Fruits Of My Labor (A-113)

[ebb]

You do nice work there, buddy.

What I like especially is the tabbing you did on the bulkhead to get that beautyful line! It takes time to make patterns. It takes time to do it right.

Very impressed!!! Happy boat!!!

That beam is a real sunbeam!

[ from Fiberglass Boats by Hugo du Plessis (Adlard Coles, 1966)
Pg 57 in the section titled, "Hard Spots and Stress Concentrations:

"Many hard spots do not appear until several months after the boat has been moulded, not until the moulding has cured, contracted and settled down. Some moulders would probably be surprised to see how noticeable the hard spots have become six months later, and there is no doubt that some, particularly the hard spots associated with bulkheads, are due to contraction during cure.
Most stress concentrations will give no trouble in normal service because a good design will have an adequate factor of safety. But these hard spots are in fact eating into the factor of safety, so that when the overload comes, an impact or a sudden squall, the factor of safety is not there. The moulding will fail, whereas one without hard spots would not,
1. Round off all sharp corners...
2. Broaden and taper off the root of all bulkheads and shelves. Keep bulkheads and incompressible members from direct contact with the skin, so that the strain is taken on the broad-based angle fillets, or use a soft padding between the bulkhead and the hull.
3. End one structural member at another, or fade it into the skin...
4. Make all changes in thickness gradually....
5. Radius all corners...
6. Bolt or fasten all stressed fittings through blocks....
7. Make or pad fittings or woodwork to fit...

Distribute all loading and stress.
Visuallize how the moulding will deflect.
How can any stress concentrations be avoided."

Tho we go to him for his experience, the trouble, as we know, with any expert is that we have his predjudices or opinions to weed thru, as well as the heat level of his persuasion. His saying that the skin will fail at a point load (the boat twisting probably in "a sudden squall") is unsupported by any examples or fotos. Not to say that I doubt it. However, what you are doing IS substantiated by the guy who IMCO wrote the first (and best) manual on the subject.]