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By Richard Brewer - USA


I live in an area where there are dozens of ponds and lakes within a half hour drive. My wife is not keen on having a trailer in the yard, so consequently, I've got to be able to pick up any boat I build and put it in the bed of my truck, or put it on a truck rack. My boats have to be easy to build in that they don't require expensive tools or a master craftsman's hand. I don't care how long it takes. Other than fiberglass supplies, everything in my boats comes from one of several home improvement stores in the area. Since I glass everything, I use the cheapest materials possible, which up to this point has been 1/4 inch underlayment and pine trim.

I am looking to replace a 14' pirogue (see above) my wife and I have been using for the last five years or so. It only has about 7" freeboard when in the water, so I want something a little more sea worthy. I also want to be able to attach electric motor mounts to the boat; near the stern of the boat for those times when my wife is with me, and on the bow of the boat for when I want to fish by myself. So the new boat needs to be more robust structurally than what I have.

After reading a post on another forum a while back about Great Stuff, I decided to do some experiments using sandwich construction. I produced three samples, each 2 inches wide and 18 inches long. The first sample I produce using two strips of 1/8 doorskin separated by 3/4 inch and filled with Great Stuff. I had to use some small dowels to maintain the separation while injecting the Great Stuff. The second sample was simply two strips of the same doorskin glued to a 3/4 inch piece of Dow Styrofoam insulation using Elmer's wood glue. The last sample was a strip of the Dow glassed on both sides with 6 oz. cloth and epoxy. By far and away the doorskins on the Dow were clearly superior in rigidity, and provided a surface that would more readily take the weight of a person moving around the boat. The glassed over Dow had some give to it when squeezed.

I used Hulls (Carlson Design) to design the inner hull. The Hulls program allows you to arrange the parts onto a sheet(s) of plywood in any fashion you want, then gives you a set of coordinates on the sheet that you use to plot points along the lines of the parts. The lines are drawn by using a long piece of pine molding screwed down to the plywood along the points. I have used this program to build a number of other boats. The program is not too accurate in that it only generates six of seven points along the length of an 8 foot piece of plywood for each line, leaving some interpretation regarding where to place the molding between the points. As a result, once the parts are cut out, the port and starboard pieces have to be placed together side by side to assure that they are exactly the same dimension, and if they are not, one or the other has to be trimmed, leading to more inaccuracy. You get the shape of the boat you designed when everything is stitched together, but not exactly the dimensions you expected. The program is free, so I can't complain.

Because of the inherent inaccuracies of the design program, I realized that I would be in for a multitude of problems if I used it to design the outer hull as well. I thought it would be much easier to plank the outer hull, making adjustments in the individual planks as I went along, rather than trying to make major adjustments in large pieces. Since the planking would be glassed, I don't believe I gave up much strength using this method.

This boat would have to be turned several times during the course of construction, so it had to be built on a frame. The frame had to be as light as possible, so I constructed each section from 1/8 underlayment plywood, joining the sections together with two inch strips of the same plywood. The Hulls program provided the dimensions for three of the sections, but feeling that I needed more for rigidity, I used CAD Standard (free) to calculate the dimensions for four more sections. The sections were aligned by drilling a 1/8 inch hole in each section on the centerline a fixed distance from a line parallel to the bottom of the boat. I used a laser ($2.99 at Walmart) to align the sections fore and aft by shinning the beam through the holes, and a level for port and starboard alignment. As each section came into alignment, it was attached using the strips and hot glue.

Once the frame was constructed, I used the Hulls program to produce the parts for the inner hull. After I had these parts cut out and matched, I used them as templates to trace out the 3/4 Styrofoam that would be placed over the inner hull. I staggered the layout of the Styrofoam so that endpoints would not correspond to endpoints on the parts of the inner hull.

I used solid core copper wire from Radio Shack to stitch the inner hull together. As anticipated, the hull did not exactly match the frame, so I had to make adjustments in the frame to make a rigid fit. I did this by hot gluing some spacers to the frame in such a way so that they pushed up against the inner hull. I screwed small eyelets into the hull and used wire and small bungees to hold the hull against the frame, so that when turned upside down, the hull wouldn't move out of the frame. Once everything was secure, I applied an epoxy paste using flour as a thickener to the seams, and once that cured I removed the copper wires by heating them briefly with a propane torch and extracting them with pliers.

The hull was then turned over. I attached the Styrofoam by applying Titebond II exterior glue to the hull, placing the Styrofoam on the glue, and then screwing down the Styrofoam using 1 and 1/2 inch #8 hex head metal screws. I made my own fender washers out of 2X2 inch pieces of 1/8 ply.

Using this method produces a screw hole in the inner hull, which later had to be sanded, filled, and sanded again before it is glassed. For my next project I'm going to try the following method: I'll drill 1/2 holes in the Styrofoam. I'll then place the Styrofoam on the inner hull without glue. Into the holes I'll place a 2 inch piece of 1/4 in dowel by hot gluing it to the hull, but not to the Styrofoam. Once all the holes have a piece of dowel, I'll remove the Styrofoam, lay down the glue (the dowels remain glued to the hull), and place the Styrofoam back over the dowels. I think by using some of my fender washers and pinch-on clamps I can produce the needed pressure for a good bond. Once the glue sets I can just clip off or pull out the dowels.

A gap forms where the Styrofoam chines meet. On the bottom of the boat this gap was filled with a 14 foot piece of pine 3/4 inch quarter round. Holes were drilling in the molding and it was screwed to the inner hull. The holes were filled and the screw tips were ground down flush with a Dremel where they protruded the hull. That gap was nearly 90 degrees wide, so the quarter round worked nicely. Where the upper two chines meet, the gap is only about 45 degrees, so I had to fashion little six inch triangular prisms out of a fir 2X4 using my table saw. The prisms were glued in the gap with Titebond and epoxied end to end with the aforementioned paste.

The rest is pretty straight forward. I attached some fir pieces to the bow and stern to bolster strength there. I ripped the planks out of 1/8 ply and staggered them in their placement to maximize strength. They were screwed down with 3/4 inch #8 hex head metal screws, which were removed after the Titebond set, and the holes were filled with epoxy paste. The color of the plywood used is a very red luan, so I added a little powdered tempera paint to the paste in an attempt to match the color. Powdered tempera is a great way to add pigments to epoxy, or to use as a water based stain on wood before applying epoxy. I think it's about $3 for an eight once jar that lasts forever. I get mine from Discount School Supplies.

I covered the exposed Styrofoam where gunnels would normally be with a set of fir rectangular prisms in the same way that I filled the 45 degree chine gap, and sanded them round to cap off the top of the boat. The boat is now fully glassed inside and out. I am in the process of making the foredeck out of laminated 1/8 ply, along with the aft deck, which will be just big enough to provide a handhold when carrying the boat, and as an attachment point for lines. I still have to design the hangers for the seats and thwart, and the fore and aft motor mounts.

Structurally, the boat does not need a thwart, but having a quick detach thwart might aid in getting the boat up on the truck rack.

Email me if you want the .hul or the .dxf files, or anything else at:

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