How long lasts Fiberglass?

Hum, Good old fiberglass boats! One of the problems nowadays is to know what the hell is a “modern” boat made of?
With so many “advanced” building techniques and materials, it is very difficult to know what you are buying, and almost impossible to compare the resistance, longevity, stress resistance and impact resistance of two different boats built with different materials and technologies.

Take a look at this article written by a largely experienced surveyor:

"Not long ago I was the recipient of a rather distressing revelation……

Or, to put it another way, these boats got broken up by only a few heavy impacts, and not hours worth of sustained battering. In several of my articles on the subject of construction, I have a photo of a 42 Bertram that broke loose during Opal (1995, Florida panhandle) and was badly battered against pilings and other objects for many hours. The hull laminates did not fail, but obviously had sustained a horrendous beating. I used those photos as a good example of just how strong an ordinary fiberglass laminate can be…….

What was so eye-catching about these boats is that many of the broken up pieces did not show any significant degree of heavy battering. The analogy here looked more like hitting a glass bottle with a hammer -- it only takes one swing to break it…….

Thirdly, what next caught my attention, and what I found truly distressing, was that these damaged boats revealed what they were made of. Simply put, whatever these materials are, I didn't recognize many of them……

But now we have something new entering the scene, something they call "advanced composites." A composite refers basically to two or more materials that are bonded together. If you glued a piece of wood and plastic together, technically that would be a composite. A balsa cored deck is also a composite, though most of us would just as soon call it cored construction because we know what that means. When the marketing people say "advanced composites," well, we don't know what that means since it could be anything, which, judging by what I saw and the photos displayed here, it does mean just about anything……

The first question to cross my mind was, "Can these fairly be called fiberglass boats any more?" What we see here are hulls made with increasingly less and less fiberglass, and more and more of something else. Some of these boats were stunning in the limited amout of structural fibers used………….

What we see here really begs the question, for glass fibers make up only a small percentage of the total laminate thickness, which, as you can see, is pitifully thin to begin with. How about a hull side on a 27 footer that is 3/16" thick, with 2/16" of it being this putty material? That means there was only 1/8" of glass that included the gel coat. Could this leave any doubt about why so many of these small boats got busted to pieces in a minor storm, in a place where there was almost no storm surge? Not in my mind, anyway………………………..

These examples were not confined to just a few boats, but covered a fairly wide range of builders. And most significantly, of the boats which were built with solid fiberglass construction, I did not find one that was busted up anywhere near like these "advanced composites." Not one. There were some old Bayliners and Mainships (1970's) that were badly battered, but none were broken up. A few cracks maybe, but mostly heavy gouging and battering……………………….

One conclusion we can certainly come to is that the strength and impact resistance of boats built with these materials is something worse than merely inadequate. In the past, it was generally true that no matter how low cost the boat, a decently laid up solid laminate hull was capable of surviving a heavy beating without the hull breaking into pieces as we see here. As near as I can tell, the boats shown here received a minor beating, and broke to pieces. How can there be any doubt of that when the major part of the laminate is nothing but putty?...........

It has always been the case that when a surveyor calls a boat "fiberglass," he's making an assumption -- an article of faith based on the fact that there were no other materials being used other than standard balsa or foam cores. Now we have a new paradigm. Enter a whole host of new materials, of which no one knows anything about, but for which we are getting some pretty good indications that many of them leave a lot to be desired."

http://www.yachtsurvey.com/Fiberglass_Boats.htm

 

The lifespan of modern composites is certainly limited, manufacturers would be hard pressed to specify a product life span. I think they would be safe working on 10 years.

The adhesives used to bond the laminates have a finite life (and are often improperly applied). De-lamination in modern composites is a hard repair. I have seen large areas of outer skin delamination in the bow areas of modern vessels. I also see my fair share of ripped out chain plates over stressed rigging attachments, cracked keel hull joins, torn out engine mounts attachments and bulkhead delamination. All repaired under the owners insurance.

Increasingly this damage is coming from the contemporary light performance cruisers caught in bad weather. Some of these boats are only a few years old.

I think the fault is in the designers presumption of total strength of the laminate without allowing for the variables of adhesive performance. But that design is only for global vesssel strength, there is no or very little safety factor for collisions or rough handling.

Solid GRP has a major life problem too, the resin breaks down eventually in the water which is always present in the resin . I think it is safe to say that all grp hulls over 10 years old have some degree of osmosis, this gets worse with age often becoming a major repair at 30 years.

I can't see modern composites safely lasting 15 years of service.

 

I agree. Also with Mike Johns. My good old Banjer (35 years), although having developed hydrolysis in outer laminates, still kept a nice hull strength because of her proper scantlings. Just a matter of a proper surface job to give her another 35. Most of modern light boats will not stand the test of time, in my opinion, unless kept out of water for long periods in winters, or the like.

