This is a good time to think about drainage inside your hull. When the hull is in its correct position, there will be low points on the stringers. Careful observation will enable you to locate them at this stage. This is the area where moisture can collect inside the hull and cause rust.

   If you’re intending to install foam insulation, especially the sprayed-in variety, you won’t have this problem because the foam should come at least to the inner edge of the stringers. The foam will provide a flush surface and leave nowhere for moisture to collect. In foam-insulated boats, any condensation that does occur will drain into the bilge. As your boat will need insulation, this is the obvious answer to a known problem.

If you’re going to install preformed insulation, instead of the sprayed-in variety, you may wish to grind small semicircular holes in the low point of the stringers. Arrange them so they leave a drain hole between the stringer and the hull plating.

   Some frames, too, will require limber (drainage) holes, but there’s no point in cutting limber holes in the areas of the frame or keel webs where the hole will be later filled with ballast. The forward and the aft frames will need limber holes to allow water to flow to the lowest point. Check our plans and give some thought to this drainage situation.