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

There are two general modern techniques for buildingdrilled into adjacent panels close to the edge and
plywood boats at home: the traditional, Ply on Frameeither copper wire or nylon tie-wraps are threaded
construction and the newer Stitch and Glue method.through the holes to "stitch" the plywood edges
Each has its advantages and disadvantages. Bothtogether. Then an epoxy mixture thickened with silica
methods of boat construction are capable ofor microspheres is puttied into the joint to make a
producing very functional, strong, and safe vessels.fillet and the joint is taped over with fiberglass tape.
Which boat construction method a potential boatThe hull is flipped over and similar joints are made on
builder should select, depends as much on the skills,the outside of the hull. Then, if desired, the hull is
patience, and preferences of the builder as on thefiberglassed.
desired characteristics of the finished boat.Contrary to first impressions, a stitch and glue boat,
Let's begin by discussing the traditional ply on frameif properly designed and built, is just as strong and
construction method. It's done by starting withcapable as its framed counterpart. They're simply
wooden frames, sometimes called ribs. These aredifferent philosophies in construction. Just as cars and
usually straight sided, however some older designsaircraft have changed from framed and covered
try to incorporate curves in the rib elements,construction to more modern, unibody in the case of
complicating the construction considerably. Thesecars, and monocoque in the case of aircraft,
frames are positioned using a construction jig,construction, so naval architects have been
generally oriented so that the hull is built upside down.transitioning from framed to stitch and glue
Longitudinal frame members are attached intoconstruction for light, strong, easy to build boats.
notched slots in the ribs. The first one is a heavyNow that you know how these boats are built, let's
frame element called the keelson that runs down thetalk about what kinds of skills and personality the
center of the ribs. To the forward end of thisbuilder has, in order to select the right kind of boat
element, the vertical timber that forms the prow offor him. First let's look at woodworking skills. Do you
the boat is attached, called the stem.like to work with wood? Does planing on a nice piece
Two longitudinal frame elements run along the upperof hardwood bring you joy? Do you like the smell,
edges of the hull, one on each side, called sheerthe feel and derive satisfaction from shaping wood?
clamps. Two more elements are added the bend ofDon't laugh. This is a serious question. Some people
the ribs where the hull bottom transitions to the hullwill say, yes, that's me. I love it! Some will say, no,
sides. This joint in the hull is called the chine and thenot really. I see it as a means to an end and I just
frame member installed here is called the chine log.want to get done.
Depending on the size of the hull and the designer'sIf you're in the first group, loving to work wood, you
philosophy, sometimes, additional longitudinal membersprobably have what it takes to make a framed boat.
may be specified to complete the boat hull framing.It requires woodworking and being careful about joint
Most often each of these joints are glued andfits. It requires some patience and a sense of pride in
screwed or in somtimes, bolted together. Theseyour workmanship.
days, high strength synthetic adhesives, such asIf you're in the second group, you probably should
epoxy or the new polyurethane adhesives make anbuild a stitch and glue boat. They go together much
excellent for bonded joints because unlike the olderfaster with fewer steps. They also require less
natural, casein, or polyvinyl acetate glues, the modernwoodworking knowledge and use of tools. You still
glues will still hold even if the joints aren't perfectlyhave to be able to cut out plywood fairly precisely,
matched. They fill gaps better.but almost everything can be done with simple
Next the plywood planking is leaned against thepower tools.
framework, cut a bit oversized, glued and nailed (orBuilding a stitch and glue boat is a messier proposition
screwed in-place) and trimmed to the edges of thethan a ply on frame hull. You have to mix and spread
framing. Finally the plywood is finished off with one orlots of epoxy, usually wearing rubber gloves, If you
more layers of fiberglass, or simply saturated inscratch your nose, you're going to have to spend
epoxy to improve strength, abrasion resistance, andsome unpleasant time with acetone getting the
water incursion.epoxy off too. Working with wood, you just dust
Stitch and glue boats, on the other hand are built inyourself off most days. There are adhesives used,
an entirely different manner. These boats are builtbut not to the extent of a stitch and glue boat.
using precisely cut panels that will end up forming theWhen you sand epoxy, you should wear a respirator
shape of the hull. There is no internal framing, or ifto prevent epoxy and fiberglass dust from getting
there is, it takes the form of bulkheads rather thaninto your lungs. Sawdust isn't as damaging to your
frame elements. The builder uses either full sizedsystem, but I still do wear a respirator when sanding
panel drawings supplied by the designer, or lays outlarge expanses of wood with a power sander.
the finished shape of the sides and bottom of theWell, I hope this has helped you decide which of the
hull on the plywood planking. The planking is then cuttwo types of hulls to build. I would strongly
out. One side may be used as a pattern for theencourage everyone to build a boat. It's a fun hobby
other, because getting both sides precisely the sameand a great experience. It's also the parent and child
shape and keeping the bottom very symmetrical areproject. I can't imagine a better experience for a child
important.than to learn woodworking by helping to build a boat
Once the panels are cut out a row of small holes isand take it fishing.