by Don Snell
After making those shapely high aspect dagger boards Stan described above it is important to modify the trunk to reduce water turbulence and provide a guided fit. The smaller dagger board described above should be fitted towards the back of the stock dagger board trunk.
Inserting a strip of made to fit blue stryrofoam into the trunk will provide a guide for your new boards. This styrofoam will also provide backing to build a partial cover out of wood or fiberglass on the deck. Accomplishing a good fit on the bottom of the hull will require inverting the boat on some saw horses so that the dagger board can be fitted into the trunk. Some tape should be wound around the dagger board in the area where it exits the bottom of the hull. Pack the area between the dagger board and the trunk with some crushed up newspaper about 1/2 inch below the top of the inverted hull between the dagger board trunk and the inserted dagger board. The wadded up packed in place newspaper will provide backing for a batch of two part putty you have mixed up and will place in the void between the hull/dagger board trunk and the dagger board with the tape wrapped around it. Before hand prep the inside of the dagger board trunk by sanding and cleaning the area where the putty will contact the inside of the trunk and hull area.
After packing this void with the putty and before it sets up make sure you move the dagger boards a little bit to make a small void around the dagger board so that it can be removed before the putty has entirely set up or the boards will remain permanently in place! After the putty has set up sand and work the area with more putty if needed to accomplish a good fit for the dagger board. This really cleans up the under side of the hull when sailing. Suitable putty can be bondo or a glass fiber reinforced putty. It can be epoxy or polyester resin based if you choose. There are pictures on the tech photo pages to study.