Polyester versus Vinylester

[Normanby]

A knowledgeable Geezer at my yacht club was explaining to me that late 70's GRP boats should be avoided because the oil crisis meant corners were cut in making of the polyester resins.

He reckoned that it wasn't until the 80's that manufacturers got the hang of vinylester and rectified the process.

He reckoned that was why late 70's boats are more prone to osmosis.

Does this ring true?

I ask because I'm in the market for a particular make of boat, and they were manufactured between 1966 and 1986, and want to know if I should steer clear of the late 70's ones.

Interested in hearing from other knowledgeable Geezers...

[zeehag]

my formosa is 1976. is solid, unlike many other makes of boat, and is good in high winds, unlike many newer models i see all over the place,mainly in slips in marinas and abandoned.....
my ericson is 1979. fine boat.
there are many bad rumors of all makes of boat these rumors made by dissatisfied customers who EXPECTED something other than what they got.
is a good idea to try out everything. there are resins for all boats and there are ways to properly repair all boats. resin is irrelevant. lay up is not irrelevant. chopper gun layup is to be avoided. all my boats were chosen by the method in which they were laid up--by HAND, with roving and some mat...not chopper-gun and not cored hull. research the marque you like best and go from there.

[Normanby]

Ahh, good tips, thanks.

I'll find out how the Clansman 30's were laid.

BTW, what's a chopper gun?

[zeehag]

chopper-gun layup was shredded mat-looking stuff shot out of a mechanism that would send the junk into the mold to shape a thin skinned and weak hull. clipper marine did this layup technique, as did some other builders of inexpensive boats. was a practice done in usa. i dont know if any other nations had this problem....i know it was done in usa for a few years.

[skipmac]

Originally Posted by Normanby

BTW, what's a chopper gun?

Kind of like a fancy version of a paint spray gun. There is a feed of fiberglass rope from a reel to a blade that chops the rope into short pieces. These are blown out of the gun with resin mixing together onto the mold.

Quick and dirty way to make a hull thicker and not a terrible thing to do in the right place. It is a cheap way to build up thickness in a fiberglass structure but not nearly as strong as hand laid glass cloth. Also tends to leave voids and not always gives a good resin/glass ration.

Layers of chopped strand used close to the gel coat can give channels and voids for water to gather and promote or accelerate osmosis and formation of blisters.

[minaret]

The majority of manufacterers still use a chopper gun, particularly in Europe. It's very difficult to find a boat built entirely by hand with zero chop. These days you are much more likely to find boats built in a bag when looking at boats with no chop. There definitely were serious resin problems around the time of the OPEC crisis. Most of these problems have been well documented.

[denverd0n]

The main thing to remember at this point is that any boat that was built in the 70s (or 80s, or 90s, for that matter) that isn't already suffering from blistering, probably isn't going to. And the ones that have suffered from blistering have mostly already had repairs done.

Don't worry about what was done in a general sense during this decade or that one. Take a look at the specific boat that you're interested in and see how it stands. That's all that matters.

[goboatingnow]

Originally Posted by minaret

The majority of manufacterers still use a chopper gun, particularly in Europe. It's very difficult to find a boat built entirely by hand with zero chop. These days you are much more likely to find boats built in a bag when looking at boats with no chop. There definitely were serious resin problems around the time of the OPEC crisis. Most of these problems have been well documented.

where in the name of god do you get your information, VOC regulations have virtually ended it . Hanse uses expoy , Beneteau et all are switching to close moulds.

I hear its USA boats built in china/Taiwan that did all that crap. ( newspaper as filling etc)

Dave

[zeehag]

rumors are merely that--rumors.

one would be surprised where chopper gun is still in use. corvette cars....etc...

however, that slam on taiwanese boats is just uncalled for. work out of taiwan has been better than the rumors, so back that crap up with pix. i can back up the steel arguments, i have a taiwanese boat. but do not bash my solid hull...is roving and mat and resin, just like other marques, and far better than some i have crawled thru.

there is nothing wrong with the hulls of the taiwanese boats that have been repeatedly slammed.
very solid and stout boats come from taiwan. behave.

[goboatingnow]

Originally Posted by zeehag

rumors are merely that--rumors.

one would be surprised where chopper gun is still in use. corvette cars....etc...

however, that slam on taiwanese boats is just uncalled for. work out of taiwan has been better than the rumors, so back that crap up with pix. i can back up the steel arguments, i have a taiwanese boat. but do not bash my solid hull...is roving and mat and resin, just like other marques, and far better than some i have crawled thru.

there is nothing wrong with the hulls of the taiwanese boats that have bben repeatedly slammed.
very solid and stout boats come from taiwan. behave.

I was actually being facetious actually

dave

[zeehag]

ok...

deck and masts and such i dont mind--is part of the leaky teaky thang--but the hull---only part that doesnt leak on these ...

[Crayfish]

Originally Posted by goboatingnow

where in the name of god do you get your information, VOC regulations have virtually ended it . Hanse uses expoy , Beneteau et all are switching to close moulds.

I hear its USA boats built in china/Taiwan that did all that crap. ( newspaper as filling etc)

Dave

Hanse uses Epoxy? Haha, that's a perfect commercial stunt, I'm afraid.
They use isophatalic gelcoat, the first layer is vinylester, the rest is cheapest orthophtalic resin.

Crayfish

[minaret]

Originally Posted by Crayfish

Hanse uses Epoxy? Haha, that's a perfect commercial stunt, I'm afraid.
They use isophatalic gelcoat, the first layer is vinylester, the rest is cheapest orthophtalic resin.

Crayfish

This is still the most common construction method everywhere, I'm afraid. Anyone who's ever built a boat in a factory can tell you why the chopper gun is still in use, it is a massive time saver for the builder. I use a Magnum myself. Quality really counts when it comes to chopper set ups. I've tried to explain how external mix guns contribute to the problems we see in hull lams before. I'm not sure people get how this works.

[noelex 77]

Originally Posted by Crayfish

Hanse uses Epoxy? Haha, that's a perfect commercial stunt, I'm afraid.
They use isophatalic gelcoat, the first layer is vinylester, the rest is cheapest orthophtalic resin.

Crayfish

Hanse have an epoxy option, for most hulls.

The layup you have described contains no epoxy at all.
I don't think even a good marketing department can stretch the truth, for the optional epoxy option, that far

[Sand crab]

Minaret is correct about the chopper guns. I've seen boat building vids with them using it. Most of the big builders are doing it and the small ones as well. Mono and multi. I'll try to find one.