The Stitch and Glue Boatbuilding Method is an Easy way for a Beginner to Make a Plywood Boat
In a nutshell Stitch and glue boatbuilding has 4 major steps.
- Plywood parts of the boat are measured and cut according to plans. Small holes are made around the edges of the pieces.
- Wire is used to temporarily tack the boat parts together by stitching the plywood through the small holes. It's very much like putting a puzzle together or sewing clothe.
- Thickened Epoxy and fiberglass is used to strongly glue and reinforce the edges of the joints.
- Once the hull is made and rigid then the boat is braced and finished. This includes gunnels, seats, daggerboard wells etc. flotation enclosures, sailing fixtures.
Advantages of Stitch and Glue Boatbuilding Method
Stitch and Glue method can be used to make small dinghies, kayaks and canoes or large and elaborate boats. Because of its simplicity it has allowed relatively unskilled beginners to make good strong beautiful boats without a large number of tools or highly developed woodworking skills.
Many designers are offering plans for stitch and glue plywood boats. I have some plywood boat plans links here. Some plans are free. A large number of traditional designs are being re-designed to be suitable for stitch and glue method of boatbuilding. Designers will have wooden boat plans for beginners and less experienced builders, and will clearly indicate this.
Another advantage of the stitch and glue method is that it allows plywood, which is relatively easy to come by, to be substituted for high quality lumber, which is much more expensive and hard to obtain. Plywood is graded and Marine grades of plywood are uniform in quality and highly resistant to water damage.
Besides being an easy method of boatbuilding and allowing boatbuilders to use more commonly obtainable materials, stitch and glue offers another significant benefit to boatbuilders. Because less structure is required in stitch and glue, the finished boats can be much lighter than traditionally built boats. By carefully controlling materials the weight saving can be quite outstanding.
How to Build a Stitch and Glue Boat
First step is to decide what kind of boat you want.
You will need to answer some questions such as:
- What will the boat be used for, sailing, canoeing, rowing, fishing, kayaking? Is it going to be a tender to a larger boat, or will it be the larger boat?
- How many people should your boat be able to carry safely?
- Where will you sail your boat, and how will you get it there? Trailer, top of the car, permanent mooring, launching dolly.
- What is the boat budget?
- Will anyone help you build it?
- What kind of conditions will you will use your boat in? Lot of current, wind, quiet shallow water.
- Where will you build, epoxy needs some heat to set.
- What tools do you have?
- Why do you want to build a boat? fun, learning, experience, want a beautiful boat, just want to get on the water.
Once you have answers go looking at plans, surf, join Yahoo groups, there are dozens of groups and forums on boat and boatbuilding. The wooden boat forum is a good place to start.
Unless you have an exceptional idea for a boat design, it's better to go for already tested plans. There is no reason to re-invent the wheel. It is also interesting to note that building your own boat is not necessarily the least expensive way of getting on the water. There are many inexpensive boats offered for sale and it's easy to pick up a bargain particularly in the fall. Check Kijiji and Craigslist for starters. If there are boat clubs in your area go and visit and ask if anyone is getting rid of a boat.
Buying a kit is another good way to start. It simplifies the project considerably particularly if you have trouble getting adequate materials in your area. Surprisingly there is not a great deal of savings if you buy your own materials and work from plan rather than from a kit. The kitmaker benefits from volume purchasing which you will not get. Typically a kit will have the main parts of the boat cut out and suitable materials to make the details.
Get your tools together
You don't need a lot of tools but you need a few. I have a page about tools needed in boatbuilding.
Spend a bit of time sharpening the chisels and the planes, oiling the clamps and just making sure that your tools are in order.
How to Build a Stitch and Glue Boat, Go Shopping!
Once you have your plans, you can get your materials. First read your boat plans carefully and if they do not have a list of materials make one. It's very useful to have a full list at the beginning so that you can avoid having to keep going back to the shops.
