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Old 09-15-2011, 06:57 PM   #1
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What's the life expectancy of a glass hull?

A lot of our boats are now 30 plus years old, and *when they were laid down fiberglass was a pretty new material.

Has there been any research into* life expectancy*of fiberglass that is submerged 24/7 in salt water, given that any material will eventually degrade.*
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Old 09-15-2011, 07:32 PM   #2
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RE: What's the life expectancy of a glass hull?

From Cruisersforum.com:

As I said in a prior thread on this subject, I would not think that fiberglass has a life span per se. Neither concrete nor fiberglass truly breaks down or loses strength on their own. They require other causes. In the case of fiberglass loss of strength can result from one or more of the following,

-The surface resins will UV degrade.
-Prolonged saturation with water will affect the byproducts formed in the hardening process turning some into acids. These acids can break down the bond between the glass reinforcing and the resin.
-Fiberglass is prone to fatigue in areas repetitively loaded and unloaded at the point where it is repetitively deflected. High load concentration areas such as at bulkheads, hull/deck joints and keel joints are particularly prone.
-Salts suspended in water will move through some of the larger capillaries within the matrix. At some point these salts are deposited as the water keeps moving toward an area with lower moisture content. Once dried these salt turn into a crystalline form and exert great pressure on the adjacent matrix.
-Poor construction techniques with poorly handled cloth, poorly mixed or over accelerated resins, and poor resin to fiber ratios were very typical in early fiberglass boats. These weaker areas can be actually subjected to higher stresses that result from much heavier boats. Its not all that unusual to see small spider cracking and/or small fractures in early glass boats.
-Of course beyond the simple fiberglass degradation there is core deterioration, and the deterioration of such things as the plywood bulkheads and flats that form a part of the boats structure.

In a study performed by the marine insurance industry looking at claims on older boats and doing destructive testing on older hull materials, it was found that many of these earlier boats have suffered a significant loss of ductility and impact resistance. This problem is especially prevalent in heavier uncored boats constructed even as late as the 1980's before internal structural framing systems became the norm. Boats built during the early years of boat building tended to use a lot more accelerators than we use today. They also would bulk up the matrix with resin rich laminations (approaching 50/50 ratios rather than the idea 30/70) non-directional fabrics (mat or chopped glass) in order to achieve a desired hull thickness. Resin rich laminates and non-directional materials have been shown to reduce impact resistance and to increase the tendency towards fatigue. The absence of internal framing means that there is greater flexure in these older boats and that flexure increases fatigue further. Apparently, there are an increasing number of marine insurance underwriters refusing to insure older boats because of these issues.

There are probably other forms of degradation that I have not thought of but I think that the real end of the life of a boat is going to be economic. In other words the cost to maintain and repair an old boat will get to be far beyond what it is worth in the marketplace. I would guess this was the end of more wooden boats than rot.

You may find a boat that has a perfectly sound hull. Perhaps it needs sails, standing and running rigging, a bit of galley updating, some minor electronics, a bit or rewiring, new plumbing, upholstery, a little deck core work, an engine rebuild, or for the big spender, replacement. Pretty soon you can buy a much newer boat with all relatively new gear for less than youd have in the old girl. Its not hard for an old boat to suddenly be worth more as salvage than as a boat. A couple years ago a couple friends of mine were given a Rainbow in reasonable shape. She just needed sails and they wanted an auxiliary, but even buying everything used the boat was worth a lot less than the cost of the new parts. When they couldnt afford the slip fees, the Rainbow was disposed of. She now graces a landfill and the cast iron keel was sold for scrap for more than they could sell the whole boat for.

Wooden boats represent the difference between a maintainable construction method versus a low maintenance. A wooden boat can be rebuilt for a nearly infinite period of time until it becomes a sailing equivalent of George Washingtons axe (as in thats George Washingtons axe. Its had a few new handles and a few new heads but that is still George Washingtons axe.)

And finally if you buy an old fiberglass boat, paint the bilges white. It does nothing for the boat, but if you ever have to sell the boat, then someone may look in your bilge and say Lets buy her because any man that would love a boat so much that he went through the trouble to paint the bilge white must have enjoyed this boat and taken great care of her no matter what her age.
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Old 09-16-2011, 04:25 AM   #3
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RE: What's the life expectancy of a glass hull?

"And finally if you buy an old fiberglass boat, paint the bilges white."

Early boats did not use gel coat in the bilge area , so age or a grounding that might crack the glass below the cabin sole could be seen.

A painted bilge to me would be a turn off , a way to hide structural hull damage.

The USCG wants stiff boats , roughly 400% over what the normal loads are.

They have found if the boat is stiff enough , it stays together.

Their method for obtaining stiffness , thick hulls , solid or cored , just NO FLEXING.
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Old 09-16-2011, 04:34 AM   #4
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RE: What's the life expectancy of a glass hull?

Quote:
FF wrote:

The USCG wants stiff boats , roughly 400% over what the normal loads are.

They have found if the boat is stiff enough , it stays together.

Their method for obtaining stiffness , thick hulls , solid or cored , just NO FLEXING.

*Sometimes the CG gets what they ask for and we have to pay for it.

http://www.nytimes.com/2006/12/09/us...pagewanted=all

The article is old but the lawsuit has been heating up over the past few weeks.

Sorry to hijack the thread but it was too good a lead-in to pass up.
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Old 09-16-2011, 09:24 AM   #5
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RE: What's the life expectancy of a glass hull?

"The Coast Guard hired Lockheed Martin and Northrop Grumman, two of the nations largest military contractors, to plan, supervise and deliver the new vessels and helicopters."


Not bright , but that's why all those admirals retire into the MI complex.Good Rolladex.

They would have had far better luck with boat builders , rather than tax eaters.

If you want a huge laugh look up what happened when congress (not understanding the difference between a monopoly and a de facto monopoly,,, a great product at a low cost that its not worth competing) decided they would pay 40% more for non GM city coaches.

The Flxible corp got bought by Grumman which eventually had to EAT a few thousand buses.

Interesting my favorite iron mongers , the Brits , were bright enough to take plaster casts of NYC potholes and build a test track.

After 2 years attempt , they said NO THANKS!!

In the end GM simply spun off the bus division , so "someone else" is building the buses.
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Old 09-17-2011, 10:09 AM   #6
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RE: What's the life expectancy of a glass hull?

Thanks Kieth for the very informative post.
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Old 09-18-2011, 06:54 PM   #7
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RE: What's the life expectancy of a glass hull?

Quote:
nomadwilly wrote:
Thanks Kieth for the very informative post.
*Yep, that pretty much answers that question.

At the risk of hijacking my own thread, FF I'm interested in that bit about a English bus company looking at the NY road systems. I used to own a London Routemaster bus back in the 80's(it's the traditional London bus with the open back platform)

IMHO the BEST bus ever made*
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