sharris wrote:An extra layer of fiberglass on the bottom will probably do a far better job of stiffening the build than adding braces. Or you could use thicker cloth.
I've fabricated a lot of fiberglass items, boats included, and can tell you it's not true. In general, all another/thicker layer of fiberglass will do is make the boat heavier and more costly.
A layer of 'glass is very flexible; it will add little in the way of stiffness. On a per-ounce basis, properly-designed braces will stiffen a structure considerably more than adding more 'glass. Ounce-for-ounce, wood is 10X stiffer than 'glass.
More fiberglass WILL make the boat stronger (tensile and compressive) and add puncture- and wear-resistance, but it will not increase stiffness in an effective manner; there are much better ways.