South Haven Dory Plans – Part 2

Sheer Clamps – A

Sheer clamps are the boards which strengthen the top of the hull. Right now, you are just going to put the outside sheer clamp on. I used 3/4″x1 1/2″ pine or fir boards which were sold as furring strips and were extremely cheap. 3/4″ is too thick, you may want to reduce the sheer clamp battens down to 5/8″ or even 1/2″, they will be easier to work with. The other dimension is less important for structural strength, anything between 1″ to 3″ would be OK, whatever you think looks nice. Next time I would use nominal 2″x4″ pine boards cut down to 1/2″x2″. There are three layers plus the hull width, so you will still get a strong sheer clamp with a narrow batten. I like the looks of a thick sheer clamp, but it’s definitely another area to remove some weight from the boat with no strength loss.

You will need to scarf pieces together to make 15’2″ pieces. There will be a lot of stress at the scarf area so make sure you are scarfing ends together with no weak knots or cracks. I used an 6″ scarf, trying to get 15′ out of two 8′ sections and one of my scarfs cracked so you might want to go with a 10″ or 12″ scarf with two scarfs per batten if you are using 8′ stock. I wasn’t too concerned about the crack, I just smeared epoxy/filler (molassess consistency) in and outside the crack, put a piece of saran wrap around it, and clamped a piece of furring strip next to it as a sister to make sure it cured with the right curve.

What, you don’t know how to scarf? Well, you probably should get a book on boatbuilding, but basically it is cutting an angle into the end of a stick, and cutting the same angle into the end of another stick, and gluing the two sticks together. When I talk about a 10″ scarf, it means to start the angle 10″ from the end of the stick. I drew a line which showed the area I wanted to cut off to make the angle, and then took a hand saw and cut it off. Then I took the orbital sander and smoothed it out and made sure both angles fit each other OK. Then I glued them with epoxy/filler and clamped them down so they made for a straight 15′ stick.

Gluing the outside sheer clamps is a matter of wetting the hull top and sheer clamp with epoxy and clamping the two together. Do one side at a time and have at least 10 clamps (more is better). Sometimes the batten doesn’t quite want to follow the curve of the plywood and you have to clamp it hard and bend it hard. If you have to fight it, you might want to let the sheer clamp take it’s natural shape and either carve off the additional plywood which sticks up after it cures or fill in the hole with more epoxy/filler and plywood after you add the inner sheer clamps. I had to do both on my boat, which means the top curve should be adjusted, but it wasn’t by much. The solution is to use battens that are not very thick. I will use 1/2″ battens on my next boat.

Cut the sheer clamps off flush with the hull at the ends, or if you like, you can cut it so the forward end is pointed, which is a little bit more difficult cut, but the boat would probably look better with a pointed sheer clamp. When the first outside sheer clamp has been installed and is cured, stand in the front of the boat and imagine the centerline as it passes through the sheer clamp. Cut the sheer clamp along the centerline. Before installing the second sheer clamp, cut the end to fit the first sheer clamp and use lots of epoxy/filler between the two.

If you don’t have enough clamps, there is another way. You will have to start by installing the inside sheer spacers (see below) and put them in to be able to use screws to hold the outside sheer clamp in place.

Are the outside sheer clamps cured? Good, let’s move on.

Glass the Bottom

Flip the boat bottom side up, and cut a piece of glass cloth exactly the size of the bottom. Don’t try to let it overhang the corners, it will create folds and will not lay right. Pour and brush clear epoxy on the glass and bottom until it is saturated. Let cure, then brush on more epoxy to fill the weave. You could glass the sides too, but be prepared for an increase in weight. I don’t think its worth it, because I want to be able to carry the boat on my own. For rough use on rocky rivers I might consider it.

