Instructables
Picture of Stitch and Glue Boat Construction
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The "Stitch and Glue" method of boat construction is one of the most popular methods of plywood boat construction today. It allows for easy test fits, fast assembly, and simple fixes. I recently modified the Mini-Cup Sailboat plans, normally calling for assembly with wooden stringers, to stitch and glue.

I apologize for the lack of some crucial photos, as once the process is started and the gloves are on, the epoxy usually gets everywhere so I try to limit my camera's exposure to it.
 
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Step 1: Tools and Materials

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Tools:



  • Epoxy brush

  • Sharp scissors

  • Saw

  • Drill

  • Drillbits

  • Latex gloves

  • Plastic scraper



Materials:



  • Epoxy resin (marine-grade)

  • Zip/cable/wire-ties

  • Fiberglass tape (11.1 Oz best for structural, bi-directional not necessary)



Most of these materials can be purchased at a marine supply store.





Step 2: Cut it out

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First you need to have your parts to be stitched and glued cut out. For my boat's 1/4 inch plywood hull, I used a Jigsaw to cut out the pieces I had lofted from the plans.



If your pieces are joined at odd angles, you can choose to cut the pieces out at an angle, or just use a file to shape it later.

Step 3: Drill Some Holes

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Depending on the amount of curve in the pieces you're stitching, drill holes that will accommodate your Zip-ties anywhere from 3" apart to 6" apart, about 1/4" to 1/2" in from one of the piece's edges to be joined. This definitely does not have to be exact.



Now mock up the two edges to be joined, the one with holes in it and the one without. Try to clamp it as best you can for at least a few feet, especially if it's curved. Then, drill holes in the untouched piece that line up with the holes in the other piece. Again, this really does not have to be exact.

Even easier than epoxy is to use PL Premium construction adhesive. It comes out of a caulk gun and allows you to spread it like peanut butter. 24 hours later it is as hard as a rock. Just make sure you use gloves. You can make fillets just like with epoxy. I built a Puddle Duck Racer this way. The PL Premium is a polyurethane adhesive that sticks to almost everything, wood, metal, etc.

How does the PL Premium construction adhesive finish. Does it have a wood tone, is it clear, or is there some other appearance?

Thanks for the feedback hyper. Its probably not sandable either. Soo, I'll go with the epoxy method

Although you could probably cut the PL with power tools, I don't think you can really finish it. It is sort of a brownish yellow when it cures.

PL is awesome stuff. We used to have a lot of PL 400 around for gluing subfloors to joists, and we used it to strengthen our saw horses. Once the guy driving the Lull ran over one of the horses, and the wood broke before the joint glued with the PL.

chud94 months ago

I love the finish in the pictures. How did you pull that off? Did you use resin pigment for the epoxy and split it into different sections (one w/ pigment, one w/o) or did you use spray-on boat paint, or something else? I'd love to get mine looking like that.

Medic556 months ago

Good Job.

Fuddmaster7 months ago
What kind of plywood did you use? Curious if it is marine grade or not?
Z.Backas (author)  Fuddmaster7 months ago

I used two sheets of 1/4" Marine Grade Fir for the boat, and sealed it completely with epoxy.

Tanzer268 months ago
I built a Stevenson design "Weekender" back in the 80's. Also flat bottom and liked to round up when the winds picked up and she heeled over. Third year in the water, I modified the swing board to a fixed fin keel, moved the centre of resistance aft almost a foot and what a world of difference.
I don't know your sailing background,but boat balance is all about the centre of effort of the sail in relation to the center of sideway resistance of the boat. If you've ever been on a sailboard, moving the centre of effort is how you steer.
Sailing fairly flat is usually fastest, , I found the weekend we wwamted at least 5° heel. On your mini cup, modifying the centreboard is a no go, but getting the upper spar mor upright, moving the 2 mounting points forward or shortening the boom, would all move the CE forward. Letting out the boom, to flatten the boat, else moves the CE forward, but may sacrifice power.
I'd be curious how it would do with a sailboard type rig. Taller mast, shorter wishbone boom, also give you better headroom in the cockpit.
Tanzer268 months ago
Can you provide a link to the plans you used? I like the idea of converting to a sloop rig, it might balance better.
Tanzer26 Tanzer268 months ago
Wrong button. Your mast looks quite bendy. I you're rounding up too much when you heel, it could be a sail balance issue (ie too long a boom/not enough area ahead of the mast. Could also be some loss of depth of the rudder, so less area giving less control. generally, sailing flatter is faster, but you usually want a few degrees of heel.
Z.Backas (author)  Tanzer268 months ago

I just added the instructions I used in the last step as a .pdf file, hope that helps.

The mast in the picture was what I initially used because I was able to procure the material for free, though I soon learned that it was not nearly strong enough. I now have a 2.25" aluminum T6 mast that works perfectly, I recommend a material with at least a 2" diameter.

Though the sail is probably not perfectly balanced, I do believe that it's mainly the flat bottomed nature of the boat that causes it to head upwind when heeled. The boat simply needs to be sailed as flat as possible, it's as simple as that!

amajchrzak8 months ago
beautiful sailboat. I love buying and fixing up older boats. would love to try this.
jmwells8 months ago
Just a note: I'm an electrician. We use tons of zip ties. If you go to an electrical supply store, or an aircraft parts store; they sell a tool made for tightening and cutting zip ties. It looks like a gun, most have a tightness adjustment. When you've squeezed the trigger to the adjusted tightness it automatically cuts off the tail flush with the lock. No tail in the way, and, no sharp points to get snagged/cut on.
cesar harada9 months ago
thanks for the ectra step. That's helpful
cesar harada9 months ago

wonderful set of instructions. Inspirational. I want to build a few of these, but I want to make super super light... I'm in Hong Kong, so maybe bamboo + fiberglassed epoxy... I'll report for sure :)

Z.Backas (author)  cesar harada9 months ago

Check out the new step 8 epilogue I just added, a few modifications can shave pounds and improve sail-handling with ease!

The hull is simple enough, if you're going SUPER light I'd love to see a completely fiberglass or even carbon build!

I'm looking to build this same boat this spring, and would prefer to avoid the stringers as you did. How has this design held up with the different joining method?
Z.Backas (author)  balloondoggle1 year ago
She has proven seaworthy so far, and I think that the fiberglass joint will prove to be stronger than a stringer joint in the long run. Because the stitch-and-glue joint is inherently waterproof, whereas stringers require caulking, the fiberglass joint will maintain a seal for longer as well. I highly recommend the Mini-cup!
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