Research=Confusion

[wet-willy]

I've been hunting around for info on what to use to refinish the hull of my 18' Peterborough runabout.It seems to be done up in some type of varnish,deck to keel(no visible glass mesh lines).It's quite thick and in good shape.But there are a few rot spots on the stem and the keel.So I'll have to re-do it.

In my search,I've found many different epoxy based paints and sealers,which is good if I want to color the hull,which I'd rather not.but all the varnishes i've found sofar make the statement"Above the waterline use only".

Is there a hull varnish that will work below the waterline and be durable enough for repeated trailer launch and loads?

[wet-willy]

Hmm.61 views and no responses.Guess no such varnish exists.

[P.L.Lenihan]

I'm no expert on any of this but, every "classic"Chris-Craft,HackerCraft etc etc that I've ever seen usually is varnished down to the waterline,which is usually painted all the way around to the other side.That is, there is bottom paint or anti-fouling applied to the bottom.The only exception to this has been with canoes and some other refined rowboats like St.Lawrence skiffs etc which see relatively little time in the water compared to their time spent in storage and can be manhandled up to a roof rack or custom carpet lined trailer bunks.Alot of these too,if built new or renovated end up with some sort of epoxy treatment first which is then covered with a good quality varnish loaded with UV inhibitors.None of them sit in water very long.

Hopefully you'll get some better informed and helpful info soon.

Peter

[mcdenny]

The above the waterline products will be fine for the whole boat if it is kept on a trailer. Beware the area of the bottom that touches carpeted bunks. The carpet can stay wet for a long time and affect the paint.

Regular topsides paint like Interlux Britesides says not to use below the waterline too but lots of people do on boats that are not left in the water 24/7. My boat hangs in a hoist in the summer and sits on a carpeted bunk trailer outside in the winter and the Brightsides bottom paint is still good after 7 years.

BTW, the rot spots sound like a much bigger problem than the varnish.

[Peter Malcolm Jardine]

The two part varnishes will survive below the waterline...

[wet-willy]

SUPER!Thanks for the info,guys.I was really hopeing to keep the all wood look.Full varnish it is.I assume the 2 part varnishes are more durable than the 1 part.

I'm all over the rot problem.Been looking into what woods to use to replace badly damaged parts as well as something called CPES.(Clear Penetrating epoxy Sealer)It's a bit pricey,but the longer the finish lasts the better.

[Lew Barrett]

SUPER!Thanks for the info,guys.I was really hopeing to keep the all wood look.Full varnish it is.I assume the 2 part varnishes are more durable than the 1 part.


Not necessarily, and I'd guess all of them will wear/scratch out with alarming speed when getting the boat on and off a trailer. Different formulations are good for different tasks. The two parts are harder, and as Peter suggests may be better suited to this unusual application, but they are generally more brittle as well. If you have significant expansion and contraction as the boat dries and is re-launched, the finish will crack and peel at the junctions as the plank seams move. I suspect there is a reason we rarely see varnished bottoms on carvel planked hulls, but your experiment is encouraged and will be watched with interest, I'm sure.