New to Fiberglass, very basic questions...

[Fanie]

If I work with polyester in hot weather it kicks in 10 mins and in the sun in less than 5 mins, minimum catalist. It seems the UV or IR speeds it up a lot.

I use a slower catalist now, I get up to 30 mins, but when it kicks it goes quickly.

With polyester you have to finish a part as one, you cannot leave it to cure and carry on later. It will delaminate or make a poor bond !

To lengthen your work time (and there never is enough) you can cool the polyester down and work at night when it's coolest.

Mix small enough quantities to use all in a few mins. I suggest you make a few side parts to get the feel for it. A lot counts for proper preperation before you take off.

[Fanie]

Afella,

You cannot allow the layers to cure if you use polyester. The gell coat has to be allowed to kick some, but you cannot leave it to cure then apply the next layer. See manuf specs !

If you do a hull layup, someone with knowledge of the boat hull has to design the layups and the layers used. You cannot dunk a bunch of layers in there and expect it to be correct. The layers have strengths in certain directions, if applied improper you may end up with a twisty hull or not strong enough in some places.

Of course you can make it so thick (and heavy) that no one would care, but that poses a bunch of other problems. There is little way around doing it right.

At least see someone that can design the layer requirements. It will be like nothing compared to the boat's cost and if it's a bugger up it will be huge loss. Don't underestimate this !

There are some pro's here that already gave some advice, I had a quick look and it seems about right to me.

To mention one - CSM IS rubbish. I will either use woven to make up the extra thickness, at least it will add some strength. Really csm is not good. Use it to make flower pots for the garden.

Another one, the ratio for glass to resin is 1:1 if you work carefully and have time to distribute the resin evenly. Usually with hand layup you use more resin than glass, especially when it is hot. There are other methods to build that allow about 50% resin to glass - which is about optimal power to weight ratio. Resin does not contibute to the strength of the layup - only the glass do.

One must remember that while a boat can be made very light weight, the correct way to design a boat would be for worst case conditions. The guy building a canoe can get away being ultra light since he will not use it in stormy weather / water. A sea going boat however has to be able to endure the abuse, at the expense of weight and cost and more work.

If you see a boat that broke (not talking getting smashed on the rocks) or develop other problems is usually a faulty building method / lack of knowledge / skill, /incorrect materials used.

Properly built boats last forever, especially fiberglass boats.

[Fanie]

placing a layer of glass between the foam is not making best use of the reinforcement. All the glass should be only on the outer surfaces, just glue the foam together.

AndrewK made this comment previously. The use of foams I think is greatly misunderstood though important and nessesary imo in all glass boats.

Well it's obvious, fiberglass doesn't float. You don't get into **** then wish you added some foam, you add foam first then get into ****.
A small priority matter

I have yet to see a foam or foam core that contributes to structural strength in a boat. I have various samples and pieces here, and there is no way any of them can count as structure.

The outer layer of the glass is what make the hull's strength, as in the quote. The foam - if also glassed will add to the stiffness. Since the outer and inner layers are parallel only the sheer strength and the panel size in the foam counts here.

If the idea is to use some of the outer layers glass on the inside then you weaken the hull, although it will be stiffer it will break or puncture more easily.

The reasons for using foams is flotation, stiffening of the hull, sound and temperature insulation. If the intent is to stiffen the hull then it is at the cost of extra glass. The rigit foams should be glassed over in any case or it will crush ie when you walk on it or heavy items placed on it.

The softer flexable closed cell foams does not have to be glassed and some can actually withstand a lot of trafic and abuse. The soft foams if not glassed over will not contribute any to stiffness, only flotation and insulation, while pleasant to walk on or come in contact with ie if you lose you balance and bump into it.
Also works very bloody nice to hook your fishing hooks into which for me is a high priority