Many boat builders out there want to get out on the water as cheaply and quickly as they can and will use inferior material, or take a chance on unproved plywoods. The Puddle Puck Racer builders often take this view and have a great time doing it. Stories abound about builders using cheap plywood and then when it gets wet having the boat delaminate.
My personal preference is to use good materials and have the boat last longer. At the very least use exterior grade plywood if you can't find or can't afford marine ply. Exterior might have voids inside but the glue will be good. The same goes for epoxy and paint, use quality materials when building your boats.
it's worth noting that you will need a number of other expendables such as popsicle sticks, plastic gloves, cheap paint brushes, sandpaper, mixing bowls. Keep your eye out for dollar store bargains. Also ask your relatives to hang on to yoghurt and margarine containers. If you have to buy them in the boat boutiques it can add up tremendously.
Epoxy makes stitch and glue possible because of its strength. Although some builders (such as Dynamite Payson) sometimes used polyester resin most amateur stitch and glue boat builders use Epoxy. Unlike polyester and hardener catalyst, epoxy is almost odourless and can be used inside. Epoxy comes in 2 parts that have to be mixed in exact proportions. Polyester resin is hardened by dropping a few sprinkles of Methyl Ethyl Ketone Peroxide (mikpik). AVOID POLYESTER RESIN if you can. it's not as easy to control, does not stick to wood as well and is more likely to trigger nasty allergic reactions. Epoxy is more expensive but worth the price.
There are many different types of Epoxy and it is very confusing for beginning boat builders. Essentially your choice should be the speed of setting. Using a slower hardener will buy you time. Quicker setting hardeners will shorten the build time. In very warm weather use slower setting to counteract the temperature. IF it's quite cold then use a hardener that is faster. You can even buy a colder setting hardener now. There are many brands available. I use MAS but West is well liked.
Scarfing the Plywood
It's a sad fact of boatbuilder's life that plywood comes in 4 x 8 feet panels. In Europe there are slightly longer ones, but most boatbuilders have to learn to join sheets together to make larger pieces. This is called Scarfing.
The classic way of scarfing plywood is to cut, grind, rout or sand a slope on each side of the sheets to join and to overlap and glue the slopes using epoxy. The overlap should be 8 times the thickness or more.
The photo shows how I cut the pieces while building my Skerry. I've clamped the 2 pieces of plywood on top of each other, then used a small block plane to cut the slopes. Using a block plane is easy and fast. Once the bevels are cut, they are glued with epoxy thickened with silica. Once the epoxy has set the joint is as strong as the plywood. Often stronger. It may bend slightly differently.
Dynamite Payson has developed a method of butting the pieces together and gluing them using epoxy and reinforcing fiberglass top and bottom. Many boatbuilders have used this method successfully.
How to Build a Stitch and Glue Boat, Mark and Cut
Carefully measure and draw the various parts of your boat on your plywood. This is called lofting. (Some plans actually give you full size plans)
Usually the plans will give you a series of points which you measure and mark on the plywood. You then put small nails on the points and join using a long flexible piece of wood. This is sometimes called a batten. This gives you a smooth curve joining all the points. Mark this carefully.
It's very helpful to transfer all reference points onto your plywood BEFORE putting your boat together. You will want the centerline, the position of any bulkhead and seats, the centerboard case position, the waterline or any other significant point. Also mark inside and outside, left and right, bow and stern of your boat. Once the pieces are cut out they don't look like anything until you start assembling the boat.
Using a saw, this can be a jig saw, or one of the smaller circular saw, cut out your parts.
It is possible to cut out by hand using a handsaw. It would just take longer but it would work just as well.
Because the epoxy that is used to glue the pieces together can be filled to make quite a thick filling paste, it does not matter if you make slight mistakes and gaps are formed when you assemble your boat parts. These will be filled and not show when you glue your boat. More accurate is better but not a dealbreaker. Stitch and glue is a very forgiving method of boatbuilding for beginners.
Using sandpaper, a wood file, or a small plane, smooth the cut up to the line if you have cut your part a bit big. Don't sand it smaller if you have cut smaller than your line.
