[Rhodes22-list] Gel Coat Cracks

[Graham Stewart]

Ron:
This must be very disturbing. It seems very strange that a boat of that age
would develop cracks now just because you were in rough seas. I assume this
was not the first time the boat had seen bad weather and from your
description it was rough but not a hurricane.

I would suggest that you have it examined by a pro to determine why this
happened. If there is something developing under the skin then patching the
cracks will likely go on forever and when fixed they will probably reappear.
The cracks in turn - if they extend deeper than the gelcoat - can lead to
water entry and that is not good.

The easiest fix, although probably temporary, is to apply gel coat crack
penetrating sealer. It is a thin white liquid that comes in a small squeeze
bottle.  It is supposed to be drawn into the cracks and seal them. I can't
say how effective it is but the idea of sealing the cracks at least
temporarily while you consider your options would be attractive and an easy
thing to do. If the cracks do not reappear it might suffice.

My concern would be to determine if the core has delaminated thereby
weakening the structure that supports and strengthens the skin. Does the
deck flex when you stand on it near the cracks - or anywhere else that is
cored? Is it only cored areas that developed cracks when you were out in bad
weather? If so, the fix may be more than cosmetic - not that cosmetic fixes
are easy either. I don't want to alarm you but it is the only reason that I
can think of to explain why this would occur now and so suddenly. 

My boat Agile (1974) developed extensive delamination on the foredeck and
side decks. Standing on the foredeck it became apparent that the deck was
flexing more than reasonable and it felt soft. The side decks did not flex
noticeably because the area of the flat surface was too small but as it
turned out had delaminated as well.  Thankfully the cabin top was pretty
good except around the mast step where cracks formed, non-cored areas were
good as well except for spider web cracks around hardware holes. The "best"
fix for cracks is to grind out the area, apply layers of glass and then
finish the gel coat. If you have to do that in any areas with the non-skid
pattern than hiding the surgery requires skills that I can't even fathom.
Obviously it is a traumatic and desperate step to take a grinder to the deck
of the boat. However, it seems that the weakness of the skin is the reason
for the crack and if you can't get in behind the skin to reinforce the area
flexing will continue and nothing done to the surface gelcoat is likely to
last.

I had a marine surveyor go over my boat with a moisture meter and he told me
I had extensive rot in the core. He was wrong and his incorrect diagnosis
led to extreme measures that in the end were not necessary. I will never
thrust a moisture meter again or a surveyor who relies solely on one. As I
eventually determined, the only small area with rot was at the bow around
the air vent for the head. 

If you have a problem, I think that it is crucially important to know
whether the problem is rot or dry delamination of the plywood from the skin
and between the plys of the plywood core. Stan mentioned in his short
history on the changes to the construction that at some point he began to
seal the core with resin. It would be good to know if he began doing this
before your boat was built. The fix in the case of delamination is much
easier than if there is rot. With rot the wood core really needs to be
replaced. With delamination, injecting epoxy is quite feasible. 

If you suspect either, try looking at the core through any openings such as
might be available by removing hardware such as the water intake or holding
tank pump out deck fixtures, deck vents, etc. You might be able to see
delamination or feel rot using a probe of some sort in the hole. Tapping the
skin with a plastic tack hammer or the handle of a screwdriver might tell
you something but for me it didn't help perhaps because I didn't have a
trained ear. Still if you learn the sound of areas that you know are solid
and work out to the areas that you suspect you might be able to identify
suspect areas better. If it is rot it is most likely to occur around
hardware where water might have penetrated. If you remove a screw from deck
hardware you might be able to tell if the wood in the hole is punky by
probing with a dental pick.  If it is dry delamination it is more likely to
occur in large flat areas. Of course one does not preclude the other. 

In my case I tried to locate rot by drilling small holes up through the
liner in areas that I suspected were problematic because of the flex and
then examined the wood that was removed by the drill bit. It is a lot easier
to repair the holes in the liner than if they are in the deck.  Of course I
didn't find any rot, because it wasn't there,  and it never occurred to me
that I could have delamination without rot. I literally had to tear the deck
apart to find the problem. That turned out to be a hell of a job and
unnecessary had I known what I learned once I got to see the core. If I were
at this stage and doing this again, I would drill many more holes starting
near hardware and fanning from there if I found any rot. 

If dry delamination appears to be a problem, and if you decide to try to fix
it yourself by injecting epoxy into the core, let me know and I will tell
you what I did - good and bad - and what I would do differently if I had to
do it again. But I am certainly no pro - I just could not afford to hire one
and had to make it up as I went along. 

I hope the problem with the cracks does not come to that but it is not the
end of the world if it does.



Graham 



-----Original Message-----
From: rhodes22-list-bounces at rhodes22.org
[mailto:rhodes22-list-bounces at rhodes22.org] On Behalf Of butterchurn
Sent: June-06-13 10:18 PM
To: rhodes22-list at rhodes22.org
Subject: Re: [Rhodes22-list] Gel Coat Cracks

Oh the boat is a recycled 1991.



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