Should I get vinylester resin rather than DCPD?

[jsc7]

I am buying a new boat which is being constructed. Normally the boatyard makes its outer hulls with DCPD which is an isopthalic polyester resin. My concern with this is that guides such as David Pascoe's guides on buying power boats say that isopthalic resins are water permeable and consequently susceptible to blistering. The yard is willing to do the hull in vinylester for an additional cost, but they say they think it is unnecessary because they use an epoxy primer which is water tight and that they have never had a problem with blistering in their boats.

They say that the DCPD gives a better paint finish than the vinylester would.

Should I insist on vinylester, or will DCPD with an epoxy primer be fine?

[robert sailor]

Don't know about power boats especially if they are dry docked A lot but a well built sailboat uses vinylester in at least the first layer and then you can use poly after that.

[Fore and Aft]

I am surprised that the first two layers of glass are not vinylester. I would be insisting on it. Epoxy barrier coats are good but not perfect for long term osmosis protection.
Cheers

[Seabeau]

Perhaps the yard can provide a hull warranty concerning the issue, thru an insurance company.

[El Pinguino]

When my 30yo boat had her osmosis problems sorted by 'Osmosis Solutions' in Gulf Harbour, NZ, in 2015 they used vinylester and gave an 8 year warranty.

I think they know what they are doing... at least I hope so....

[Benz]

If either way they epoxy barrier-coat the hull, then the paint finish depends on the barrier coat, not the resin used underneath. I would pony up for vinylester.

[nortonscove]

Why not ask for access to older boats or their owners. People are usually quite willing to be negative.

[Davidhoy]

They want to use DCPD resin for cosmetic reasons? That alone would give me pause...

-David

[HopCar]

Since you’re building the boat new, I’d pay a little more for the vinylester resin and epoxy barrier coat. Then you don’t have to worry about it.

Note that epoxy primer is not the same thing as epoxy barrier coat. Epoxy primer is not applied thick enough to be completely waterproof. Epoxy primer is just used to allow the bottom paint to adhere better to the gelcoat.

Epoxy Barrier Coats like Interlux 2000 are applied much thicker and have additives that make them more water resistant.

[DocHolliday]

Originally Posted by Fore and Aft

I am surprised that the first two layers of glass are not vinylester. I would be insisting on it. Epoxy barrier coats are good but not perfect for long term osmosis protection.
Cheers

The "first layers" being outside or inside the hull? I tend to think about "first" in terms of inside as a hull is being laid up, but outside here makes sense in terms of water exposure...

[JOHNMARDALL]

Pay for the vinylester - when you come to sell the boat, many years from now and there are no blisters, you'll get your investment back with interest, and then some. Yes, the vinylester will be used in the first chopped strand mat layers of the lamination schedule applied to a female mold.

Good luck
John Mardall
Vetus Maxwell Group

[Sailmonkey]

Originally Posted by DocHolliday

The "first layers" being outside or inside the hull? I tend to think about "first" in terms of inside as a hull is being laid up, but outside here makes sense in terms of water exposure...

Hulls are typically built in female molds, so first comes the gelcoat, followed by the first layer of glass/resin, which will be on the outside.

[fabricator-ken]

go Vinylester given the chance. For sure.

[HankOnthewater]

I agree with everyone who is saying : go with a few layers of vinylester on the outside of the boat (and inside of the female mould).
However I did not see what size and type of boat you are getting. If you get a power boat that is used once a fortnight and spending only a few hours in the water..... no need for vinylester then, same for a trailer-sailer that is only used for a dozen weekends over the summer months.

But,......... when you come to sell, the use if vinylester might differentiate your boat from a dozen others. Your boat will sell first. So make sure you get proof (invoice and/or photos)!

[Mike Banks]

Vinylester. It is as exacting to mix as epoxy--but far superior to polyester.