Old grp yachts

[Keith 66]

When Grp initially sets it is quite flexible (or green) & a new moulding will be quite floppy for some days, the prime example of this was Contessa 32's where they were molded so quickly & placed in ill fitting cradles that many had large dents in their hulls that later had to be filled!
Over a few days to a week the laminate cures to full strength & this may be accelerated with post curing in heated environments. The grp will continue to cure for some time but as it ages will get more brittle. Lightweight laminates such as dinghies will fatigue & get micro fractures wich will cause them to go soft with age. Very old thick laminates will get more & more brittle with old age. Having seen many old yachts & boats damaged over the years its quite noticeable.

 

[Daydream believer]

Apologies for obviously having upset you and your yellow faced friend so much.

Did we need that last bit?

 

[PCUK]

Interesting, haven't heard that before, not desirable I suppose and I wonder after how long peak brittleness is achieved. I don't think it would put me off buying an older FG boat, if for no other reason than they're the only ones I can afford to buy...

When I first went to see my 1969 Bowman 26 I couldn't believe how good the hull was, not a single hint of anything amiss anywhere, had been treated with gelshield at some time though...

To OP, get your ball pein hammer out and make like a surveyor, if it doesn't shatter before your very eyes you should be good to go...

We've never heard that either and we specialise in very old GRP boats.

 

[doug748]

We've never heard that either and we specialise in very old GRP boats.

Nor me, there seems to be a number of inventive posts on this thread

Going to look at an old 1966 grp yacht called an Amel Supermistral 24 any info that can help me assess the hull condition. I imagine is pre core material just thick glassfibre

The general consensus AFAIK is that if an old, solid, GRP hull looks ok, it probably is. Any unbroken blistering tends to be cosmetic but will put prospective future buyers off so needs to be noted against the asking price. There is no guarantee that a relatively damp hull will develop blisters or that a relatively dry hull will stay blister free. Sometimes blistering stays stable for decades or gets slowly worse but, apart from things like lightly built speedboats there is no real evidence of boats being scrapped because of overall GRP weakness.

I know you are looking at another boat now. Cored structures are a different kettle of fish, they are stiff and strong as long as the bonds stay tight. Delamination of internal cores needs to be taken seriously, here is a good example of one with problems:

That surveyor looks good at his work and turns a nice phrase:

" When you own a boat like that you make the most of it.......................when you don't own a boat like that, you try not to " sic

.

 

[Wansworth]

Nor me, there seems to be a number of inventive posts on this thread





The general consensus AFAIK is that if an old, solid, GRP hull looks ok, it probably is. Any unbroken blistering tends to be cosmetic but will put prospective future buyers off so needs to be noted against the asking price. There is no guarantee that a relatively damp hull will develop blisters or that a relatively dry hull will stay blister free. Sometimes blistering stays stable for decades or gets slowly worse but, apart from things like lightly built speedboats there is no real evidence of boats being scrapped because of overall GRP weakness.

I know you are looking at another boat now. Cored structures are a different kettle of fish, they are stiff and strong as long as the bonds stay tight. Delamination of internal cores needs to be taken seriously, here is a good example of one with problems:

That surveyor looks good at his work and turns a nice phrase:

" When you own a boat like that you make the most of it.......................when you don't own a boat like that, you try not to " sic

.

Thanks another boat Iam gong to see Monday could well have a cored deck

 

[Supertramp]

Old to new is not a straight line evolution with decreasing fibreglass thickness. Materials technology of composite materials has developed rapidly and allows hull shapes with flatter surfaces and strategically placed strengthening (metal, carbon fibre, foam etc). It would be very surprising if any material and structure didn't change or deteriorate over time and UV/water exposure. Time will tell whether new builds last as long as old - I don't think I want to bet either way on it! The real question is whether you have confidence in your boat and its structure for the way you use it. And for that you can only consider the provenance and perceived quality of materials and build plus the evidence of surveys and inspection.

My deck is 32 years old and is cored (balsa end grain and plywood). It is a reassuring inch thick even in non load bearing areas. The hull is solid GRP and well reinforced with stringers. I lose no sleep over whether its gradually getting brittle or weaker, at least until the day I decide to sail the NW passage... Far more worries over 30 year old wiring, plumbing and ancillaries.