Moisture meters
 

One of our regulars, who is a bit shy about himself and his boat, asked me
some questions privately that I can't amswer. My experience and knowledge
concerning fiberglass boats is pretty much limited to owning one.
Professionally, I'm a metal boat designer.

Now, I'd like to know the answer.

If you have your boat surveyed and the moisture meter shows high readings in
an area of cored deck that otherwise seems solid, is that really a problem?
How can the meter read moisture in the core under 1/8 to 1/4 inch of
fiberglass and determine that it is not just surface moisture? Do these
gadgets have anything useful to tell you about fiberglass condition? Are
they any use on a solid glass hull?

When I was looking for my E 32, which has solid glass decks with plywood
bonded underneath in critical spots, I didn't look at one that the broker
said had some high moisture readings in the decks. I've often wondered just
what that meant. The boat we ended up buying was reported to have very dry
decks so I didn't give the subject any further thought until this.

--
Roger Long

Moisture meters
 

Yo Roger .. it is ok to tell the group it is me...

I was on the boat today. After your thoughtful reply, and some other input,
as well as my close examination of the areas of high
moisture .. I plan on rebedding all hardware [ I was doing this anyway ] and
I am also going to seal the deck with epoxy two part paint. Then paint with
a non skid deck paint.

I will also drill some holes in a few spots, let out the moisture and apply
acetone .. the acetone will suck out moisture according to
someone on my other boat group.

The deck is sound, no mushy or with any give.

The surveyor who looked at my boat on Saturday told me his professional
organization recommends sealing the deck is tight as possible before any
surgery. He said moisture without oxygen is not going to do much of
anything. According to him it is the oxygen that is the culprit.


Let's face it, my boat is 32 years old. After 32 years, it isn't going to
be perfect. Add to this a previous owner who didn't rebed the hardware. He
was a good owner, don't get me wrong. He loved the boat, did many upgrades.
He just didn't get around to rebedding.

I am taking off all the hardware. Should have her clean by Sunday. Then,
drill, epoxy, redrill, seal,, etc.

It is always something with boats.

-
"Roger Long" wrote in message
...
One of our regulars, who is a bit shy about himself and his boat, asked me
some questions privately that I can't amswer. My experience and knowledge
concerning fiberglass boats is pretty much limited to owning one.
Professionally, I'm a metal boat designer.

Now, I'd like to know the answer.

If you have your boat surveyed and the moisture meter shows high readings
in an area of cored deck that otherwise seems solid, is that really a
problem? How can the meter read moisture in the core under 1/8 to 1/4 inch
of fiberglass and determine that it is not just surface moisture? Do
these gadgets have anything useful to tell you about fiberglass condition?
Are they any use on a solid glass hull?

When I was looking for my E 32, which has solid glass decks with plywood
bonded underneath in critical spots, I didn't look at one that the broker
said had some high moisture readings in the decks. I've often wondered
just what that meant. The boat we ended up buying was reported to have
very dry decks so I didn't give the subject any further thought until
this.

--
Roger Long

Moisture meters
 

Dave wrote:
On Wed, 28 Mar 2007 00:57:04 GMT, "NE Sailboat"
said:

I will also drill some holes in a few spots, let out the moisture
and apply acetone .. the acetone will suck out moisture according to
someone on my other boat group.

Based on what I've read, I'd be skeptical of that. But let us know if
it works.

I though Charlie's explanation was a pretty good one.

Someone is pulling your leg. Acetone is excellent for removing hardened
resin from the hands and other areas of inadvertant pollution. Maybe it will
do the same for your deck! Treat this one with caution!

Dennis.

Moisture meters
 

The acetone sounds dodgy to me but it might work for different reasons. Rot
I do know a bit about from my early days with wooden boats although I'm
remembering back a quarter century.

Rot is a fungus that thrives within a very narrow range of moisture
conditions. Water alone doesn't rot wood although it might break down bonds
between balsa and fiberglass when aided by the impact of feet. Acetone
fumes might kill or slow down the fungus although I've never heard such a
thing. It might also accelerate the separation of balsa and fiberglass
which would make the decks spongy.

When conditions are right, rot can move with incredible speed, up to 3/8
inch per day. The rest of the time, it goes into spores and lies dormant.
Moisture gradients and areas where the conditions get wet and then dry out
create zones where conditions are perfect. An unbedded fitting where the
core is wet and then fades out to dry is such a place. Having new rain
water coming in at the leak, along with spores blowing in the wind, and then
drying out slightly also can take the wood through optimum conditions.
Getting the deck sealed up so everything is stable might therefore stop or
significantly slow the degredation even if water is present. However, if
the moisture range is just right and stabilized, the whole core could go
quickly.

I wouldn't just rebed hardware but open up the mounting holes a bit and use
the trick of an "L" shaped rod chucked into a drill to rip out as much core
as possible. This will remove the stuff most likely to contain spores and
aid drying. Suck out the sawdust with a strong vacuum and pour in an epoxy
with good penetrating power after drying as long as possible. Replacing the
core with solid epoxy between the laminations will strengthen the fittings
and tie the skins together in a way that will help strains prevent
separation of glass and core.

On the bright side, the upper skin of the deck in a boat of your age is
probably as thick as the deck of an uncored boat would be if built today.
Even if some rot and a bit of deck flexing are present or do develop, she
will still be strong enough for anything you want to do with her except get
you purchase price back.

--
Roger Long