Checking for leaks
Dave's idea might work. But unfortunately the column of water in a plugged trunk doesn't generate near the force 3000 and some pounds of displacement does. I'd recommned laying paper towel around or marking around the base of the dagger board trunk with washable markers, just before launching. The paper will wet out, or marker lines will streak where the water contacts first, indicating where the leak may be. If the daggerboard trunk is truly fractured down its length (doubt it) rather than where it meets the hull or the leak is coming from somewhere else (more likely), here's what I would do: 1. Sand down the insides of the trunk. (A sanding block on a swivel pole should work.) 2. Apply a thin coat of thickened epoxy to the walls. 3. Let cure and then try the leak detection trick in the water again.
