Home Plywood Boat Building: Stitch and Glue or Ply on Frame?

There are two general modern techniques foris drilled into adjacent panels close to the edge
building plywood boats at home: the traditional, Plyand either copper wire or nylon tie-wraps are
on Frame construction and the newer Stitch andthreaded through the holes to "stitch" the
Glue method. Each has its advantages andplywood edges together. Then an epoxy mixture
disadvantages. Both methods of boat constructionthickened with silica or microspheres is puttied into
are capable of producing very functional, strong,the joint to make a fillet and the joint is taped
and safe vessels. Which boat construction methodover with fiberglass tape. The hull is flipped over
a potential boat builder should select, depends asand similar joints are made on the outside of the
much on the skills, patience, and preferences ofhull. Then, if desired, the hull is fiberglassed.
the builder as on the desired characteristics of theContrary to first impressions, a stitch and glue
finished boat.boat, if properly designed and built, is just as
Let's begin by discussing the traditional ply onstrong and capable as its framed counterpart.
frame construction method. It's done by startingThey're simply different philosophies in
with wooden frames, sometimes called ribs.construction. Just as cars and aircraft have
These are usually straight sided, however somechanged from framed and covered construction
older designs try to incorporate curves in the ribto more modern, unibody in the case of cars, and
elements, complicating the constructionmonocoque in the case of aircraft, construction,
considerably. These frames are positioned using aso naval architects have been transitioning from
construction jig, generally oriented so that the hullframed to stitch and glue construction for light,
is built upside down.strong, easy to build boats.
Longitudinal frame members are attached intoNow that you know how these boats are built,
notched slots in the ribs. The first one is a heavylet's talk about what kinds of skills and personality
frame element called the keelson that runs downthe builder has, in order to select the right kind of
the center of the ribs. To the forward end of thisboat for him. First let's look at woodworking skills.
element, the vertical timber that forms the prowDo you like to work with wood? Does planing on
of the boat is attached, called the stem.a nice piece of hardwood bring you joy? Do you
Two longitudinal frame elements run along thelike the smell, the feel and derive satisfaction
upper edges of the hull, one on each side, calledfrom shaping wood? Don't laugh. This is a serious
sheer clamps. Two more elements are added thequestion. Some people will say, yes, that's me. I
bend of the ribs where the hull bottom transitionslove it! Some will say, no, not really. I see it as a
to the hull sides. This joint in the hull is called themeans to an end and I just want to get done.
chine and the frame member installed here isIf you're in the first group, loving to work wood,
called the chine log. Depending on the size of theyou probably have what it takes to make a
hull and the designer's philosophy, sometimes,framed boat. It requires woodworking and being
additional longitudinal members may be specifiedcareful about joint fits. It requires some patience
to complete the boat hull framing.and a sense of pride in your workmanship.
Most often each of these joints are glued andIf you're in the second group, you probably should
screwed or in somtimes, bolted together. Thesebuild a stitch and glue boat. They go together
days, high strength synthetic adhesives, such asmuch faster with fewer steps. They also require
epoxy or the new polyurethane adhesives makeless woodworking knowledge and use of tools.
an excellent for bonded joints because unlike theYou still have to be able to cut out plywood fairly
older natural, casein, or polyvinyl acetate glues,precisely, but almost everything can be done with
the modern glues will still hold even if the jointssimple power tools.
aren't perfectly matched. They fill gaps better.Building a stitch and glue boat is a messier
Next the plywood planking is leaned against theproposition than a ply on frame hull. You have to
framework, cut a bit oversized, glued and nailedmix and spread lots of epoxy, usually wearing
(or screwed in-place) and trimmed to the edgesrubber gloves, If you scratch your nose, you're
of the framing. Finally the plywood is finished offgoing to have to spend some unpleasant time
with one or more layers of fiberglass, or simplywith acetone getting the epoxy off too. Working
saturated in epoxy to improve strength, abrasionwith wood, you just dust yourself off most days.
resistance, and water incursion.There are adhesives used, but not to the extent
Stitch and glue boats, on the other hand are builtof a stitch and glue boat.
in an entirely different manner. These boats areWhen you sand epoxy, you should wear a
built using precisely cut panels that will end uprespirator to prevent epoxy and fiberglass dust
forming the shape of the hull. There is no internalfrom getting into your lungs. Sawdust isn't as
framing, or if there is, it takes the form ofdamaging to your system, but I still do wear a
bulkheads rather than frame elements. The builderrespirator when sanding large expanses of wood
uses either full sized panel drawings supplied bywith a power sander.
the designer, or lays out the finished shape of theWell, I hope this has helped you decide which of
sides and bottom of the hull on the plywoodthe two types of hulls to build. I would strongly
planking. The planking is then cut out. One sideencourage everyone to build a boat. It's a fun
may be used as a pattern for the other, becausehobby and a great experience. It's also the parent
getting both sides precisely the same shape andand child project. I can't imagine a better
keeping the bottom very symmetrical areexperience for a child than to learn woodworking
important.by helping to build a boat and take it fishing.
Once the panels are cut out a row of small holes