On Fri, 26 Mar 2010 10:51:31 +0100, "Steve Lusardi"
wrote:

I do not think Microwave heating to eliminate moisture in fiberglass is practical. The oven in a microwave unit is a reflective
cavity. You would have to have a reflective chamber the size of the boat and a several megawatts of RF to be effective. There
would be dead spots and spots of excessive heating, just like in a microwave oven. Even if you would do this, you would still have
to provide a means of absorbing the moisture generated in the chamber's air. (Basic gas laws and equilibrium apply) There are more
practical ways of achieving this. It is important to understand the problem in order to find a solution. No construction material
lasts forever. They each have their disadvantages and advantages and a finite life. The failure mode of all fiber based plastics
are UV driven disintegration and osmosis. Osmosis is the wicking effect all fibers have when exposed to a liquid, which causes
hydraulic delamination at the weakest bond. Although FG is not waterproof, it is not readily permeable either and there is your
dilemma. Once moisture has invaded the material, it is next to impossible to get it all out.Even though fiberglass boat
construction has been around since the 50's, there are not many boats still around that old. The cost of FG hull maintenance is
only exceeded by wood. All other materials have a better TCO (total cost of ownership). I'm sure that statement will generate some
flames, but it is observable and self evident,
Steve.



I'm sure that you are correct regarding the micro-wave method of
drying a hull as in the article, I read, the writer sounded as though
he had discovered sex and was going to start a company to bring his
innovative methods to the multitudes. Certainly he stated that he had
dried his own deck, or parts of his deck, but I never read another
word about his company of anyone else using salvaged micro-wave ovens
to dry boats.

There also was an article, in Practical Boat Owner, about one of the
their staff who had purchased what was apparently one of the first
fiberglass yachts ever built commercial in the U.K.

For whatever reason the owner, or perhaps the surveyor, cut cores out
of the hull and had them tested. The cores tested at 90-something
percent of the calculated original strength of the hull material.

There was no mention of the boat's history or how much time it had
spent in the water, and in England many boats are hauled out for part
of each year, so the testing was hardly a comprehensive study but, as
the magazine wrote, it did show that fiberglass did not deteriorate
greatly with age.

Regarding the cost of wooden boats, there was another article in the
same magazine written by a bloke who was something of a pundit
regarding wooden boats. He had a "Channel Cutter" that had been built
in 1800-something, and after years and years had sold it. Apparently
there was a great hue and cry, he was a traitor to the traditional
boat world, and on and on.. His article was in justification of his
decision. He simply described, in detail, the trials, tribulations,
and costs of owning a wooden boat of great age. It was an eye opener
as the boat had required substantial repairs nearly every year since
he had owned it. Port garboard replaced, four ribs replaced, portions
of the deck relayed, recaulked hull, etc.

What most people don't realize when they see a wooden boat that when
they were built their life was usually expected to be about 10 years
and many of them were only afloat for a few years - read the history
of the tea clippers.

I once knew Chester Carter who's family had built boats on Miscongus
Bay, in Maine for generations. He told me that the conventional Maine
built work boat, oak timbers, cedar planking, fastened with galvanize
boat nails, would last about ten years and then needed refastening and
might last another five or six years after that. He was well aware of
fiberglass construction and didn't think much of it - not because it
was fiberglass but because it was lighter then wood and bounced around
a lot. He used to say things like "well, you should try pulling pots
in one of those things, jumping around like a rabbit".

Cheers,

Bruce

Bruce writes:

For whatever reason the owner, or perhaps the surveyor, cut cores out
of the hull and had them tested. The cores tested at 90-something
percent of the calculated original strength of the hull material.

I find it highly unlikely they could calculate the original strength
with a 10% inaccuracy. The materials used were not characterized that
well and the variation in the lamination process is much bigger. I
have been told by a senior structural engineering consultant that
the uncertainty in fatigue life for the materials we know best--
structural steels -- is roughly 6%. Composites, even aerospace
qualities, are much, much harder to get good data on.

There was no mention of the boat's history or how much time it had
spent in the water, and in England many boats are hauled out for part
of each year, so the testing was hardly a comprehensive study but, as
the magazine wrote, it did show that fiberglass did not deteriorate
greatly with age.

