Home Plywood Boat Building – Sew and Glue or Layer on the Frame?
There are two general modern techniques for building plywood boats at home: traditional construction, Ply on Frame, and the newer Stitch and Glue method. Each has its advantages and disadvantages. Both boat building methods are capable of producing very functional, strong and safe boats. The method of boat construction that a prospective boat builder should select depends as much on the skills, patience, and preferences of the builder as it does on the desired characteristics of the finished boat.
Let’s start by discussing the traditional method of building layers on frames. It is made by starting with wooden frames, sometimes called ribs. They usually have straight sides, however some older designs attempt to incorporate curves into the rib elements, complicating construction considerably. These frames are placed using a construction jig, usually oriented so that the hull is built upside down.
The longitudinal members of the frame are joined in grooves with notches in the ribs. The first is a heavy frame element called a keel that runs down the center of the ribs. At the bow end of this element, the vertical beam that forms the bow of the boat, called the bow, is attached.
Two longitudinal frame elements run along the upper edges of the hull, one on each side, called sheer braces. Two more elements are added, the curve of the ribs where the bottom of the hull transitions to the sides of the hull. This joint in the hull is called a bilge and the frame member installed here is called a bilge trunk. Depending on the size of the hull and the philosophy of the designer, additional longitudinal members can sometimes be specified to complete the ship’s hull structure.
Most often each of these joints are glued and bolted or sometimes bolted together. These days, high-strength synthetic adhesives, such as epoxy or the newer polyurethane adhesives, are great for bonded joints because, unlike the old natural, casein, or polyvinyl acetate glues, modern glues will hold even if the joints do not match perfectly. . They fill the gaps better.
The plywood board is then rested against the frame, cut slightly larger, glued and nailed (or screwed in place) and trimmed to the edges of the frame. Finally, the plywood is topped with one or more layers of fiberglass, or simply saturated with epoxy to improve strength, abrasion resistance, and water penetration.
Stitch and glue canisters, on the other hand, are constructed in a completely different way. These ships are built with precisely cut panels that will end up forming the shape of the hull. There is no internal frame, or if there is, it takes the form of bulkheads rather than frame elements. The builder uses designer-supplied full-size panel drawings or lays out the final shape of the sides and bottom of the hull in plywood flooring. Next, the flooring is cut. One side can be used as a pattern for the other, because it’s important to get both sides exactly the same shape and to keep the bottom very symmetrical.
Once the panels are cut, a row of small holes is drilled in the adjacent panels near the edge and copper wire or nylon ties are run through the holes to “join” the edges of the plywood. An epoxy mixture thickened with silica or microspheres is then placed into the joint to make a fillet and the joint is taped with fiberglass tape. The hull is turned over and similar joints are made on the outside of the hull. Then, if desired, the hull is covered with fiberglass.
Contrary to first impressions, a stitch and glue canister, if designed and built correctly, is just as strong and capable as its framed counterpart. They are just different philosophies in the making. Just as automobiles and aircraft have transitioned from framed and covered construction to more modern construction, unibody in the case of automobiles and monocoque in the case of aircraft, so naval architects have made the transition from framed to The stitched and glued for a lightweight and strong construction. , ships easy to build.
Now that you know how these ships are built, let’s talk about what kind of skills and personality the builder has, in order to select the right type of ship for him. First let’s take a look at carpentry skills. Do you like working with wood? Does planning a nice piece of hardwood bring you joy? Do you like the smell, feel and satisfaction of shaping wood? don’t laugh. This is a serious question. Some people will say, yes, that’s me. I love it! Some will say, no, not really. I see it as a means to an end and just want to finish.
If you’re in the first group, you love to work with wood, you probably have what it takes to make a framed boat. Requires woodworking and being careful with joint settings. It requires a bit of patience and a sense of pride in your workmanship.
If you’re in the second group, you should probably build a stitch and glue boat. They go together much faster with fewer steps. They also require less knowledge of carpentry and use of tools. You should still be able to cut plywood fairly precisely, but almost everything can be done with simple power tools.
Building a stitch and glue boat is a more complicated proposition than a cape on the frame hull. You have to mix and spread a lot of epoxy, usually wearing rubber gloves. If you scratch your nose, you’ll have to spend some nasty time with acetone to remove the epoxy as well. Working with wood, you just dust yourself off most days. Adhesives are used, but not to the extent of a pot of stitch and glue.
When sanding epoxy, you should wear a respirator to prevent epoxy and fiberglass dust from getting into your lungs. Sawdust isn’t as bad for your system, but I still wear a respirator when sanding large tracts of wood with a power sander.
Well, I hope this has helped you decide which of the two types of hulls to build. I highly recommend everyone to build a ship. It is a fun hobby and a great experience. It is also the father and son project. I can’t imagine a better experience for a child than learning woodworking by helping build a boat and taking him fishing.