[Rhodes22-list] Hull strengthening

[James Nichols]

Graham,

Our boat is a '71 model.  The hull liner runs from bow to just before the stern and was what formed pretty much all the structures inside the boat. The only exception was the main cabin floor which was kind of a triangular tub in the middle of the boat.

The blocks I pulled out of my boat simply looked like recycled shipping foam.  My plan is to go back with some foam, but not as much as was there previously.  I would like to recover most of that area for storage.

My plan for the foam replacement is the 1/2" sheets that Home Depot and Lowes sell of high density foam insulation can be cut into strips and line the hull. I plan on shoving it up under the hull liner as well to get foam where there wasn't previously any.  When I lay in the framework for the new v-berth, I'll add in the foam afterwards and then sheet over it with 1/4" ply to provide a durable surface to push all those things we want when cruising for the week.  My retired father-in-law plans on cruising Puget Sound and beyond when we finish so we want as much storage space as we can get.

By my calculations, I'll be using about 3 sheets of the foam which will get me 4 cubic feet of foam lining the boat.  The foam weighs about 1.5 lbs per cubic foot and water weighs a little over 62 lbs per cubic foot, so I'll gain about 240 lbs of positive flotation in the cabin area, and I haven't disturbed the positive floatation under the cockpit yet.

I'm thinking I'll leave that area alone.  The wood for the bulk head going back that way only has a little mold growth on it and is fairly solid still. The difficulty of removing the wood bulkhead and figuring out a method of utilizing that area would be extremely difficult.  I can most likely just kill the mold with a fungicide and finish drying it out so that it doesn't continue to rot. The more I think about it the more I like the idea of leaving it along.

As for strengthening the hull by adding more glass to the interior, on the interior of my hull, the weave is very apparent so roughing up the surface would be difficult unless I sanded the weave smooth to be sure I had abraded all surfaces.  Doing this would remove a lot of material, at least 1/8", from the hull.  My opinion is the hull would be better off left undisturbed.  As you suspect, attaching the bulkheads and other interior components that you plan to go back with to the hull thoroughly will help with stiffening the hull.    James