Centerboard Saga

I have spent the past few weeks building the centerboard for my Penobscot 14. Sailboats must either have a centerboard, or a dagger board (like a centerboard only not permanently encased in the boat), or, as is common in large sailboats, a deep keel. These structures provide the needed counter resistance against the water as the wind hits the sail. Pressure from wind and counter pressure from water against the boat and the under water centerboard provides the forces needed to propel the boat forward. This is a simplified explanation...the physics of sailing  are more complex and interesting than that. Anyway..back to MY centerboard. First there is the board, which I made by edge glueing two 3/4" thick 40" long pieces of red oak. Oak is a good choice for centerboards and rudders....nice and strong when under pressure from water. The pattern for the board, rudder like in shape was laid out, the board then cut out and the board then shaped to a a taper on both sides so that the shape of the surfaces was convex. I then applied epoxy glue with fiberglass to the board, cut out a 3/4" hole for the handle and a 3/8" hole for the pivot bolt. This pivot bolt hole was reinforced with a section of copper tubing. The board looked good.

   Now the case for it. This was a complex structure to build that required forethought as certain things needed to be done in correct order, such as preparing the inner surfaces of the plywood forming the sides before putting the case together. Once the case is put together you can't get to these inside surfaces to apply protective and waterproofing epoxy glue. The bottom of the case has two 3/4" x 3/4" strips of wood that are attached at the base of the case to provide structure to attach the case to the keel. Before permanently ataching these, I drilled the holes that would be needed to screw the case into the keel.  Had I tried drilling these holes after putting the whole case together I would have not ben able to drill these holes straight up and down a the sides of the case would have been in the way of the drill.  The bottom of the case must also be shaped to account for the curve of the keel and the case must fit accurately over the centerboard slot in the keel. When the centerboard is functioning it comes down through the slot just adjacent to the port side of the deadwood at the bottom of the boat. After much measuring and fussing I got it all together. Fore thought in boat building is essential...if you don't anticipate potential problems in construction you will inevitably have unwanted moments and stress. I learned this early on in the construction of this boat with early mistakes that caused me much waste in time and material as I had to re-do steps.The case fit beautifully on the keel, covering the slot exactly as it should. I tried a dry fit with the centerboard bolted into the case and found that I had not made the board thin enough to allow free swinging motion through the case and slot. So out came the sander and off came most of that beautiful fiberglass and epoxy coating. I finally got the board thin enough and a 2nd dry fit test run demonstrated good movement of the board through the case and keel opening. I will have to re-coat and re-glass the board to protect it from the water. The case is now ready to be glued and screwed into place. I may start that tomorrow but I plan on being very cautious with that process as a perfect installation is need to prevent leaking. According to Arch, the secret is to use lots of epoxy glue in addition to the screws to get a water tight fit. I will! After the case is installed I'll pt the center thwart in, as it sits on top of the back of the centerboard case and two risers installed in the hull. Then on to the side seats, front thwart and the final touches tot he sheer, with application of the outer sheer clamps and then putting trim on top of the sheer clamps with ash wood. Getting closer to launch day. Haven't decided on paint colors for the outside yet but inside of boat will be kept bright, meaning varnished to show the beauty of the natural wood.