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Old 11-03-2011, 03:38   #1
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Old Fiberglass Boats

Hi all,

I am new to posting on the forums.

I am sure this will of been discussed before, having done a search I could not see anything.

Presently I have a 24 foot sailing boat built late sixties. Built very heavily, she is not worth allot so I have self surveyed her. As a surveyor would of cost as much as the boat!

I am happy with her, the sailing she had done she owes me no favours She is just getting a bit small for extended sailing, weeks not days.

I have my eye on a bigger boat of similar age.

I understand the dangers of osmosis, keep it under control and you should be fine. Seems to be the advice.

What other dangers are there as fibreglass gets old?

Does it become significantly weaker?

I know some boats have known issues keel bolts, mast steps sinking, balsa cores weakening.

I figure these can normally be dealt with with work or cost.

But do fibreglass hulls, significantly weaken with age?

Unlike wooden boats you cannot replace planks, double ribs etc.

Any advise or links to articles would be appreciated.



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Old 11-03-2011, 04:45   #2
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Re: Old fibre glass boats.

The glass itself does not seem to deteriorate with age, more concern as you mention, with any areas that have a core inside the glass usually plywood, balsa, foam. Decks frequently have a plywood core with fiberglass skin on both sides. Check any places where fittings are mounted or any sort of hole drilled to make sure they are properly bedded and sealed. Obviously wet wood sealed inside fiberglass can be a problem.

The other area of possible concern is where things like bulkheads and floors attach to the fiberglass hull. Over time they can come loose if not well attached originally or if a wood bulkhead gets wet and the bond of the glass to the wood is compromised.

Otherwise any area that might bend or work I would check but in a well built boat that should not be an issue. Especially older glass boats they tended to use more glass which reduces that concern.

If an external lead keel I would check around the bolts if the keel has worked at all and also the joint between the keel and the hull.

Those are the main areas I would check first. Feel free to ask further details.


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Old 12-03-2011, 18:59   #3
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Re: Old Fiberglass Boats

I have seen fiberglass boats from 60'ies and they were in great condition. Very much depends on design and then on maintenance.

I am not certain how long a fiberglass boat will last, but I have not seen any one disintegrate other than due to poor design or lack of due care.

Where sandwich construction was used I have seen very many cases of failure. This relates quite often to decks and cabin tops as owners tent to attach new equipment wherever without proper routing / epoxying and sealing.

Some designs will have repetitive issues of age that you will find by contacting owners club on-line. This is one of benefits of going for a fairly popular design with large following and an active class club.

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Old 12-03-2011, 20:14   #4
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Re: Old Fiberglass Boats

I don't see any particular reason why a (good) fiberglass hull can't still be sailing 1000+ years after it's built, provided proper care.

The 'proper care' part is probably the kicker. I'd guess that most fiberglass boats die an economic death long before a seaworthiness one. Old sails, decrepit electronics, rusty rigging, then hit it with an engine death, and it's not hard to see a refit cost that far exceeds any conceivable resale value.

Classic wooden boat owners will often spring for refits that bring shame to us plastic owners. You can't expect much sympathy from the woodie owner doing a replanking, when you are faced with a 'mere' recore job that sends your plastic hull to a landfill.
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Old 12-03-2011, 22:07   #5
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Re: Old Fiberglass Boats

Cyclic loading is the death of 'glass structures. Fortunately most old 'glass boats have long since been out of favor in the eye's of the owner, so they don't get used much, hence not a lot of continued laminate "testing".

Yes, 'glass wears out, but this is usually only seen on race boats that have been pushed to the edge of their preformance envelop, for their life span. I've seen laminates that were shot after just 3 years of hard racing circuit use. It's about this time they are replaced anyway, so the laminate engineering was preformed with a well scaled level of need.

As far as old cruisers, well this is a different can of worms. Most are built fairly heavily by comparison, so never really get tweaked to laminate failure points. This is especially true of production craft of the 60's, where they didn't engineer much, they just made the laminate thicker then they thought anyone would truly need.

Usually what kills them, other then catastrophic laminate failures in some structural element, is the gel coat becomes so baddy cracked and crazed that it cost too much to "revive" the old gal, so it's dragged to the land fill.

It also depends much on which make and model you have, as to what will ultimately become of the laminate. Some are so damn thick, they may very well still be around in a melimum, though I would suspect unless substantial in door storage is employed, she'd depolymerize before this.

In the end it's just like any other building material and subject to the maintenance she's received, life she's seen and the laminate type she was adorned with in the first place.
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