Install Skeg

To cut the skeg shape, put a piece of 1/2″ ply on the aft part of the bottom. The skeg should start well aft of the lowest point (highest when upside down) of the bottom curve. Take a straight edge and draw what you think would be a good skeg. Then go to the transom, and extend the angle of the transom on to the skeg. Cut out the skeg triangle. Lay it on the hull and decide if you like it. If so, use it as a pattern to cut another 1/2″ plywood board with the same shape. Glue the two boards together to make a 1″ skeg. Round the outer edges of the skeg (but not the side against the hull) so they are very round. Line up the skeg on the hull so that it is in line with the centerline of the bottom. Make up five 4″ tape pieces a little longer than the length of the skeg. Paint the hull in the skeg area and the skeg with clear epoxy. Mix up some epoxy/filler (peanut butter consistency) and smear it where the skeg will be attached to the hull. Push the skeg down into the goo all the way till it touches the hull, and then cove the epoxy/filler. Add tape to the joints and brush on clear epoxy. Add more tape, the more layers across the top of the skeg, the better, this area takes a beating. If you can’t get the tape to bend around the back end, let it hang out and sand it down after it cures, and then put another layer on the back end. Let it all cure, sand, and brush on clear epoxy to fill the weave. If you think you need to add more tape to the back of the skeg or the top, do it.

Paint Bottom

Let the epoxy cure for at least a week. Brush on an oil-based enamel paint in the color of your choice. To do it right, you need five or more coats. At a coat a day, this takes a while to get done. Let the last coat dry a week or more.

Sheer Clamps – B

I’ll assume you have the outside sheer clamp installed. This design depends on the sheer clamp to hold the hull in shape. To make it look really authentic, and also to let water run out when you lay it on its side, you can use sheer spacer blocks. These are just pieces of the same wood that you use for the sheer clamps cut to a standard length, say 4″ or 6″. These parts are then glued on the inside hull top, aligned with the top of the outside sheer clamp, and are spaced a standard length from each other, say 3″ or 4″. The ends and the oarlock areas are made with 12″ blocks for strength reasons. I would suggest making the spacer blocks 3/4″ wide, but 1/2″ will work if that is what you have.

The inner sheer clamp is glued to the spacer blocks. The transom is a little difficult because it is rounded. I just glued straight battens across it and then sanded and ground them down to a rounded shape. Not fine cabinetry work but effective.

The ends and transom corners of the inner sheer clamp will have to be cut to join with an angle. I just look at them and imagein the centerline and maybe mark where I want to cut it and at what angle, and then use a handsaw to cut it. This is not accurate and leaves open spaces, so I put plastic tape around the bottom and side of the joint and try to shape the tape how I want the part to look and then fill the joint with epoxy/filler (molasses consistency). You could also epoxy a piece of fiberglass tape under the forward joint (breasthook?) for strength, or pour some epoxy/filler (molasses consistency) under the joint while the boat is upside down.

Seat Frame

There are two seat frames, forward and aft. The aft seat frame is located at 5’8″ forward of the hull bottom/transom joint, and the forward seat frame is located at 6’10” forward of the hull bottom/transom joint. Each frame is made of three parts, a seat base and two arms. The seat base is made out of 1/2″ ply cut to a width of 6 3/4″ (which is the height of the seat above the floor of the boat). The bottom of the seat base is cut to the width of the hull bottom, and the top width is the width of the hull sides at 6 3/4″ above the hull bottom. In other words, cut it to fit into the boat. I would suggest you use the centerline method, where you measure the distances, divide them in half, and plot the distances out on either side of a centerline. This gives you a pretty good chance that the part will fit the hull.

The arms are 3″ wide 1/2″ plywood, and are cut to taper from 3″ at the top of the seat base down to the width of the inner sheer clamp, where it touches the sheer clamp. The seat base goes inside the arms and holds up the seat. Install the seat base and arms by painting all mating surfaces with clear epoxy, then join the parts and hull with lots of epoxy/filler (peanut butter consistency). Clamp the seat base and arms together, then cove the joints. I did not use glass tape here, but you could. You can also do this in steps to make sure it fits right, for example epoxy the arms and base together while inside the hull, then install the assembly inside the hull. It should work OK either way. I added a cleat on the inside of the seat base to help hold up the seat and keep it from falling in when I tried to open it, but I am not sure that this is needed. I did not add limber holes. The advantage of limber holes is that you have only one puddle in the boat instead of three, but I personally would rather keep the mud and oar splash in the aft area so the front stays clean and I can lay down in it.


