Older Boats-How Long will they Last? - Page 4 - SailNet Community
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post #31 of 79 Old 07-08-2007
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Tartan34C,
So you are saying I should try to base my technical posts on fact rather than some wild ass garbage I heard from some old dude in the marina that looked like he knew some stuff about boats???...........bummer.
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post #32 of 79 Old 07-08-2007
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Quote:
Originally Posted by poopdeckpappy
But with all that aside, it still comes down to who throws out the ghost first, and it's usually the owners.
I suppose by that logic, an 80 year old owner of a "classic plastic" would be well advised to sell only to a 65 year old new retiree with plenty of bucks, skills and time to do deck recorings, rotted stringer replacements and engine rebuilds.

Then the 65 year old gets a good 15 years until the boat is finally finished.
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post #33 of 79 Old 07-08-2007
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Whenever I think about the day when age might be an issue with a glass boat, I look to examples like this:
Atom Voyages | Islander Taipan 28 Refit Photos
Shows what happens when a boat is built with lighter GRP and inferior products, and what can be done to make it better than new. All said and done, it's still a lot less expensive than buying a new one. And then there's the now 43 y/o Glissando, found in a field, open to the elements for who knows how long. The cored deck needed replacement, but the non-cored, too thick glass hull was fine.
Pearson Triton #381 Glissando | Preparing the Hull for Painting

Last edited by seabreeze_97; 07-08-2007 at 10:12 PM.
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post #34 of 79 Old 07-08-2007
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Quote:
Originally Posted by Valiente
I suppose by that logic, an 80 year old owner of a "classic plastic" would be well advised to sell only to a 65 year old new retiree with plenty of bucks, skills and time to do deck recorings, rotted stringer replacements and engine rebuilds.

Then the 65 year old gets a good 15 years until the boat is finally finished.
Huh ????

Doesn't matter if your 25,65,or 105, the point was, it don't matter how old the boat is, as long as you want to keep it alive, then you'll keep it alive

1955 Blanchard 51 Custom ( I got a woody )

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post #35 of 79 Old 07-08-2007
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Quote:
Originally Posted by danjarch
A better way to learn about long term effect on materials is to look at airplanes. A airplanes fuselage almost never comes into contact with any other hard objects. However, after repeated long term flexing, it will start to crack, then rips apart. If you took a fiberglass boat, and continuously sailed it with out ever bumping into anything, it would start to crack and then rip apart.
Danjarch,

What you're talking about is fatigue. Fatigue occurs when materials are repeatedly loaded and unloaded with stress above their endurance limits.

For fiberglass, the endurance limit is about 25% of its strength -- if the cyclic working stresses stay under this level, it doesn't fatigue.

Older boats were way overbuilt by today's standards. I have drawings here for a 46 foot ketch from the early 60s. Its topsides over the front half of the boat are a full 3/4" thick, tapering to 1/2" at the transom. Below the waterline it gets thicker yet. It also has structural stringers and bulkheads. Using the American Bureau of Shipping rule for composite boat scantlings, this hull is close to twice as thick as the rule today calls for. The strength of panels in bending goes up with the square of the thickness, so the stress in the fiberglass of this hull would be about a quarter of the stress seen in the ABS spec hull. Hulls like this will never fatigue.

Comparing fatigue in aircraft and boats is apples and oranges. Aircraft need to be as light as possible to fly. The factor of safety is typically 1.1, that is, the strength of each part of a plane is only 10% greater than the maximum load they expect that part to see. The stresses are much closer to the material's strength, and fatigue sets in quite quickly (thousands of cycles instead of millions or billions).

Boats, on the other hand, are designed to considerably higher factors of safety. Planing powerboats need to be light to plane, and they do lots of pounding on waves, so they do get into the stress levels that fatigue fiberglass. Racing sailboats are designed to be as light as possible so they put their hulls under high stress loads and they fatigue too (what people mean when they say a hull has become "soft"). Cruising boats, however, especially old heavily built ones, are much less likely to fail from fatigue.

So, getting back to the original poster's question, I say there's a lot of life left in that Alberg.

Cheers,

Tim
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post #36 of 79 Old 07-08-2007
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How long will a fiberglass boat last in dog years?
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post #37 of 79 Old 07-08-2007
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I figure a well-built GRP boat should last at least 300 dog years...

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post #38 of 79 Old 07-09-2007
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Quote:
Originally Posted by camaraderie
Well...since FG boat building came into its own about 40 years ago...we should be seeing reports of hulls failing due to age...yet I've never seen anything posted here or elsewhere about that. Blisters yeah...but that affects younger boats as well.
I am of the opinion that speculation on the longevity of FG boats is just that at this point and we really don't know how long they will last. A well built boat from the 70's like Pappy's may indeed have another 30 years or more of life and I would not hesitate to buy a boat of that era that surveys well.
I have a '76 Swan that is built like a tank and I would certainly think I'm going to get more than another ten years out of her. I think that 40 year figure is pulled out of thin air.
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post #39 of 79 Old 07-09-2007
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Quote:
Originally Posted by poopdeckpappy
Huh ????

Doesn't matter if your 25,65,or 105, the point was, it don't matter how old the boat is, as long as you want to keep it alive, then you'll keep it alive
True, but a 25 year old might have neither the time, the skills or the money to keep an aging GRP boat alive, or even on life support. If someone is getting too old to sail, as some 80 year olds are, then it's conceivable that selling it to a 65 year old, who keeps it for 15 years and then repeats the process, could extend the life of a plastic boat farther into the future than we could expect.

I know more than one young-ish person (sub-40) who bought an old sailboat for a few years only to have to sell it because while they could afford a $10K 30 footer from the '70s, they couldn't afford the time for maintaining it, having a job, a house, a spouse, kids and "other interests". The old boat, sucking time and money, ends up getting fire-sold to somebody else...until it finds an owner who can keep it alive, thanks to having spare time, some cash, and the skills.
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post #40 of 79 Old 07-09-2007
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There is a fiberglass 1959 Rawson 30 in my marina. Yes, it is FRP. Very THICK fiberglass. All the way around. Ron Rawson was one of the pioneers in fiberglass boat building. The joke around Puget Sound was/is you could drop a Rawson from the Space Needle and sail it away. From the looks and feel of the boat, it's going to last another 48 years... (Just my amatuer opinion.)


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