mast support

[Ron Skelly]

I am making a prototype for a unique (in my opinion) small sailboat design. I am making the first one out of foam which I will carve and then most likely covered with fiberglass & epoxy.
Question: In this type of scenario I am not sure how to strengthen/support the hole that the mast pole is inserted in to or how I would calculate the strength required. Any ideas in how to beef this up for testing next summer would be appreciated.

[Doug Lord]

You need to provide more information:
1) SA? main + jib? Height of Center of Effort above hull?
2) stayed or unstayed?
3) maximum righting moment?
a. max beam?( on-deck and at the waterline?)
b. crew position(trapeze,hiking?)
c. unballasted dinghy or ballasted keel/centerboard or daggerboard?
d. estimated boat weight?

Good luck with the boat!

[alan white]

Depending on the exact diameter of your mast, and assuming no stays, a socket would probably be the obvious solution. A sched. #40 pvc pipe of the right size could be glassed around to create a socket. If not quite the right diameter at first, start too small and wrap wax paper around the pipe until ideal for a slip fit. Then glass/epoxy and make the pipe for attachment to the hull, pulling out the core after curing.
Add a generous flange on top to adhere to the deck and a poured plug (epoxy/chopped strand) in the hole's bottom to stopper and seal it.
Greater strength could be had by also attaching the pipe to the boat's bottom.
You can drill for the pipe by using a hole saw with an extension. The mast step can then be installed in an epoxy mush (a small hole in the boat's underside will allow excess to escape while you push the step in.

[BATAAN]

Another way to make a male plug to form a laminated mast socket is use styrofoam surfaced with sheet rock mud, sand to a fine finish, wax it, glass it many lams, then dig out the styrofoam.... presto a custom molded part just the right size and strength.