Has anyone tried just using a single layer of 9 or 10 ounce cloth for the deck, instead of 2 x 4 oz or 2 x 6 oz?
I’m curious to try this method myself, but I would appreciate some feedback first.
multiple layers of glass will hold more resin than a single layer of heavier weight glass. the end result is just a little heavier, but a bit more ding-resistant. in the grand scheme of things, it really doesn’t matter much.
Actually, I think it does.
For sure, two 4oz is stronger than single 8oz.
Weave shows bare glass in heavy cloth, single layer is thinner, losing out on 3D effect.
I’d say two 4oz is stronger than single 10 even.
But maybe against single 12oz, other factors come into play.
You never want big gaps in the glass showing bare resin, for obvious reasons.
i figured the hotcoat and glosscoat would mitigate to some degree and ding resistance from the extra resin in a double-layered lam(unreinforced resin outside the lam). will that extra bit of resin in the lam between the two layers of glass is really going to make that much difference in the strength of the finished product?
I’d think basic, un clothed resin is the weakest structure right where you want strength.
Assuming hot and gloss is on both structures, just the thickness gain of two layers is a plus over single thicker layer.
And assuming full saturation is attained, double 4 closes the bare resin structure with glass impregged with resin, a stronger material.
You see lots of 12-24 oz cloth used with boat building, but they are trying to achieve maximum sheer bulk sizing. They also use woven rovens.
But lately, some companies making small fishing boats are using surfboard building technologies, and are much much lighter while retaining durability…adding cost, but selling more units.
yeah, poly resin shatters so easily. i suppose that with multiple layers, the extra resin is held together between the layers of glass so it won’t crack so easily.
i’ve used only single layers for years.
i don’t cheat on the resin, and i’ve had good results,with some dimpling and depression of the foam, but no delams. used clark blanks ranging from ultra light to classic weight foam. poly resin.
on the other hand, i had some boards i shaped that were glassed by a friend that had previously worked at a local boardmaker reknown for their fragile boards. these boards all delammed. another board was glassed at a local shop, with multiple layers of volan. it’s delammed also. i think that being too cost effective with the resin is really a factor in this sort of board damage.
i found that the weave showed thru on the heavier cloth used, like 8.5 volan, in the lam coat, but pretty much had disappeared by gloss and polish.
i don’t doubt that several layers of lighter glass is stronger than 1 layer of heavier, tho. but here on the east coast, i don’t see that many board busting waves. 1 layer is easier for me…and cheaper.
My thoughts are slightly tainted by the reasoning that from boards 80 on, I finished the glassing with a normal hotcoat.
So tighter weave tends to show less than heavier cloths, skipping the sanding and gloss.
I agree with LeeDD, two layers of a lighter cloth will always be stronger than a single due to the gaps in the weave. These gaps are eliminated by the overlap of the two layers so you get a very dense skin. I’ve fixed my share of dings and have seen rail hits on double 8oz which only shattered the hotcoat. Unfortunately, the foam behind it gets dented in and you wind up grinding the whole thing out like it was single 4oz anyhow. Multiple layers on the deck will give more dent resistance than a single, since these are a slower pressure-related forces rather than sharp impacts like on rails.
I think in theory 2 thin layers would be stronger, but I think as the layers are so thin in either case that the strength difference would be minimal I have been using an 8.5oz satin weave for the last 5 years (with epoxy) with no problems. I did once use a 9 oz uni directional with 84% of fibres running one way (nose to tail) and the rail buckled a bit after 1 year.