Checking

[Leon m]

My oldest son (age 10) has shown a serious
interest in learning to sail this summer.So
I bought a 14' wooden sunfish built around
1965 it is in very good condition except for
some checking,mainly on the deck and minor on
hull.I would like to keep it long enough for
his younger brother(age 4) to use too.so I
want to fix it right!The plywood has been
painted white I have yet to determine what
kind of ply it is.I also know it has been
stored in the rafters of a (dry)woodshop for
at least three years.The checking is very thin
and I was wondering if I used a good two part
epoxy paint if that would do the trick?or do
I need to glass it? I havent a clue.Maybe you
guys can help me out?
Thanks!...Leon M

[imported_Conrad]

Hi Leon- if it was me I'd just sand it down a bit to clean up the surface, then repaint with enamel. It has survived more than 35 years without glass or fancy paint chemistry, so why complicate things now? Checking doesn't weaken the structure, it just disrupts the quality of the finish. True, you might have to repaint again in a couple of years, but if the boat is being used on a regular basis and getting normal wear and tear, you'ld probably want to clean it up again anyway. ;)

Soft, semi elastic paints like any good quality exterior enamel probably survive the checking process better than a more brittle acrylic or urethane, so in this case cheap is not only to your advantage financially, but but also the more durable solution. I hope you have a great time teaching and being with your boys! :D

[Chris Coose]

Leon,
I'm with Conrad on this one.
I have a plywood pram that is on a auto roof rack all sailing season. It was an older boat when I got it and I suppose the fir plywood is 3/8ths, 3-ply. After 4 years of this use it has begun leaking through the checks. The sun and the dark color paint have had their way with the plywood.

Paint it with a couple of coats and keep it out of the elements when not in use.

[NormMessinger]

Ah yes, checking. Same thing happened to my first MacGregor sailing canoe made from genuine high quality fir marine plywood. However I found that the checks need to be filled with something in order for the enamel to bridge the checks. Since I have two MacGregors this one has been stored away until I decide what to use to fill the cracks. I'm thinkin' unthickened epoxy which I have on hand. Otherwise I would probably use lacquer putty from the auto paint store. Anyway, I'm hoping all the checking that is going to occur has. Maybe I'll get to it this year....

--Norm

[Gary Bergman]

well, I've filled a bunch of checking cracks with Elmers, then sanded down before painting. seems to expand and contract o.k. with my enamel paint on my cabintop....it is a maintainance thing, afterall

[NormMessinger]

Ah so. Yes that should work, too. Maybe better.

--Norm

[Wild Wassa]

I certainly would give the checks and cracks maximum satutation of epoxy. They will need refilling, possibly a few times. Just when you think you have them beaten .... more. They are the start of dry rot. I also find that simple checks and cracks aren't simple.

If you are going to paint over exhisting paint, make sure your prep is spot on. Also if the quality of finish is important, allow good curing times for the epoxy. I think a good curing time is about 4 weeks. No less.

Warren.

ps, Enamel is the class act but polyurethane is 'the' surface. If you can not see your face reflected in the hull's surface ... you could be a vampire.

[ 12-15-2002, 01:20 PM: Message edited by: Wild Wassa ]

[Dave Fleming]

Checking is the bane of Rotary Cut Doug Fir plywood. It has historically been a problem with the stuff. That is why eons ago, Simpson Plywood came up with MDO ak Medium Density Overlay aka a greenish resin impregnated paper overlaid onto the face or both sides of the Marine Grade Plywood. It solved the checking very nicely for many a painted boat. Usually the cabin or pilot house sides. There are lower grades of the stuff called 'painters sign board', pretty good but might have some generous voids and questionable interior veneers. Gary has a good thing with the Elmers Wood Glue and then a good oil based enamel.
No reason really to go over to the googe side.
If there are no other problems with the ply why spend extra time and money fiddling with googe?

A savvy yard painter could and did deal with that checking problem with his own painting schedule ie: particular mixes per coat. Something like 30 or 40% enamel for first coat, light sanding, and then 50% second coat perhaps another bit stronger coat and then final coat which if memory serves was never full strength.
But, most yards would not take the time or didn't have a savvy painter and so would use primer and then a top coat or two and that was it. In those cases checking was sure to follow some time during the season.
Am I making sense here?

[Wild Wassa]

Dave, the process you described by the savvy yard painter, painters call 'fat over lean' or thick over thin.

It stops the upper layer of paint from cracking, due to the binder being drawn into the previous layer of paint. It's a 500 year old technique.

The increase in plasticizers in the modern day enamel paint may retard, the movement of binder. I just don't know, a point for the Chemist, or painters. I'm of the opinion that enamel rehydrates enamel ... or the binder does. Boats seem to have Plastic Enamel on them.

Warren.

ps, Oils ain't oils, Sol. ... Anon.

[ 12-15-2002, 01:48 PM: Message edited by: Wild Wassa ]

[Gary Bergman]

Don't get me wrong, I like my finishes to the nines, but see my face? never! I choose my paints by how well they 'gloss off', better for sailing mate...keep it simple,it ain't rocket science,or 'showboats' for that matter.

[Wild Wassa]

It ain't rocket science ... it is for me.

Warren.

ps, I use water based poly, :D . I work on wooden racing dinghies only. My Boss, Gary, wants AC quality surfaces on the hulls. So he gets them ... slowly. I'll mix a few grams if 5 micron hollow glass spheres today with the epoxy, this will be the 4th retouch after 3 fairings, prior to painting, which will require fairing between coats. Then we polish the hulls. We want extremely fine surface grain. This particular boat was badly checked and cracked. Stripping caused some checking.

Recreational needs can be different of course.

[ 12-15-2002, 03:22 PM: Message edited by: Wild Wassa ]

[Leon m]

THANKS GUYS !
Good stuff.

[WWheeler]

I had some checking in the ply deck of my Y-flyer, (scow design like a really big Sunfish). Given it's age, it's probably Doug fir ply.

Since there was some really serious gouges in places, I attempted to fill with expoxy. Then I tried epoxy with sawdust filler, that works better, but it's still hard to sand. Fairing filler (West system) + epoxy is much easier to sand. Then I painted over with a good quality 2 part epoxy paint.

So far the results are really good. (not finished yet.), but if you can get away with just paint, it will save a ton of work.