Originally Posted by Razcar
This sort of thing is a gap in my understanding and thus the source of my inquiry. I see a lot of terms like this that describe the way a hull was built (in halves, in a whole mold, laid by hand, with a core, without a core, etc). It would be nice to see something somewhat comprehensive to describe that evolution. Most boats out there are old, and their builders chose a method of building which, at the time, may have been cutting edge, but over time proved to be terrible, for example. That's what I'd like to learn about.
except for a few lone examples (usually home built) all production glassfibre boats are built in a mold. It is the easiest and fastest way to build a boat. "hand layed" glassfibre is just that.. a gelcoat is sprayed onto the mold (after a release agent that keeps the gelcoat from adhering to the mold) and then a layer of resin is placed over the gelcoat and the woven glass mat is laid into mold by hand. A few layers of this and you have a complete hull, ready to be removed from the mold.
Chopper gunned hulls are started similarly, a release agent, then the gelcoat, then some resin is sprayed onto the mold and then the chopper gun is used. This chops up glass strands into smaller particles and sprays them onto the resin. A few more layers of resin and chopped up glass and you have a hull ready to be popped from the mold.
While handlayed glass sometimes leaves air and resin gaps, it is stronger because the weave of the glass better resists flexing and stretching. The chopped strands of a choppergunned hull do not have the integrity of the glass mat to fall back on.
Many builders use a hybrid. Structural areas will be handlayed glass mat and the rest will be filled in with chopped up glass to build up the hull itself