Cut a piece of 1/2″ plywood to fit inside the seat frame arms on the seat base, from hull side to hull side. The seat is just laid on the seat bases, no hinges or anything. It might be a good idea to tie it to the boat somehow, in case of capsize. At 14″ wide, I find the seat is wide enough to hold a 2 liter pop bottle full of water, a personal floatation device, small danforth anchor and line, plastic cup and sponge for bailing, and a cleanup rag. I also keep a couple of boat cushions up front to lay on and watch the sky at anchor, one of my greatest joys in life.

Foot Rest

The foot rest is also 1/2 ” plywood, and is just a mini frame which goes 5″ up the hull side, and 5″ along the hull bottom. Use a bevel guage or two pieces of wood to figure out the angle of the hull. The top is curved in a way that I imagine will give me two ways to brace my feet, high and low. I put the foot rest into the boat vertically. I located the foot rests at 3’2″ forward of the hull bottom/transom joint. This is for a six foot tall person, I suggest you get in the boat and check to make sure your foot rest location fits you. Install the foot rests by painting all mating surfaces with clear epoxy, then join the parts and hull with lots of epoxy/filler (peanut butter consistency). Cove the joints and add a small amount of glass tape and epoxy, at least on the forward side.

I’m sure that there are many ways to make a foot rest. The advantage of this style is that it serves to strengthen the hull.

Paint Interior

Lightly sand any rough spots, and paint with oil based enamel. I covered the seat board with epoxy and plan to varnish the seat board, but the rest of the boat is all gloss white oil-based enamel. Maybe I will put a blue stripe on it to make it pretty. The paint takes a while to dry, you can add a new coat every day, but expect to wait a week for the final coat to be dry enough to use.


I used a pair of bronze ribbed horn oarlocks, (Defender 2001, p. 169, Item 450626) and a pair of bronze top mount sockets, (Item 450631). I also tried the round horns, they did not work well due to the angle of the sheer clamp. You may have made a mark on the centerline of the hull bottom for positioning the oarlocks (see Bottom Panel cut out plan). It’s important to check to make sure that the oarlocks are 14″ aft of the aft edge of the seat. I centered the sockets in the sheer clamp, which means drilling directly adjacent to the hull side, take care. I tie a loop of line to the bottom of the oarlock and then use a figure eight knot to keep the oarlock from falling out if capsized.


I have 6 1/2′ oars from West Marine. Seven foot would probably work better. I did not put leathers on them, I just wrapped 10″x12″ glass cloth and epoxy around the area where it rubs against the oarlock. I don’t know if this works so you might just want to use the traditional leathers. I hold the oars in place by tying a line around the oar with a series of tight rolling half hitches and then bringing the line up around the oarlock and tying it off on an opening in the sheer clamp. By adjusting the knot at the sheer clamp, you can put the oar at the precise extension out that you want. This method also secures the oars to the boat.


I intend to drill a hole low on the aft seat base to fit my favorite fishing rod. I might have to add a layer or two of plywood on the inside of the seat base to make sure the rod stays at the right angle. I want it to stick straight back with the tip about 3′ over the back of the boat. The pole has to be kept low out of the way of the oars, but thats OK, then I don’t have to look up to see if I have a fish. Fishing is a great excuse to get on the water. “Honey, I’m going fishing, see you later!” echoes back with “Good riddance, I’m going shopping”. No questions asked, just do it. Even if you don’t like to fish I suggest you get a license and a cheap fishing rod, and the biggest, most outrageous fishing lure that most normal size fish run in fear from. Why? The bigger the lure is, the more macho the fisherman. By rowing up and down the harbor dragging your ridiculous lure, the motorboat crowd will think you are the most rabid fisherman out there and will steer clear, thinking that you are second cousin to Popeye. The 100+ hp fisherman types will throw you an extra salmon now and then, just because anyone who ROWS to troll has got to be a real die-hard fisherman. And when a fish bites your oversize ridiculous looking lure, it will probably be the biggest fish in the harbor and it will tow you around for an hour.


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