This is pure nonsense. Fiberglass laminates have limited fatigue life as
do all materials.

This boat has lived a pampered life relative to its scantlings.

/Martin
http://hem.bredband.net/b262106/

On Sat, 27 Mar 2010 10:07:40 +0100, (Martin
Schöön) wrote:

Bruce writes:

For whatever reason the owner, or perhaps the surveyor, cut cores out
of the hull and had them tested. The cores tested at 90-something
percent of the calculated original strength of the hull material.

I find it highly unlikely they could calculate the original strength
with a 10% inaccuracy. The materials used were not characterized that
well and the variation in the lamination process is much bigger. I
have been told by a senior structural engineering consultant that
the uncertainty in fatigue life for the materials we know best--
structural steels -- is roughly 6%. Composites, even aerospace
qualities, are much, much harder to get good data on.

I am not sure whether they had sufficient data to do accurate strength
calculations although I had a book written back in he very early days
of fiberglass boat building by someone who was described as an expert,
that did list tensile strengths for various boat building materials
and certainly there would have been tests made before publishing such
a table.

Having said that, certainly there is a variance in strength of a
fiberglass structure that varies with all kind of things - chemical
makeup of the actual resin used, hardener/catalysis mix, amount of
glass and resin in the structure and so on. I assume that why they
said calculated strength.

There was no mention of the boat's history or how much time it had
spent in the water, and in England many boats are hauled out for part
of each year, so the testing was hardly a comprehensive study but, as
the magazine wrote, it did show that fiberglass did not deteriorate
greatly with age.

This is pure nonsense. Fiberglass laminates have limited fatigue life as
do all materials.

I didn't say that it didn't deteriorate with age, I said it didn't
deteriorate GREATLY with age.

This boat has lived a pampered life relative to its scantlings.

/Martin
http://hem.bredband.net/b262106/
Cheers,

Bruce

If you want to make your wood boat last a long time, you must fasten
it with something that won't rust, you must keep it dry inside, but most
of all you must wash it down morning and evening with salt water!
Gordon

course, you have to protect the bottom from the borers also.

On Fri, 26 Mar 2010 10:51:31 +0100, "Steve Lusardi"
wrote:

All other materials have a better TCO (total cost of ownership). I'm sure that statement will generate some
flames, but it is observable and self evident

So which is cheapest, steel or aluminum ?

We are seeing a lot of steel sailboats from Europe with semi-hard
chines down here in the Caribbean. Some are showing rust streaks but
most seem to be holding up fairly well.

On Mon, 29 Mar 2010 17:15:54 -0400, Wayne.B
wrote:

On Fri, 26 Mar 2010 10:51:31 +0100, "Steve Lusardi"
wrote:

All other materials have a better TCO (total cost of ownership). I'm sure that statement will generate some
flames, but it is observable and self evident

So which is cheapest, steel or aluminum ?

We are seeing a lot of steel sailboats from Europe with semi-hard
chines down here in the Caribbean. Some are showing rust streaks but
most seem to be holding up fairly well.

It depends a lot on how the vessel is built.

A steel boat that used stainless everywhere there is chafe or wear -
rail cap, all exposed bolt or pin holes bushed, stainless cleats and
fairleads, any dissimilar metals insulated, no wood, teak decks,
cockpit combings, etc., the electrical system totally insulated from
the hull and an alert captain or crew that catches every scratch that
appears will certainly not require much, if any, major maintenance for
very long periods.

On the other hand I know a chap that has a French built aluminum
sloop. Electrical system insulated from the hull, anything that is in
the water is either aluminum or some alloy that doesn't react with
aluminum strongly. To the best of my knowledge the only major
maintenance he has done in probably 20 years is to overhaul the main
engine.

You often see French built boats that are unpainted aluminum, except
for the anti-fouling. They appear to have few problems.

And finally you see the home built boats, built by amateurs, that seem
to rust away in 10 years or sometimes less.

I believe that you are a power boat man so have a look at Seahorse
Yachts, the Diesel Ducks, I did a bit of work on one when it came
through Thailand on its way to the U.S. Beautiful work.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)