How long lasts Fiberglass?

12 Oct.,2022


frp fittings

DanishBagger said:

Let's use the ten-percent example after ten years. Yes, maybe it will only be ten percent, but what happens if you have put another layer on there? If you have it painted, lacquered and so on.

Basically, what I am saying is that one-layer might have, say 10 percent chance after ten years, but how about four layers, plus paint, all of a sudden we might be up to 95 per cent again.

(did I make sense)?

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Nah, I mean, it has nothing to do with making sense, but do you know a single boat manufacturer who gives to a composite hull a 10 year warranty?

That should be good to business…if the hulls would resist that long without needing maintenance.

Most boat manufacturers will give you a two year warranty and some of the top and expensive ones will give you a limited 5 year warranty.

And I believe that those 5 years have to do with the life expectancy of the epoxy barrier coat. After all, the warranty that the manufacturers of the epoxy barrier give is also 5 years. I don’t believe in coincidences, at least when money is involved.

MikeJohns said:

Beware of urban myths .......they abound in the marine industry.

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I am a newcomer to these problems and I have started to be interested when I started to get completely different suggestions about the right way to maintain my hull in good shape (it is a 2002 Bavaria 36). I assumed that they didn’t know what they were talking about because they gave me different answers. I have started searching for myself and I have found that nobody really knows for sure. It’s like a taboo, protecting the myth of the fiberglass boat, the boat that doesn’t need maintenance and lasts forever.

Most boat manufacturers are evasive about it and the most honest ones like ETAP (that have been making composite boats for almost 40 years) say things like this:

Can an ETAP yacht remain in the water during winter or does it have to be stored ashore ? ……
The opinions differ on this matter, even among experts and in the specialized press

There seems to be unanimity about the fact that polyester ships should now and then be stored ashore during winter so that they can “dry out” well. This kind of winter storage should take place in a (preferably heated) shed. “

Is an anti-osmosis treatment recommendable when buying a new ETAP yacht?

As ETAP Yachting uses a high-quality iso-NGA gelcoat and the first laminate layer is exclusively made from roving, the chances of osmosis are almost nil on condition of a correct maintenance. So it is not necessary to have it done with a new yacht. However, we do advise preventive treatment for ships being more than 8 years old, especially when they often stayed in the water in wintertime ….

So, they recommend a preventive treatment after 8 years (epoxy barrier).

What I don’t understand is why they only give a 2 year warranty on the hull.

About the relation between an immersed GRP hull and its life expectancy, read what they say about it at Seasurveys co:

“Simple mathematics suggest that the longer the vessel is in water the more water it will absorb the higher the risk. By simply laying the vessel up ashore each season can possibly effectively double the number of years before any osmosis effects are present.”


Re: EPOXY life expectancy.

Since 1988 , a vessl we were involved with, has been imersed
in sea water.
It started out at 65'. Recently it was extended. A survey was required
and the surveyor reported "..... that inside, below,she's as dry as a bone.

One needs to consider: LIGHT destroys plastics. Not just sea water.
There's a lot of things - in process here.

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About the sun, I believe you are right, even if I have not seen hard data about it (regarding boats). That’s why I consider that the best way is having the boat in the water and be sure that the epoxy barrier is in good shape.

In this case I believe that it will be better to be over cautious about it than having any chance to have a high level of moisture in the composite. After all the price of having a new epoxy barrier in the hull each 5 years in not relevant compared with the value of the boat or the problems it can minimize.

This is always the crux with GRP it absorbs water and that water will always eventually destroy the resin through hydrolysis. By using water resistant resins you buy more time but no more than that