Transfer any important mark to the flat pieces if you have not done so already while lofting the boat. It's hard to measure on a curve after the boat is assembled. Do a quick check of your measurements. It's also helpful to mark the front and back and left and right on each piece. it's not always obvious when you are assembling.
Lay the parts down flat and mark points along the edges where 2 pieces will go together. I usually choose a corner and start measuring every 6 inches or so. I put a small pencil mark about a centimeter in. Adjoining pieces get marked. In order to make sure the holes align correctly start marking from the same corner on the parts that will be stitched together. Put them side by side if you have any doubts and check your little spots. Once you are satisfied that they are lined up reasonably well then drill them with a slightly larger drill bit than the diameter of your wire.
Prepare a number of short pieces of wire, I like about 5 inches long. These will be your stitches.
Some people use copper wire, some steel, others prefer plastic zip ties. Copper can remain in the boat and just gets ground smooth. Steel should be removed. I prefer steel wire because it is stronger and I seem to break copper or brass more easily.
Stitch and Glue Boatbuilding, Stitching
The next step is the most exciting for me because this is where your flat plywood boat parts become a boat.
Starting at one end I count the same number of holes on both sides and put my first wire roughly in the center of the part. I then gradually wire the 2 parts together. I've marked my parts so I know which side is in and which side is out. I also know front and back. The wires don't need to be tight at this point. it's better to loosely twist them until you have the boat assembled.
An extra pair of hands is helpful. It is also more comfortable to work on a table or on sawhorses or short benches. Sooner or later you will look at your work and see a boat shape taking form.
Stitch and Glue Boatbuilding, Gluing
The boat on the left is now stitched together and is ready to be tacked. Plans fit together slightly differently. Sometimes the designer wants you to overlap the pieces. Sometimes the plywood is to be assembled corner to corner. Whatever your plan suggests make sure the plywood is in the correct position. Tighten the wires where necessary. The corners usually need some wiggling and adjusting. I use a putty knife and tongue depressors to position my pieces better. A small gap is good and allows the epoxy glue to touch all the surfaces.
If you need to make more holes for extra wires go ahead, that sometimes makes it easier. Once everything is in place measure your boat corner to corner diagonally. The 2 diagonals should be the same length. If they are not then push and wiggle your boat till they are. This is very important. Then make sure the boat is level by using a level on the bottom. You want the front to be level across the boat and the back corners to be level. This will prevent your boat from hardening twisted. Note that it makes no difference if the boat is not level front to back since that is not twisting the shape.
Once your boat is nice and level and the diagonals (the distance between opposite corners ie left front to right back corner, and left back to right front corners ) are equal and the pieces are fitting reasonably well together and the boat is symmetrical, then you are ready to glue.
Mix up a small batch of epoxy thickened with silica or fibers. In this boat I used a mixture of silica (cabosil) and a small amount of sawdust. I prefer the texture of a small amount of sawdust adds. It's mostly silica though. The epoxy should be thick enough so it does not flow but not so thick that it won't stick to the boat. You should be able to take it up on your spatula and butter it on your seam and it stays there without dripping down.
There is a great deal of mystery as to what silica is. Here is my page on fumed silica also known as coloidal or amorphous silica.
Getting the right consistency takes a bit of practice but really is not so critical. If the thickened epoxy flows down just add some thickener. IF it's so thick that it feels really dry and can't be spread you need to quickly add a bit of mixed epoxy to soften it up. I normally measure up a few small containers (dollar store shooter glasses) full of pre measured but not mixed epoxy so that if I need to, I can quickly put a small batch together. If you bought automatic pumps with your epoxy then it's easier.
At this stage you have to get the epoxy right. Measure carefully and scrape down the sides of your measuring containers. You can use the automatic pumps, or measure by volume but it has to be quite accurate. You must also mix your epoxy before you thicken it. Scrape the corners well and take your time.
