OT: Seeking Plywood Boat Plans [long post]

I don't recall where he got the plans, but I believe he told me he built it from a single 4x8 sheet of 1/2" plywood, plus some other odds and ends of lumber. Over the years, as a kid, I spent plenty of lazy summer days fishing on Blue River in southern Indiana with Dad, and I want to try to relive some of those days, so I want to try to build a copy of his boat. After Dad died in '91, his storage space in the shed at the farm was appropriated for other uses, and the boat has become a victim of the weather.

I went out the other night to try to get some measurements from what's left of the boat, but I didn't get everything I needed because at a couple of places I could've used an assistant to hold the end of the tape measure in place. The sides of the boat are 12" high, and the bottom measurement is 86". The top measurement on the sides is longer, probably 4" in front and 3"-4" in the back...but due to the curve of the sides, I couldn't hold the tape in place.

The front panel measures 20-3/4" across the top, 16" in total height, and it tapers to 16-3/4" at the bottom of the sides, 12" from the top...then does a sharper taper to a point in the center, a total of 16" from the top.

The bottom of the boat is made in two halves, with a 1"x2" strip up the middle joining the halves. At the back, each side is 16" wide; it gradually curves to the widest point about 32" from the back, where it measures 19" wide...then curves back narrower toward the front to a final width there of 9". [Note: the difference in the width between the front of the bottom panel and the boat's front panel is accounted for by the curve in the bottom of the boat...it's NOT a flat-bottom boat.] I was unable to get the measurement of the bottom panels down the center due to the front-to-rear curve in the center of the boat...but the best I could determine, the center strip joining the bottom panels is approximately 87" long [allow for some error there].

The back panel measures 16" deep in the center, 12" at the side panel, 38" across the top, and tapering to 33" at the bottom of the boat sides.

Inside, the seats were made of boards 1"x9"...the longest one is in the widest point of the boat, just to the rear of the center of the boat, and it's 43" long. The entire boat also has a 1"x2" strip around the entire top perimeter on the outside, as well as a piece of 3/4" plywood added to the rear panel just above the back seat, where Dad attached his less-than-trustworthy 1/2 hp outboard (I'm thinking 3 to 5 hp would've been better suited, on a windy day). The bottom panels had TWO 1"x2"s down the center on the inside, and on the outside there was a 1" metal "dragging strip" down the center of the bottom, with space for a 1"x3" or 4" tapered keel board under it.

Has anyone else built a similar boat? Dad assembled his with brass screws, which is probably why there's still something left. The boat is light enough for one man to load and unload from a pickup truck, but it definitely works better with two people.

If anyone knows where I might find plans--or even better, assembly instructions--for a similar boat, I'd sure appreciate hearing from you. Now, somebody who's handy with "barnyard engineering" might be able to take the bits and pieces of info I've provided and figure out how to build that boat. At this point, ANY help I can get would be appreciated.

There are tricks to taking measurements off of a boat. I've seen it described in old WoodenBoat articles; I'm sure some of the boatbuilding books describe it as well. Suffice it to say you can't do it with just a tape measure. You have to measure the "offsets", which describe the curvature of the boat.

If you really like the size and shape of your dad's boat, you might be able to use it as a mold. You could wrap plywood around it, temporarily fasten each piece to the old boat, trim it to fit and remove it. Once you had each piece cut to size, you could then assemble the new hull over the old boat, then pull the new hull off, install the thwarts, etc and you'd have a boat just like dad's, just a little bigger.

A good book on plywood boats is H. H. Payson's "Instant Boats". See the link below for more information.

Some suggestions:

1. Use marine plywood. Regular exterior grade plywood has voids where water can collect. You can get away with exterior grade plywood if you sheath it in fiberglass, but then it would just be another (heavy) fiberglass boat. You can get marine grade fir plywood, but a better product is okume (african mahogany) marine plywood imported from Europe. It comes in millimeter thicknesses; my canoe is made from 4 mm (3/16") Okume. (There are several different brands, you can find them in WoodenBoat).

2. Although your dad used brass screws, you should really use silicon bronze. These are available from Jamestown Distributors (www.jamestowndistributors.com). You can probably buy bronze screws from Jamestown for less than what brass screws will cost at the hardware store. Jamestown also carries a variety of bronze boat nails and other products, be sure and get their catalog.

3. Presumably you're going to use some kind of adhesive. WEST System epoxy is very good, but maybe not the best choice for plywood-and-screw construction. A lot of boatbuilders use 3M 5200 polyurethane marine sealant. It does a great job of filling gaps and is quite flexible. Be sure and clean it up with acetone before it sets up, because once it sticks to something it's there forever. 5200 and WEST are both sold by Jamestown, plus a bunch of other adhesives.

One more thing: If you want the lightest, best-looking boat you can own, glued lapstrake plywood is the way to go. (My 11'6" canoe weighs 35 lbs.) The best book on this type of boat construction is "Ultralight Boatbuilding", by Thomas J. Hill. ISBN 0-87742-244-3

Good luck!

Google "Wooden Boat Magazine" they have plans for hundreds of boat designs, you might find one there that is similar.

I have books at home by John Gardner that have plans for small wooden boats. I will take a look to see if anything resembles what you described.

Years ago I built an 8 1/2 foot version of Howard Chapelle's pram in Gardner's book, Building Classic Small Craft, then powered it with a 1.2 Eska outboard. It gave 5 miles per hour, measured by the charts, regardless of load. Later I repowered it with a 2 cylinder Johnson 3 hp. The larger engine was much quieter and smoother, but it still gave the same speed, 5 mph. The pram, btw, appeared in the Launchings column of Woodenboat, issue 86.

If you can find 10' lengths of clear eastern white cedar, this is definitely the craft to build. If not, I've seen a number of Nutshell Prams around the waterway. Featured in Woodenboat Magazine, the design uses plywood with epoxy seams, and seems both simple to build and useful as a boat.