Hull repair

[vegatern]

I think I may pull the boat and bring her home. She has been in the water continously for much too long and needs some serious work ( I've scraped the dock so often that fenders were long ago given up as an affectation). I want to remove some old throughhulls and glass over the hole, split the rudder open and inspect it, and maybe add a couple of stringers in the forepeak. I have a couple of gallons of polyester resin, but Don Casey in "Sailboat Hull and Deck Repair" says that I should use an epoxy resin because of its greater strength and bond. Is the difference signifficant enough that I should set what I have aside and purchase epoxy? I can't return what I have.
Craig TernV1519

 

[Whiskerpole]

Hi Craig

You can still do a good job with polyester resin as long as you use good
practices. Polyester resins bond strength relies on a mechanical bond much
more than epoxy which bonds at the molecular level.

Make sure the area to be bonded is free of all gel-coat/paint and
mechanically sanded with course grit sanding disks (24-40 grit) to create
good tooth for the bond. Areas should be built up alternating with glass
cloth and mat.

Epoxy repairs can be several times stronger, but in most cases repairs made
with polyester resins are more than adequate.

Regards

Bob Fuchs
Silentium
v 2296

 

[SVFlyAway]

I actually had a yard glass over one of my thruhull holes. The guy who did
it was the yard foreman and it is a big yard. He had been doing fiberglass
work for over 30 years.

He said to use only vinylester resin, not epoxy. What he did was first to
go inside the boat and glass in a piece of fiberglass roving -- grinding
off the surface coating and grime. Then he went out side and use a DA type
grinder and feathered the hole all all round, for 3 or 4 inches. Then he
started laying up a couple layers of mat and roving, building the size up
as the feathered hole expanded. The he finished off with cloth and then a
final coat of resin. Finally sanding with increasingly finer paper. Since a
hole under water isn't seen and is covered with thick bottom paint, one
doesn't have to go down to really fine paper.

I was quite impressed with this technique since feathering the hole makes
a plug (if you will) that is larger on the outside than the hole itself.
Hope that all makes sense.

He says to always use vinylester resin as it bonds well and has better
water resistance.