Re: Woven Roving - Good for transom and stringers?
I'm currently redoing the stringers and floor on my boat. The stringers were covered in one layer of woven roving. Judging from how that turned out it isn't a good choice. It was delaminated from wood in spots, at the top of the stringers the fiberglass was all gone, the part that remained was not formed well to the stringers. Several corners raised up and the glass was actually out of the resin and full of holes to let water into the stringers. Maybe it was just poor craftsmanship on the boat but it convinced me that one layer of woven roving isn't going to cut it on stringers.
You are correct in saying one layer of roving won't cut it.
If they only used one layer of roving they obviously did it incorrectly and then compounded it with poor workman ship.
When using polyester, mat should always be used as a first layer, and then between each layer of woven or stitched fabric, otherwise it will be more difficult to work with and be much more likely to fail.
There are a couple of reasons 24oz is used more than 18oz, in fact 18oz is used so little most shops don't have any on hand.
1. It will cost more per lb to make 18oz because the machine needs to do the same amount of work, but less total weight of product is made in the same amount of time. (glass is sold by the pound)
2. You should still use a layer of mat between each layer, so if you use 18oz the layup will be weaker for the same weight, or heavier to achieve the same strength, this also increases the cost.
As far as how easy each product is to work with, it can vary. Glass can be treated (coated) in many different ways and each manufacturer will have many different options for treatments, some can make it stiff and hard to work with, and others can make it soft and limp. The other thing that can affect it is age, sometimes when it gets old it can become very stiff and hard to conform to some shapes. So just because you find one type to be stiff and hard to work with, the next time you buy it it may work differently.
Also many of the retail sellers of glass buy it on price and availability, so just because they carry one brand right now, it can change tomorrow and work totally different.
