint on the inside.”

Wooden twin hull fishing kayak / unfinished
Wooden twin hull fishing kayak / unfinished
Wooden twin hull fishing kayak / unfinished

16 ft Long Fiberglass W Kayak

This is a 16 ft long W kayak project realized in Europe:

16 ft long W kayak - Europe

16 ft long W kayak project – Europe

The design of this fine looking W kayak was based on a concept published on this website back in 2006:

exp_style_w_kayak
Concept W Sea Kayak – 2006

 

More technical info on speed, stability, propulsion ergonomics and other design issues related to fishing kayaks >

14 thoughts on “DIY Kayak Design

  1. Berny Marsden says:

    Hi John Forney

    I am researching methods of building a twin hulled Kayak and I saw the photo of your 12 footer on http://micronautical.com/diy-kayak-design/

    I was very impressed with your design.

    I noted that you are a fisherman and built your kayak for a more stable platform than conventional kayaks.

    My interest is in Scuba diving. I live in the northern part of England and the coast is only a two hour drive from me. However, most of the diving around the coast requires a boat and this can be quite expensive so I have been looking for an alternative.

    A twin hulled kayak seems to be just the answer. It seems to offer an easily portable boat that is stable, seaworthy, can carry dive gear and can be boarded from the water. From what I have read, they are also fairly fast in the water and can cope with tidal currents and fairly rough seas.

    I note that your 12 footer can carry two men and a load of fishing gear so I think it should be able to cope with me and my dive gear (about 230 lbs).

    If you don’t mind, I have a few questions about construction as I intend to design mine from scratch:

    1. What thickness of plywood did you use for the hull skin. Would 6mm (1/4 inch) ply be thick enough?
    2. Are the bulkheads and seat plank made of thicker plywood (3/8 or 1/2 inch)?
    3. Are the two hulls parallel or are they wider at the bow than at the stern?
    4. Did you use stitch and glue for the construction?
    5. Did you fill the bow and stern compartments with expending foam for emergency buoyancy?

    I hope you don’t mind me asking all this and if you can give me any tips on construction, it would be greatly appreciated.

    Kind regards

    Berny Marsden

  2. Berny,

    John is a bit slow to respond, so I’ll provide you with some information -

    1. What thickness of plywood did you use for the hull skin. Would 6mm (1/4 inch) ply be thick enough?
    -Yes.
    2. Are the bulkheads and seat plank made of thicker plywood (3/8 or 1/2 inch)?
    -No need for that. Howver, your biggest challenge is to prevent the hulls from splaying. You can achieve that by introducing gussets (structural reinforcement ribs) under the top of the saddle, as it was done in the commercial W500 kayak.
    3. Are the two hulls parallel or are they wider at the bow than at the stern?
    -John’s hulls are symmetrical bow and stern, as is the commercial W500 model. Note: for more efficiency, each hull should be asymmetrical, with the side that’s facing the other hull straight and flat, and the side facing outward curved. This optimizes the inflow between the hulls, and minimizes turbulence there.
    4. Did you use stitch and glue for the construction?
    -That’s for John to answer
    5. Did you fill the bow and stern compartments with expending foam for emergency buoyancy?
    -Not necessarily a good idea, since this internal space has value for dry storage. You’d better attach detachable polyethylene foam flotation (pool noodles) below the saddle, and on the kayak’s sides.

  3. Berny Marsden says:

    Thanks for this. Very helpful. I have never designed a boat before let alone built one but the w Kayak concept looks ideal for my purposes. I intend to use it for off shore scuba diving. It will save a great deal of money in chartering boats whilst allowing me access to some dive sites that I can’t reach from the shore. I’ve nearly finished designing a 12 footer that should carry two divers and cylinders. I have incorporated most of what you say in my design but I reckon I can save some weight and retain rigidity by incorporating the under saddle gussets. I’ll post some photos and videos as I progress.

  4. Berny,

    2 divers + 2 sets of diving gear is about 500 lbs, isn’t it?
    Not sure your 12 ft design would be optimal for this load, especially in the ocean.
    You may want to make your W slightly bigger.

