Problems with ancient GRP?

Salty

Salty

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Does anyone have any experience of problems with old GRP boats apart from osmosis? I mean is there any evidence that the stuff just falls apart after a certain time? I'm thinking of buying a 'classic', but avoiding wood and going for a 1960's fibreglass model (Nicholson 32 for example), but slightly worried about the longevity of a hull that will have been in salt water for more years than I've been around. Any tips, hints welcome.

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My boat is early 1970, no problems with GRP. Have a friend who works at a boat yard who opinion is that it is the more modern boats which suffer most from osmosis as their gel coat is thinner. This is hardly a scientific observation as there are a lot more modern boats around then those from the 60's & 70's.

Regards

John

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our boat is a vancouver 27 which was built in the late 70's. There is little evidence of osmosis and the hull is nearly an inch thick. As far as I have read, older GRP boats, especially ones from good builders (nichoson included) seem to have a good reputation for longevity.

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The Seamaster I moor next to was sold last year. They did not have a hull survey, and I believe the boat to be around 1970. When I saw the new owner later in the year, he said it had been found to have some rot (sorry I forget the name...fibreosis, or something??? probably totally wrong) It was not osmosis, but the hull, had gone 'soggy' as the fibre in the hull had rotted.

I've been reliably informed, by many experienced people, osmosis is not a serious issue. The only real problem comes when it is wrongly used to reduce the value of your boat when you come to sell. All GRP boats have, or will have some osmosis.

From my chats, and reading from the past 2 years, I would say a survey would show up any serious faults in the GRP.

I bow to others with more experience obviously.

<hr width=100% size=1>Malcolm.
<A target="_blank" HREF=http://www.angelfire.com/rnb/malcsworld/>http://www.angelfire.com/rnb/malcsworld/</A>
Take a look at my boating pages.
 
Our Maxi is 1978 built and a good 15ml thick (from where we took out plugs to install the leg fittings.) When she was surveyed she was so dry that the surveyor asked us to ask the owner about storage and where. She had spent about 6 months in a shed in the Caribbean and was absolutely damp free.

My last boat was a 1972 Halcyon 23, with small dampness but nothing serious when I bought her. After shotblasting, filling all holes, regelcoating etc -a long long story and even longer job, but I learnt a lot :) - when we sold her the survey showed her drier than four years earlier.

So I think there are a lot of scare stories, get a good surveyor, and use any evidence of dampness to get the price down.

Sarah

<hr width=100% size=1>Sarah&Pip
 
Where do you get the idea that all grp hulls have osmosis. Just sold a Westerly 33 of 79 vintage and nary a sign.....and the hull below the waterline was about 1.5" thick. Recognised fact..Home Completed yachts never have osmosis, Why? 'cos by the time they go in the water the hull has completely cured, it takes about 9-10 monthts for the GRP to finish curing. Lots of info if you want to look. Older vessels tended to be moulded with GRP hulls to the same thickness that planking would have been.......Petrol crisis in early 80s, and value engineering had a lot to do with the reduction in hull thickness. The thinner the less cost. Tony W

<hr width=100% size=1>Tony W.
 
the fibre in the hull is glass, glass doesnt rot.
stu


<hr width=100% size=1>http://www.beneteau-owners-association.org.uk
 
Exactly, so what has gone rotten?

<hr width=100% size=1>Malcolm.
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Take a look at my boating pages.
 
Rotten GRP.

I've seen 'rotten' GRP where it has lain in damp up against concrete for a number of years, with no gelcoat or paint protection. Not on a boat mind you, and only with a thin layer. The material goes almost straw-like, both in colour and texture, quite soft and sodden, and ultimately will just peel away.
 
possibly not "wetted-out" & rolled sufficiently @ lay-up.
early boats were liad-up very thick/ heavy, compaired to to-day & there is enough "meat" left to repair any defects due to the learning curve of days of the past

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Re: Rotten GRP.

Certain types of conccrete in long term contact with GRP will attack the resins chemically, and cause them to go hard and very brittle. We have a boat in the yard at present which someone had ballasted by pouring a couple of hundredweight of concrete into the bilges. The Resin shatters at a hammer blow rather like a windscreen, as the glass holds it together but the resin shatters.

The glass fibres - being glass -will not rot, but I suspect the problem of 'rotten' glass fibre is in fact the result of wicking. If the glass fibre mat was not wetted through properly at lay up, or humidity etc prevents the resin adhering to the individual glass strands, water will penetrate by capillary action. Polyester resin is not entirely waterproof, so water is being pumped into it along the glass strands, and this can cause all kinds of problems. Not least come the next hard fros, when the expanding ice is much stronger than the surrounding resin. If the resin was already a poor mix, or overloaded with filler powders, then there is very little strength left.

