[C320-list] 7" Hull Blister

[Allan S Field]

Brian - Very doubtful it's a blister as the cause of these is water
migrating into the hull, mixing with polyester resin to form an acid, then
eating its way back out in the form of a blister.  The "problem" is that
these hulls are vinylester layup so we don't get the same water to acid
reaction.  Also, since this is above the waterline, a blister makes no sense
anyway.  There was a series of boats in the 400's that had blister problems
but 797 would not have been one of them.  What it sounds like to me is a
void between the hull and liner.  I would suggest calling Catalina and
discussing this with them and what they'd recommend as a fix.  Again, I just
don't think it is an actual blister. - Allan

-----Original Message-----
From: C320-list [mailto:c320-list-bounces at lists.catalina320.com] On Behalf
Of Amiraults Family
Sent: Wednesday, November 2, 2016 6:49 PM
To: c320-list at lists.catalina320.com
Subject: [C320-list] 7" Hull Blister

Group:

 

This was close-the-boat-for-winter-day. Thanks to the orientation of the
hull and position of sun in sky, I made first note of a hull gel coat
blister located just aft and above the exhaust port. It is round, 7" in
diameter, and certainly sounds out as a void. This area is above the
waterline and neither I nor the local fiberglass guy has an explanation for
why it would happen.

 

My guy feels the correct solution is to open, treat, close and re gel coat
the area. He doesn't want to do this because due to the weather in The Great
White North the amount of weather warm enough to do it can't be expected to
be available post haul out or pre launch. As an aside, the club cranes
cannot lift more than 5 tons and so they arrange for commercial cranes for
one day in the spring (early May) and one day in the fall (Nov 29 this year)
to move heavier boats and we place 80 hulls in one day. The blister location
is too far below the bulge of the hull and too close to the waterline to
work on from the water. So his solution is before launch in the spring he
will drill a small hole in the blister near the bottom and another near the
top and then inject epoxy into the bottom until it comes out the top. Touch
up the holes and you're done. His claim is that this will fill the void,
reconnect the gel coat to the hull, and be possible with the likely
available temperatures.

 

Does anyone have an insight into what may have caused the blister, and
whether the proposed solution is sound?

 

Brian Amirault

797 Waltzing Bear, too 



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