Also agree with Mike Johns about life expectancy and problems of modern composites. Fatigue problems and weathering are not still well documented, and I've heard of first problems arising. There's even a reputed author (not remember now his name), writing about wood-epoxy techniques saying we may be before a time bomb.

Boats should have a long life span expectancy and to that end probably an isophtalic resins hull properly scantled with a nice safety factor in it, will still be a good combination, providing forgiving and easily repaired boats, with a long and satisfactory life even if in not so caring hands.

 

"I can't see modern composites safely lasting 15 years of service."
I think that is a wild generalisation.
And just what do you mean by modern composites?And, more to the point, from who's yard.
If you mean polyester/csm/wr/balsa. etc, bollocks, because I know of several
20yr old boats that have been raced continously over that period and are in good nick. I also know of some that are in not so good shape; All depends on
the workmanship of the builder and their attention to detail. (scantlings and material handling)
And most importantly, on any boat,maintenance.
If you are talking about epoxy encapsulated strip cedar, double bollocks.
Give us your case histories.
Production boats maybe, but then what do you expect in the market place?
Also,as soon as you add the word performance,the SF goes out the door for
the average punter.

 

Finally this thread seems to have come to life and I hope to learn something out of it.

Some time ago I was questioning two different small production boat builders about the strength and durability of their fiberglass boats. In both cases I was talking with the owner of the shipyard and both it happened that the guys were also the designers of their boats. Very knowledgeable guys and their boats are top market boats.
Each of them told me that their boat was as strong and durable as the boat of his competitor (nice guys) but fact is that the material and composites used were very different.

I got the impression that they have confidence in their building techniques, they know they are doing the best the market produces, but also that regarding the durability of the materials they are using, regarding life expectancy, they don’t have a clue.

Fact is that I have been searching and I found nothing on the durability of modern composites, and yet, boats are assumed to last 30 years.

The only real lab study that I have found, the one by Professor Paul Miller, talked about a 50% loss of stiffness on a 20 year old boat, due to stress, and that is huge.

Fact is that in a fiberglass boat you have no way of telling if an old boat is safe. The boat can look alright and lose its keel due to a huge diminution of strength in that area due to many years stress that have never been taken into account when the boat was designed.

I remember that in the 60’s (or 70’s?), suddenly a lot of commercial airplanes started to crash, and only then have they started to talk about metal fatigue and stipulated time limits for the substitution of each piece. I hope that a similar thing is not going to happen in the boat industry even if I think that it will probably happen.

Modern boats are better performers than the old ones, but for that they have to be light. They are computer calculated with sufficient safety margins but I doubt that stress over the time and durability of glues and materials is taken into account…and people still think boats will last 30 years.

Regarding the old ones, as Mike has said, it is not only a problem of osmosis. The water content accelerates the resin break down and the boat becomes brittle, losing the capacity to flex. Old boats were not computer designed and are much stronger (and heavier) than they needed to be, at the time they were built, and that margin has given them some safety margin, but that margin is being eroded by time and it will come a time when serious problems will arise.

Problem is that serious lab studies in that area (GRP and composite durability) are almost inexistent.

We rely on surveyors and engineers like Mike, who look at the time effects in thousands of boats, to keep us informed, and to ultimately, demand serious studies on this subject.

 

Roly
A fairly vicious troll with a slight accord at the end?

I probably should have expanded in that earlier post …really the lifespan will be down to a finite number of stress cycles rather than a particular length of time but people don’t always relate well to engineering papers… so yes it is a generalisation .

In all general observations it is the trend we are concerned with rather than the case of personally known exceptions. For example balsa cored hulls are often a disaster even though you may be aware of such vessels still in good shape. Ditto for any material .

Modern materials …. are just that…., materials that have become available recently and are still out to the jury as far as durability is concerned. Particularly I am referring to the cored hulls. GRP is of course a composite itself but the industry refers to the cored hulls as composite construction. In the past Engineers have voiced doubts long before the public starts to reject the materials. The past failures are out there…. abysmal engineering materials that should never have been produced in the first place ( I can quote several ) .

The big problem is lack of real R&D amongst the core manufacturers, some pretty extravagant claims and a poor understanding of the conditions that tend to prevail both in the applied stresses and in the water content that ends up present in the lay-up.

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.

The composites suffer from bond failure due to that moisture and the core materials even when supposedly closed cell waterproof material absorbs water too. This moisture changes the nature of the materials, for example fatigue strength of most materials drops significantly in the presence of a certain level of moisture. Try and get test data from the core material manufacturers to say that the cores will stand up to the recommended application, you will find that they tested flat panels perfectly bonded in temp stable dry workshops. Compare that with the recommended tests for marine ply!