  5. John Forney says:

    Berny,
    I’m glad to see you pursuing a home-built W kayak design. Yoav has a great design available commercially, but a homebuilder can pursue interesting inroads to the design on his own.
    I used 1/4″ plywood, sheathed in 6 oz. fiberglass for the hull. I used some strips of pine lumber for reinforcement. Two strips, 1 1/2″ wide by 3/4″ thick, went across the boat above the bulkheads at the ends of the saddles. I also put two gunwales outside the plywood, running the lengths of the boat. Underneath, I fastened two supports that looked a little like a crescent, to stabilize the two hulls. I’ll upload pics to Yoav for further description of this.
    The hulls were parallel to each other, but they were asymmetrical when viewed from the ends of the boat. The outside of each hull was more curved than the inside. If you’ve ever seen a proa, you can see the parallel. After conversation with Yoav, he persuaded me to make the insides more parallel and vertical. That was a good choice.
    I used the stitch and glue method. I’ve built several CLC kayaks and pirogues, so this method was comfortable for me.
    I didn’t use any expanding foam, and didn’t see the need, with enclosed bulkheads.
    Here’s what I would do differently:
    1) I’d focus on weight reduction. 74 lbs. is too heavy for a 12 foot boat, especially a stitch and glue boat! Okume plywood, cedar lumber, less fiberglass, lighter (4 oz.) fiberglass, no bulkheads, etc.
    2) I’d make the saddle 6 feet, not 8. We tried to make a 2-person boat. It was plenty beamy, but too short. Have you ever seen an 8-foot two person canoe? You get the picture.
    3) I’d taper the hulls more. The boat created quite a wake at hull speeed. This slowed down the top speed for a 4-mile trip I did on flat water. I did outfish everyone else, though! :)
    4) You don’t need four bulkheads. I’d make one or two at the most. Dry bags and an open space is better and lighter, I think.
    5) I’d really like to explore this design in skin-on-frame. Think of something like a long, stable coracle that you could carry easily.
    The design is really unique in the fishing world. I am very interested in seeing how people compensate for increased wetted surface area and weight to make it faster. Good luck, and post pics! John Forney fornman@gmail.com

  6. Hi John,
    Increased wetted area is largely compensated by the dramatic reduction in beam width, I.E. Residual Resistance (Rr), which becomes the dominant factor as speed goes up.
    See kayak speed >>
    Catamarans are heavier than comparable mono hulls, but this factor is overrated in such tiny boats, where the passengers’ weight is several times the boat’s weight.
    For example: A kayak weighing 70 lbs and carrying a 200 lbs passenger (total 270 lbs) weighs just 2.7% more than a kayak weighing 63 lbs carrying the same passenger (total 260 lbs).

  7. Berny Emm says:

    Thanks John. I’m just revising my design. Hulls will now be 10 inch wide by 16 inch high and the seat 10 inches wide positioned on the top between the hulls.

  8. Berny,
    The W500 saddle is 12.5″ wide at its bottom, and it tapers in its upper part, for more comfort in sitting / standing. The very top of the W500 saddle is less than 10″ wide, and the edges are rounded, which is easy to achieve in plastic, and probably harder in wood :)

  9. Here are more pictures that John sent me for uploading:

    view of wooden catamaran fishing kayak

    close up view of wooden catamaran fishing kayak

    Under view of wooden catamaran fishing kayak

    Says John: -”…I can’t stand the traditional recreational kayak, and I don’t think other folks like them much, either, after they spend some time trying to fish out of one.
    Attached are some pictures from the wooden W boat project. I’m not going to work on another one in the forseeable future; I’m working on developing my skin on frame skills.
    I’ll be checking back periodically to see how things are going…
    John Forney”

  10. Berny Emm says:

    Excellent photos John. I like the external gunwales.

  11. Berny Marsden says:

    I have been busy building my W kayak.

    I tested it today and did a dive off it with great success.

    I decided to use the aluminum connecting poles and make the craft in three parts. This has the benefits of easier construction, easier transport and easier storage.
    As I anticipated, it is very stable and should make an ideal sea diving platform. The seat section provides inherent buoyancy if it should capsize. However, I tried very hard to capsize it today and it never looked like getting close to it.
    I am so pleased with it and very glad I saw John Forney’s Design.
    I would be grateful if you could thank him for his help and advice.
    Also, thanks for your help and encouragement.

    Cheers

    Berny Marsden

    I will be fitting a small outboard in a few weeks.

    DIY-twin-hull-kayak-for-fishing-and-diving-UK

    DIY-twin-hull-kayak-for-fishing-and-diving-UK-stand-up

    DIY-twin-hull-kayak-for-fishing-and-diving-UK-stand-up

  12. fishingkayakdesign says:

    Thanks Berny,
    Looks great!
    I like the idea of being able to take it apart. It’s useful for storage and transportation.
    With two passengers plus gear on board, these aluminum tubes you’re using to attach the 3 pieces together might bend.

  13. Berny Marsden says:

    I’m fairly confident the tubing is stiff enough as it’s 3mm walled 1 inch tube and it shows no sign of flexing. I’m not sure if it will take two divers but further testing will show its full potential. I should have some video of its first test soon.

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