Re: Advantages of Vinylester resin?
The quote above explains it pretty well. Many boats today use VE blends as skin coats or barrier coats on the hulls to help protect against blisters, not too many use straight VE, most are VE DCPD blends.
I frequently see the "not water proof" comment made about polyester resin, there are inexpensive resins that do not hold up as well during constant emersion as others, but I don't think you could say it's not water proof. The same thing can be said about epoxy, there are very good epoxies and there are less expensive ones that aren't nearly as strong or water resistant. You get what you pay for in all three products.
For deck replacment, very little advantage, if you mean floor, then maybe some, I don't thiink it would be worth the cost for most boats though.
Stringers, again a little better bond and a tougher resin, but it would be hard to tell the difference.
Transom, for a high performance boat it can help, but on a small boat with a medium or small OB just use polyester.
Cosmetics, typically poor, straight VEs don't cure as well at room temperature, that's one reason why most boat builders use a blended VE. There are some Straight VEs formulated for good cosmetics though.
If you are making a high performance boat, or repairing one, then the added strengh of VE resin can be used by an engineer to design the boat to be lighter and stronger.
If you are replacing a transom or stringer because the wood rotted away and you replace it with the same or similar laminate, then you didn't gain anything. The polyester resin didn't fail, it was strong enough to do the job, if you use a better more expensive resin (epoxy or VE), all you did was spend more money than you needed to.
The problem with buying resin (and some epoxy) is that you don't really know what you are getting. Resin companies don't sell to the retail market, they sell drums to to companies that repackage it into smaller amounts and sell it to you, so most of the time you never know who made it, or exactly what type of resin it is. Many of these companies just get resin from the cheapest source and it may change from month to month. The same goes for epoxy, only there are some brands that do sell to the retail market and have very good products. Others just get a lower grade epoxy with an attractive price and little or no help or information, they just rely on the "epoxy is great" line of thought and most retail customers don't know enough about epoxy to ask many questions about it.
One good thing about polyester resin, is that what you can buy over the counter is normally better than what is used to build most boats. The resin used to make boats in a factory can have a very short shelf life, not something you want in a resin that may sit on the store shelf for months before being used. The more stable (longer shelf life) resins are typically better in quality.
