Dave, perhaps others can offer ideas on the hull work, but to find leaks, try running a air line (low pressure..5-10 lbs. leave it lose not air tight !into the drain plug. then spray soapy water all over the hull..(dagger board wells too) you will likley find your leaks ! mine foam like scrubbin bubbles..lol mark the area with a soft lead pencil. "Get'er done mate"