Plywood construction probably presents the easiest method for an amateur to build a good boat, but it is also useful a useful construction for a professional shop wanting to satisfy a customer who doesn’t have a large budget. It is a straightforward process and the plans tend to be easy to follow but there are a few tricks of the trade which I will try to cover.
The two boats covered here are quite different sisters from the same plan. The first, “Catspaw” was built on spec in 1981 specifically to enter in a floating boat show in Vancouver and give me a venue to market my business of custom yacht construction. I used it as a sales office to show photos of other boats and to sit and talk to potential customers. I had a great time but didn’t sell anything (Anybody remember the economy in 1981?) so Catspaw became my boat for several years. I didn’t mind that a bit.
The second, “Sylvester” was built on contract for a customer who loved my boat but wanted many aesthetic and practical upgrades. These made what had been a very economical build (Catspaw) into a quite pricey but lovely little yacht.
This photo shows just about everything that you need to build a 19’ Catboat, from portholes and plywood to glue and oil lamps.
Here the bottom (3/4” fir ply) is being scarfed up. If you stack your pieces in a staggered pile at a 1:8 ratio, ie: 6” setback for 3/4” thickness, and then plane the slope, you can glue them together and achieve the same strength as if the plywood had been made up full length. In this photo the end scarf is being cut and the side scarf has already been done. This will render a single piece of 3/4” plywood that is 16’ long and 8’wide (minus scarf width). Another small bit scarfed on at the front end and the whole bottom will be done. The trick here is to keep an eye on the gluelines in the plywood as they will guide you to an even plane if you keep them straight.
In this one the bottom and one side have been rough shaped and epoxy sealed on the inside prior to fitting on the jig frame just visible on the left. Yes, that’s Smaug, of course, on the right.
Now the sides have been fitted and fastened to the transom. (I don’t have any photos of it but it’s just a boring flat piece of 3/4” plywood) The stem has yet to be fitted. The line down the length of the plywood is just a veneer joint in the sheets as they came from the factory, but the faint vertical line you can see is a scarf.
This is a scarf, seen from the edge on one of the bent sides (1/2” ply). It’s a perfectly fair curve and maintains full plywood strength. It’s a little hard to see but it travels back left from the seam you can see on the face of the plywood. The notches you can see here in the jig will have the permanent chine pieces fitted before the sides are finally fastened at the stem.
Last photo for now. Here the sides, chines and stem are fastened and glued and the bottom awaits. Notice that the sides have been planed down fair and ready for the bottom.
(We replaced 52 ribs and several other parts in the big powerboat in the background left. That was fun!)
Next time we’ll get her off the jig and have a look at the keel, centerboard case and cabin features.
As always Thanks for watching.
All comments, questions, and critiques are welcome.
Napaman, this one’s for you.
-- Paul M ..............If God wanted us to have fiberglas boats he would have given us fibrerglas trees. http://thecanadianschooloffrenchmarquetry.com/