All the foams in the best of conditions have low shear strength (Balsa is good there) means that any stresses that put the core in shear tend to cause significant distortion of the panel, the laminates do not respond well to bending and local delamination or inter core-failure is common in areas of high repeated stresses. Don’t believe the marketing hype either, these materials only produce stronger panels in and under certain conditions.
Some of the closed cell foams change their strength significantly with temperature, get a dark hulled boat and the outer laminate on the sunny side can be considerably longer than the inner laminate the core has poor shear strength and loses strength with the increase in temp, a few of these cycles can really loosen things up.

Racing hull designers/builders are particularly not interested in longevity, for example modern techniques allow thinner lighter skins for a given strength through vacuum moulding techniques, (IMO when you start vacuum moulding large hulls in expensive materials so you can save a few 10’s of kilo’s on your scantlings you know things have gone troppo ..) These sorts of vessel have a lower projected life again…highly stressed lightweights.

Production boat makers like the lower cost and reduced resin cost of cored hulls, global stiffness fatigue, delamination and some dubious materials appearing on the scene all ring alarm bells……..and not just in my head. When you start relying on adhesive bonds for the full section modulus you really should be darn sure of that adhesive bond. The bonding agents are often poorly applied and there is no satisfactory way of testing what percentage of area has adequately bonded. In reality 100% is never achieved . Hurricane damaged boats have shown that there are often large areas of no bond. Damaged boats have given a valuable and accelerated insight into the performance of many of the core materials and in general it has been very poor indeed when compared with solid GRP.

Course if you float around in the marina and use the boat as a drinks platform then its all ok but much of this competitive industry builds them light and fixes the ones that break as their policy (rather than building them so they never break). There are yards that build quality strong hulls but they don’t use cores in the hull.

As for case studies ……Production hulls from top quality builders like Bertram are good although they had their own disasters trialling core materials ( re-called), the highly marketed expensive gin platforms and their look-alikes are usually very poor ( and will remain unnamed ) and are often best as semi sheltered water craft, despite their large size and marketing boasts they target vanity rather than function. If you were actually sailing on these world cruising I would expect significant ongoing repair and what I would term significant damage suggesting end of economic life after only a few years. Many of these boats I would not sleep well on at sea.

A bit of a ramble , but you can see where I am coming from .

 

Yep! But look what I hooked.
Bear with me please, Work is calling;I have only a few questions.(<100!)

 

Mike,

I'd sleep a hell of a lot better in a vacuum-bagged boat out in the ocean than in a clunker laminated by campesinos who have little training or understanding of composites.

Yoke.

 

I'm afraid I do not fully understand your statement. Water may hydrolize the resins making the laminates softer and more prone to give way when under load.... FRP laminates are brittle when they have an excess of resin.

A good and well fundamented article on hydrolisis, osmosis, blisters and the like:
http://www.zahnisers.com/repair/blister/blister1.htm
There was another very good one, "FRP boats" by Jeffrey N Casciani-Wood, but unluckily his company's site seems not to be working anymore....

I'm afraid fact is, yes, you have. Just a matter of getting samples and sending them to the lab. And a quailified surveyor may even have a pretty accurate idea without the needing of a lab. You probably mean 'by simple ocular inspection'.

Some papers on FRP laminates fatigue:
http://www.usc.edu/dept/civil_eng/johnsone/pmc2000/sessions/papers/p302.pdf
http://www.stormingmedia.us/35/3532/A353243.html
http://www.scielo.br/pdf/mr/v8n1/a09v8n1.pdf
http://www.netcomposites.com/netcommerce_features.asp?835
http://www.mdi.espci.fr/~chateau/Fatigue/fatigue.html

And an intersting site:
http://users.ugent.be/~wvpaepeg/fatigue/composites.html

 

What Japanese are doing with disused GRP boats

Recycling Technology for Disused FRP Boats in Cement Burning Process
Author : Shigeru AKIYAMA, Shinya HAYASHI, Kazuyoshi MATSUOKA, Kenichi KATSUMATA, Takeshi NARUSE, Akio SAKURAI, Kojiro YOSHIDA, Kenji YAMANE, Noriyuki KOTANI, Nobuhiko YAMAUCHI and Syuji NAKANISHI
Abstract

　　"More than 45 years ago, Fiber Reinforced Plastics( FRP) was successfully applied to the main parts of small boat structures. At present the total amount of the disused FRP boats is estimated to be about 5,000 tons, that is to say7,000- 12,000 boats in total number, per year. They are, including the sunken boats, often unlawfully left on the river or at the port.
　　　On the other hand, the concern in Japan for the recycling of waste materials has increased enormously in recent years. This is because the lack of the space for“ landfill” has become serious, and the" Recycling Law" has been effective since 1993. Therefore, the treating and the recycling of the disused FRP boats are also the keen social issues.
　　　Many investigations on disposal of the disused FRP boats were made in 1973 and the 1980s. As a result, several apparatuses for waste disposal or recycling were developed for disused FRP boats. However, they were not commercialized because of the high cost.
　　　Since fiscal 2000, we have carried out the project named "Sophisticated Recycling System for Disused FRP Boats". We established the new recycling system for the crashed FRP pieces of disused FRP boats, which are used as fuel and raw materials in the cement burning process without any other residue. And the recycling plant was developed to mix FRP with recycling oil as moistener."