This I suspect to be the cause of the 'rotten' glass fibre we are talking about. The yellow colour reported is caused by the styrene in the resin - sadly familiar to osmosis sufferers as the yellow strong smelling liquid found in the blisters sometimes!

I own a GRP boat laid up in 1959 - the bilges are over 2 inches thick, but even so the builders still built strengthening ribs all the way down as though it was a timber boat. They even carefully moulded lands in to look as though she is clinker, with a view to further stregthening! Massively solid, very heavy, therefore a bit slow, but the mouldings are as good as the day they came off the moulds. Couldnt say the same for the various fastenings, keel bolts etc, all now replaced!

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Thanks for your replies. I'm sure this knowledge may help Robert (Salty) and others when buying older boats.

<hr width=100% size=1>Malcolm.
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Take a look at my boating pages.
 
I have a 1963 Elizabethan 29. She got osmosis and was epoxied in 1989. One problem with old grp boats is that the lay-up techniques were poor, if not experimental. Mine had loads of little voids between the gelcoat and the glass, and water got in, and wicked down the glass. Great chunks had to be ground out and made good. The hull is still a bit damp today, but I put that down to rainwater in the bilges.

The good thing about old grp boats is they were built like brick outhouses by today's standards. I was shocked the first time I went on a modern boat at Earl's Court and realised you could see light coming through the topsides. I have at least 10-15mm all over, and the main structure is supported by hardwood: stem, a substantial deadood, stringers, beam shelf, king-planks for the fore and aft decks; as well as two structural plywood bulkheads, with steel reinforcers, under the mast step. It's as if they didn't trust the structural strength of grp, and half of her was built using wooden boat techniques.

Many old Lizzies are still going, including No.1 and No. 2. I don't think grp lasts forever, but 40 years so far bodes well for the future.


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My boat was built in 1979 and the GRP is pretty thick. The boat is in commission all year round, just coming out for a lick of anti foul in the spring. No sign of any Osmosis or any other probalmes with the GRP.

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G'day Robert,

Fibreglass must have a half life of 10,000 years, we don't know for sure; water ingress and chemical attack will reduce its life span, but I suspect not by much.

I am at the moment removing a fibreglass covering on balcony that laid over timber 40 odd years ago, the only reason it has to be removed is because the original layer did not far enough over the outside edge, as a result, water has rotted the timber. I ground into sections to see how well it was put together back then, a bit on the dry side when it came to rolling in the resin, but still very flexible and durable. All the time the only protection it had was a coat of paving paint.

I have also repaired, modified and trated many older boats for high moisture (not all blisters are Osmosis) and have every confidence the older hulls. As stated above its some of the newer ones that suffer. One thing to bear in mind though, resin was in short supply in 64 I think due to an oil crisis, the resin manufacturers cranked up the extraction process to get as much as possible, this, we found out later, was not a good drop, and many boats built just after oil supply problems later suffered. I believe this problem has now been solved with much improved quality control measures.

See and old GRP boat from a reputable builder, get a survey, get a good solid boat will outlast you and your children.

And Avagoodweekend........

<hr width=100% size=1> Old Salt Oz /forums/images/icons/cool.gif Growing old is unavoidable. However, growing up is still optional.
 
Re: Old not always good

> As far as I have read, older GRP boats, especially ones from good builders
> (Nicholson included) seem to have a good reputation for longevity.

The longevity might come from a heavy build but Nicholsons and Contessas have a noticeably troubled osmosis history. Vancouvers can get osmosis as well, there was an example sitting on the market at Hamble Point for a year with early stage osmosis.

Beyond early preventative epoxy treatment I think a regular annual haul-out schedule is the most significant osmosis prevention factor.

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Ours is a 1972 boat and I'd echo the comments of other owners of older GRP boats - about 3/4" thick hull layup in most places and EVEN THICKER where they thought they might need more strength! I think I could probably cut out all the internal stiffeners and it wouldn't make a difference!

This year I've scraped the antifouling back to the epoxy applied by the previous owner. It looks like he made an appalling job of it but the hull is none the worse - no blisters or signs of delamination.

The topsides, however, are a different story. Both sides (but mainly port) are extensively crazed and there are also a number of tiny pinholes (literally less than 0.5mm across) with fine cracks radiating out from them. I've been told it's nothing serious - just cosmetic and that there comes a time in every GRP boat's life when you have to resign yourself to painting the topsides. I'm not sure the latter is true (if well gel-coated and maintained) but an annual attack with a buffer has so far rendered them almost invisible (from more than about 10 feet away) for the best part of a season. Also, pigmented gel-coats on older vessels (particularly in sunnier climates) often loose their shine and sometimes the colour fades. Red is particularly bad as it goes a sort of Terracota colour. Darker colours (especially dark blues) are much better. Mostly, these can be restored with a good buffing but in extreme cases you might need to abrade with fine wet-or-dry paper first. Obviously, there is a finite number of times you can do this!

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