stopping a splitting plank

[guillemot]

Almost a year after purchasing the house, I was told today by SHMBO that I may return to work on the dory.

I have found that the sides of the centerboard trunk, which I was in the process of assembling, have split from the ends in. They are made of white pine fastened to vertical oak endposts. The splits start at screwholes where the pine planks are fastened to the oak and extend 8-12" toward the middle. How do I stop the splits from spreading? I seem to remember something about drilling, plugging, glueing, but the search thingy isn't working. Thanks in advance!

Jeff

[Bob Smalser]

Did you leave the project a long time unprimed and unpainted? I'm a bit surprised the small 10" or so expanse of pine would crack with the boat still under cover...they usually wait til they're out in the sun or the height of the August dry.

Whoever you heard that from would drill a half-inch hole right at the end of the crack....plug it with a dowel....then whittle a wedge to drive into the crack using glue. The idea is that a clean, drilled hole stops the crack.

Me, if I weren't too far along mortising the thwarts into the trunk, I'd think about remaking the trunk using more stable wood in a q- or rift-sawn flavor, because come winter, the expanding wood will likely crush the wedge and next summer it'll crack again as the wood shrinks.

That said....I suspect even flatsawn pine used in the 10-13% M/C range and painted immediately wouldn't've cracked on ya....so the repair you describe may or may not work once you get it all well-painted.

[ 05-28-2005, 06:59 PM: Message edited by: Bob Smalser ]

[guillemot]

Thanks Bob,

You hit on the situation exactly.

After glueing in the dowel, do you think it would be acceptable to fill the crack with epoxy thickened with sandable filler (i.e. microballoons) or microfibers? The void is only a hairline crack - maybe 1/32 at the wide end. I don't think it'd be practical to try inserting wood into it.

Thanks again.

Jeff

[Bob Smalser]

No epoxy except for the dowel.....here's where I pull out the 5200 used as a putty with no wooden wedge driven in there.

The crack will close and open a tad each season, and epoxy will likely make it worse.

[guillemot]

Excellent. Will do. Thanks again.

Jeff

[Bob Smalser]

Here's an example where I did something like your crack on purpose.

http://pic3.picturetrail.com/VOL12/1104763/3075025/37657562.jpg

The little 1950's Hartley above was well-built but had chintzy sliding plywood doors in plastic tracks beneath the seats. Besides reminding me of Bayliner's worst efforts, they weren't very functional as the doors ate up half the openings.

http://pic3.picturetrail.com/VOL12/1104763/3075025/55185218.jpg

I made proper bins with tiedowns inside instead. Problem was, the seat top was plywood, but the upper and lower rails framing the bin openings were old-growth Doug Fir, and the bottom rail was a structural part of the hull.

I didn't want to risk cracking either rail, so instead of letting plywood to fashion my bins, I used more Doug Fir epoxied in, knowing it would crack.

http://pic3.picturetrail.com/VOL12/1104763/4664832/58825186.jpg

When they cracked, I just buttered them up with 5200 and painted over it....you have to look hard to see it.

[ 05-29-2005, 07:05 AM: Message edited by: Bob Smalser ]

[guillemot]

So you deliberately used the cracks with 5200 like expansion joints in a bridge? How has it held up?

[Bob Smalser]

If it was brightwork, I'da cut an expansion joint right int he middle of my workpieces....but in that particular application fat at the ends and skinny in the middle, you risk both a visible expansion joint and a visible crack...but with paint and goop, the lines are so small and so ransom, they blend in with the boat.

Holding up fine....a little more goo with each paint job is all that's required.

[Cosmo Lengro]

;)

[ssor]

The same thing happens in six panel doors. The panels are supposed to "float" but the paint glues them to the rails and stiles and when they dry they split, then another painter comes along and putties the split with hard putty and paints the door. Come spring the panel swells and spreads the stiles, so the painter putties the gap between the rail and the stile. come winter the panel shrinks and splits----------