Visit our Popular Forums

**weavis** · 12-11-2016, 10:51

Over the years I have had a lot of GRP boats.
They were of older design and manufacture and solidly built, one inch thick in some places.
Im still in touch with 2 owners who bought them from me in the 80s and early 90s and the boats are still in good order and going strong.

Of late, A lot of my friends with GRP vessels are having work done on the hulls for osmosis, from small patches to widespread problems. When I read articles it seems that a lot of the production vessels need attention after a few years, and this seems strange to me. A lot of criticism is directed toward wood boats and yet Im not seeing GRP of modern thinness and construction being too much better.

I recently looked at an (approx) 40 year old catamaran with a friend for himself and was impressed with the integrity of the hulls and superstructure. WE also looked at a French vessel at 8 times the price and 15 years old which had been in the yard twice for osmosis control and according to the surveyors report, there was concern about one area.

My real world observation of 'modern' GRP manufacture is that sooner or later, within 10 years or so, attention is going to have to paid to the GRP surface or deeper. It seems to be more prevalent than I thought.

Yes I know, lots of factors involved..but....

Im watching follow the boat, and after a MAJOR refit 2 years ago and extensive work on the hulls... the Oyster is back in again for bubbles in the surface of the hulls.

Im wondering if there is more to having a decent thickness of GRP than once thought and if the thickness helps prevent Osmosis? Either that or the production techniques are shoddy or the materials are not as good as once were.

Thoughts?

https://www.youtube.com/watch?v=ihStxSqLOe4&t=1065s

**a64pilot** · 12-11-2016, 10:56

Its the resins, and some I would believe is layup, but not thickness.

In the US for the last 20+ years houses have been made more and more poorly out of cheaper materials and less of them as well, but the houses keep getting larger and larger.
People don't want quality, they want impressive at the lowest cost.
I believe of course the same is true of boats.
You can get a whole lot "more" boat for less money if it's poorly constructed

Cheechako · 12-11-2016, 11:00

I'm not convinced newer boats have more osmosis issues than older ones. Plenty of each really.
However, I have often wondered if modern "dry layup", using less resin, would be more prone to wicking water into it much better than a resin rich layup.

robert sailor · 12-11-2016, 11:07

Mm I would have thought that modern builds using vinylester resins in the first layer would have cut back on osmosis compared to the polyester resins in the past. That said boats that were built before the oil crisis and the subsequent change in the resin formula seemed to have ar fewer problems.

Cheechako · 12-11-2016, 11:09

In about 1999 I was looking at new boats for purchase. I visited a Wauquiez dealer and they had a chunk of hull material cut from a hull as a sample. It was a new design cored hull that Wauquiez had come up with. The core was a hard plastic foam type of thing. Not like airex foam etc, rather it seemed to be injected between the inner and outer hull and was maybe 1.5" thick total. Any tiny air spaces were not apparent like they are in Airex. It was very solid and hard, but light.
Has anyone ever seen this? I haven't heard of it, or seen it since, and cant find anything about it on the internet. Evidently it didn't work out.

**weavis** · 12-11-2016, 11:13

My experience is that boats built before (a guess at the date) 1990 give or take fare better. GRP is a nice material but Im not liking the real world observations Im seeing..

With the build of Seaworthy lass and Noelex boat, Im taking a more detailed look at Aluminium... seems the only downside is electrolysis and that is easily contained if prepared properly.

Cheechako · 12-11-2016, 11:20

Quote:

Originally Posted by weavis

My experience is that boats built before (a guess at the date) 1990 give or take fare better. GRP is a nice material but Im not liking the real world observations Im seeing..

With the build of Seaworthy lass and Noelex boat, Im taking a more detailed look at Aluminium... seems the only downside is electrolysis and that is easily contained if prepared properly.

Aluminum does have it's issues for sure. Paint, corrosion and stress cracking are a few. The right design, builder etc can help with that. I managed an aluminum boat building shop for a few years. Friends also had a big Alum cutter.

robert sailor · 12-11-2016, 11:22

Aluminum is a great choice for a voyaging boat, if I was younger and had more cruising years in front of me that's the direction I'd be going in. A nice aluminum boat is not the cheap seats so a sailor needs deeper pockets to even consider one but a boat like Nolex is building must be a great experience. Dry, quiet and really tough, much more so than glass makes them a wonderful choice.

**a64pilot** · 12-11-2016, 11:23

All materials have issues, there is no clear cut best, although GRP may be the best for the vast majority of builds.

**weavis** · 12-11-2016, 11:24

Quote:

Originally Posted by Cheechako

Aluminum does have it's issues for sure. Paint, corrosion and stress cracking are a few. The right design, builder etc can help with that. I managed an aluminum boat building shop for a few years. Friends also had a big Alum cutter.

Seaworthy and hubby have been on their present vessel also aluminium, and its an amazing boat, looks good and no issues with the alum. If it but had an extra hull I might have been interested

SV DestinyAscen · 12-11-2016, 11:25

Chopper gun + poly resin + lousy QC on moisture barrier.

I think you can find bad specimens from any builder during the 70-00 and there's survivor bias whereby we find good old boats around and forget the bad ones are not in water anymore.

markwesti · 12-11-2016, 11:28

Our boat was laid up in 79', at the time resin was hard to get and quality was in question .Once every roughly 4 yrs. we go through this , but it's OK I like working in the boat yard .

**weavis** · 12-11-2016, 11:39

Perhaps its a Brit boat build thing... Some of my teen years friends STILL have their 17foot grp fishing dory's and not a bother.
Im on my third Westerly Centaur from the late 70s.... nada.

I dont think its selective memory, but Im getting to the age where having a memory is an issue....

The older Cats from England in the main had little osmosis issues. I can think of one with small spots and that was after a bolt penetration at the side of an unused dock.