Before adding the silica but after mixing your epoxy, put aside a small amount and use this more liquid epoxy to wet the spots you will be gluing. I find that plywood sometimes absorbs quite a lot of epoxy on the edges so I like to wet them first with a small brush dipped in epoxy. Use slower epoxy when you first start. It gives you longer working time so you are not so stressed.
Using a popsicle stick or a small spatula, go around and tack your seams carefully between the wires. What you are doing is gluing the pieces in position. If you plan to just grind the wires off instead of removing them you can get epoxy on the wire. I prefer to remove the wires so I glue between first then remove the wires when the epoxy has set, and go around again and fill the spots where the wires were.
Once you've spot glued your boat (usually from the outside first) then check your alignment, make sure your boat is level and DON'T touch anything. Just let it set.
On the right, a bulkhead is being wired in. Often the bulkheads are wired in before the hull is tacked with thickened epoxy. In this case the boat was very simple and it did not matter. Follow your plans. Once the epoxy has set your boat will start getting more solid feeling and rigid.You have now mostly set the shape of the hull. You can remove the stitches and fill the spots where the wires were, or you can grind the wires that stick out.
it's nice to get the wires out because they tend to be scratchy and snag you as you go by.
Each new part that you add gets glued in with thickened epoxy. You will be adding daggerboard frames, mast step and partner, coolers, corner reinforcements, gunwales.
Each finished seam will get a fillet of thickened epoxy. Getting a smooth curve is an art! Luckily an ugly fillet is just as strong.
This is very similar to a bead of caulking around the bathtub. This fillet makes a radiused edge that can be covered with fiberglass tape or the boat can be covered entirely with fiberglass cloth. The fillet adds a great deal to the strength to the joint. It covers any error you might have made while cutting and it gives a nice finish to the corners. I usually make mine with epoxy thickened with sawdust, and just a small amount of silica to make it easier to spread. It makes it harder to sand but nicer to apply.
You can use a tongue depressor, or the back of a spoon to smooth out the fillet to a nice curve.
Try to make your seams and fillets as smooth as you can. It's tedious to sand them smooth and they can look not so nice. In order to strengthen and waterproof, the whole boat usually gets covered in epoxy even if you don't plan to use fiberglass cloth all over.
If you plan to varnish your boat instead of painting her, go around and erase any pencil mark you made otherwise it will show through the varnish.
There is no obligation to do everything at one go. You can stop and start again later. What is essential is to make sure your boat is level and is not setting up in a twisted position. Keep your tape measure and level handy and use them every time you add epoxy to anything.
Depending on the plan, there is often fiberglass cloth reinforcement added. At least the seams get covered as does the bow. Often the whole boat gets a coat of cloth inside and out. Cloth comes in many thicknesses and virtually disappears after it is coated with resin. Fiberglass cloth adds weight but also tremendous strength.
Adding all the small parts takes as long or longer as making the boat shape.
The epoxy is an extremely strong glue and is usually stronger than the wood itself.
As in any project the finishing, painting or varnishing takes quite a lot of preparation including sanding, priming and painting. Whenever you drill a hole in the boat to attach an oarlock, cleat, rudder hardware, seal the hole so that your boat remains waterproof. I try to make my holes at one sitting and go around with epoxy and squeeze it in the holes using a small syringe. Also use bedding compound and use it as you put the various pieces of hardware on. Don't use silicone. It gets onto the boat and prevents paint or varnish from sticking. It is almost impossible to get off. 3M makes 4200, Dolphinite is another bedding compound.
For more detailed photos of the stitch and glue method of boatbuilding see my day by day record of building the Apple pie Dinghy and the building a Skerry Sailboat.
Both the Skerry and the Apple Pie Dinghy were built using the stitch and glue method of boatbuilding. I had never built a boat before I built my Skerry.
My website has many articles on various aspects of Boatbuilding and links to resources. Check out my boatbuilding links page.
I try to be accurate and check my information, but mistakes happen.email me if you find mistakes, I'll fix them and we'll all benefit: Christine