 

I have repaired approx. 25 older sailing craft 30 to 50 ft. in 3 years. They had osmosis damage of several types and I have come to believe it reflects the efficiency of the builders. Granted, osmosis is basically the result of the use of low cost General Purpose Polyester to build even well respected boat names in the 70s, 80,s and 90s. Gel coats were permeable and iso vrs ortho polyesters equated to dollars, simple as that. Hulls were as thin as 1/4 inch and 3/4 inch in some. Most had spent time in the Hurricane hole at Rio Dulce, Guatamala. The water there is fresh to brackish and fresh seems to accelerate the osmosis process. You could see more damage on the sunny side of the hull which relates to warmer water, especially at the water line. Todays boats are built using Vinyl Ester as the outer shell. It is much more resistant to permeability. Nearly as good as Epoxy which I use to make repairs. There are the spots that look the size of a quarter that get ground out to "bleed". There are areas that require grinding as big as 24" square and there are some that appear to be one faulty layer back in the laminate.
OK, if you are buying an older boat this would imply that the thicker hull would at least have the integrety to be repaired.
If anybody is interested I can point you to a US Coastguard sponsored research report on Osmosis.

 

I have repaired approx. 25 older sailing craft 30 to 50 ft. in 3 years. They had osmosis damage of several types and I have come to believe it reflects the efficiency of the builders. Granted, osmosis is basically the result of the use of low cost General Purpose Polyester to build even well respected boat names in the 70s, 80,s and 90s. Gel coats were permeable and iso vrs ortho polyesters equated to dollars, simple as that. Hulls were as thin as 1/4 inch and 3/4 inch in some. Most had spent time in the Hurricane hole at Rio Dulce, Guatamala. The water there is fresh to brackish and fresh seems to accelerate the osmosis process. You could see more damage on the sunny side of the hull which relates to warmer water, especially at the water line. Todays boats are built using Vinyl Ester as the outer shell. It is much more resistant to permeability. Nearly as good as Epoxy which I use to make repairs. There are the spots that look the size of a quarter that get ground out to "bleed". There are areas that require grinding as big as 24" square and there are some that appear to be one faulty layer back in the laminate.
OK, if you are buying an older boat this would imply that the thicker hull would at least have the integrety to be repaired.
If anybody is interested I can point you to a US Coastguard sponsored research report on Osmosis.

 

Mike,
Long day; My apologies if I seemed rude. My tongue is under control now.
Thankyou for your clarification,however discouraging it is.

If you have a data base of failures I would be keen to view it. Especially in the more "balanced" composites. (Epoxy/cedar.)

Roly

 

Guillermo,
Let me clarify the hydrolize statement as simply as I can. It is a Chemistry problem. Polyester is created (oversimplified) by the removal of water from the reaction of styrene etc. etc.. When the reaction reaches a certain point chemicals are introduced to stop the reaction. The results are drummed off and sold. The user adds catylist which reignites the cross linking process and the polyester gets hard. That is the reason a drum of resin will get thicker over time and heat even without hardener. Now for the bad news. Polyester never fully cures. The head resins Chemist at Owens Corning resins delivered a paper (just before he retired) to SPE about 25 years ago which proved that. OK, Over time the fact that a boat sits in water allows water to migrate in and along the fibers where it finds molecular voids containing unreacted Styrene. The water vapor reacts with it and creates an acidic (vinegar smelling) compound which gasses to swell the area and actually split the laminate, Hense the "blister". Studies have suggested that the water, that was originally removed, is trying to reintroduce itself, returning the polyester to it's liquid state.
In the early to mid 1940s when I started as a kid working with the stuff, (making nose cones for experimental guided missles) it was the answer to a maidens prayer because it was cheap, and easy to work with. Boat after boat was switched to fiberglas and nobody knew that problems could occur. Well now we know and Vinyl Ester is the material of choice to barrier the outer surface of a bigger boat.
GRIN, Thank me for not going into detail!!! You would all be asleep by now.
RUSS

 

VEGA,
thanks for the link to the Pascoe report. Just read it all and it was impressive. His reference to cored boats was also "right on".
Doesnt sound like we have progressed very much does it.