rhys wrote:
On Wed, 26 Apr 2006 22:53:17 -0700, Evan Gatehouse
wrote:



I would bet $ that you have #2 situation. It's far more typical.

I concur. As you are getting far more extensive and experienced advice
than I could render, I leave you to what will be a messy job (but done
properly) with two comments.

1) Consider marine plywood but only if it is entirely encapsulated.
This means sealed, coated, encased ENTIRELY in an epoxy that will
repeal all water intrusion. I recommend it due to the ease of getting
it close to the right size and shape to replace the core you will
likely have to dig out. You can precut the inspection holes before you
glass it in, and you can adhere the wood to the inner skin with a
"mayonaisse" of epoxy and fibres or microballoons. You can carefully
take off the top "skin" and replace it later and paint the surface to
match.

2) Don Casey's books on hull and deck repair are excellent and easy to
follow. I recommend them. I also recommend talking to other people
who've done this work.

Good luck.

R.

Thanks for pointing out the various advantage of using marine plywood
as core material. It is supposed to be more rigid than balsa core if I
understand this correctly.

Yes, I have the Don Casey's with me along with the Fiberglass Boat
Repair and Maintenance book from West System. They are great.

Jay Chan

big snip


I am not sure if situation #2 (not properly sealing caused the problem)
is really the cuase of the problem. I say this for two reasons:

1. The inspection hole that was not properly sealed is slightly
different from other inspection holes on the deck. The flange of this
one is slightly smaller than the others, and it has _round_ indents on
the cover (for our fingers to twist the cover open) instead of _square_
indents. This tells me that it is a replacement. The original one was
probably cracked. And I am speculating that the reason why it was
cracked might have something to do with the deck deflecting. The
ex-owner didn't seal the replacement properly (not enough sealant and
is missing one screw), and this caused more problem; but that seems to
be the secondary source of the problem.

2. The fiberglass skin is very thin. The combined thickness of the
deck is only 1/2" with 3/8" is the balsa core; in other words, the
thickness of both skins combined is only 0.125". I have a feeling that
this is very thin.

Seem like many newsgroup members have suggested that 3/8" balsa core
should be strong enough to support 35" span as long as it is sandwiched
with proper fiberglass skins. This leads me to wonder if the thin
fiberglass skin is considered as proper, and I am also wondering how
much fiberglass each skin really has -- may be most of it is just
gelcoat. Of course, I don't have enough experience to judge if this is
thick enough. Hopefully, someone can share his experience in this
area. Thanks.

Jay Chan

Hi Jay,

The proper thickness of fiberglass is whatever the designer decided upon.

Creating a stiff structure is relatively easy.

Creating a LIGHT WEIGHT stiff structure is another matter entirely.

Having said all that, yes, the glass skins do seem rather on the light side.

But whether that is is a good thing or a bad thing has to be judged in
light of the intended use of the thing.

Overweight racers don't win many races.

There is no reason that the deck can not be repaired - other than
what the job will cost.

If the core is wet, the cost just jumped.

How much of the core is wet?
ie: How extensive is the penetration?

I'd suspect it goes deeper than you have noticed so far.
Bummer, huh?

So it's a question of how much it's worth to you to fix this thing
and what you want it to look like afterwards...



I don't think I caught the type of boat you are dealing with.
That might be helpful.

Posting some photos somewhere might help too, since I'm
still running under CrystalBall 1.0?

Richard

Richard Lamb wrote:
big snip


I am not sure if situation #2 (not properly sealing caused the problem)
is really the cuase of the problem. I say this for two reasons:

1. The inspection hole that was not properly sealed is slightly
different from other inspection holes on the deck. The flange of this
one is slightly smaller than the others, and it has _round_ indents on
the cover (for our fingers to twist the cover open) instead of _square_
indents. This tells me that it is a replacement. The original one was
probably cracked. And I am speculating that the reason why it was
cracked might have something to do with the deck deflecting. The
ex-owner didn't seal the replacement properly (not enough sealant and
is missing one screw), and this caused more problem; but that seems to
be the secondary source of the problem.

2. The fiberglass skin is very thin. The combined thickness of the
deck is only 1/2" with 3/8" is the balsa core; in other words, the
thickness of both skins combined is only 0.125". I have a feeling that
this is very thin.

Seem like many newsgroup members have suggested that 3/8" balsa core
should be strong enough to support 35" span as long as it is sandwiched
with proper fiberglass skins. This leads me to wonder if the thin
fiberglass skin is considered as proper, and I am also wondering how
much fiberglass each skin really has -- may be most of it is just
gelcoat. Of course, I don't have enough experience to judge if this is
thick enough. Hopefully, someone can share his experience in this
area. Thanks.

Jay Chan

Hi Jay,

The proper thickness of fiberglass is whatever the designer decided upon.

Creating a stiff structure is relatively easy.

Creating a LIGHT WEIGHT stiff structure is another matter entirely.

Having said all that, yes, the glass skins do seem rather on the light side.

But whether that is is a good thing or a bad thing has to be judged in
light of the intended use of the thing.

Overweight racers don't win many races.

There is no reason that the deck can not be repaired - other than
what the job will cost.

If the core is wet, the cost just jumped.

How much of the core is wet?
ie: How extensive is the penetration?

I'd suspect it goes deeper than you have noticed so far.
Bummer, huh?

So it's a question of how much it's worth to you to fix this thing
and what you want it to look like afterwards...



I don't think I caught the type of boat you are dealing with.
That might be helpful.

Posting some photos somewhere might help too, since I'm
still running under CrystalBall 1.0?

Richard

Mine is a 18-ft center console. I use it strictly for fishing.
Therefore, being light weight and running fast is really not an issue
to me. I surely like the repair to look good if I am going to spend
time and money in fixing it; but the main purpose is to get the problem
under control and not getting worse, and I definitely don't want to see
the same problem to reoccur after I have fixed it.

Yes, I surely feel that the fiberglass skin seems to be quite thin.
Thanks for confirming this to me.

I don't think the core is still wet. But the balsa core material
around the inspection hole is really rotten away. Pretty soon I will
find out how bad the situation is when I lift the fiberglass skin in
this weekend.

You can see the exterior look of the boat in this link (large picture
alert):
http://www.geocities.com/jaykchan/boat.html
Unfortunately, I don't have a picture of the deck area.

Jay Chan