Cracking plywood sounds!

[Corrib]

I started the plywood planking on my Hartley TS21. When I started rough fitting the first bow piece (bottom section) using clamps to pull the ply into position I could hear small cracking sounds. I probably need steam or hot water to make this piece fit because of all the hard curves the ply needs to follow.
Whats the best way of doing this? my worry is, on final fitting, how will wet plywood affect the epoxy glue up between the plywood to stem ,keel and chines etc if water gets in there?
Many thanks for any suggestions Ideas

Regards

Kevin

[Billy Bones]

A UK mag, Watercraft, I think, is running a series of articles on building the plywood Cape Henry 21 which has some serious curvature at the stem. They used a wallpaper steamer to bend a damp plank to conform. They may have kerfed the inside as well. At any rate, when the steam was removed and the plank dried out it retained the shape of the bend and was easily hung.

Good luck.

[JimJ]

Kevin

What plywood are you using?

Wood type?
Number of plys?
Are the plys all the same thickness?

Jim

[Leon Steyns]

Hello Kevin,

If this is an option (check with the designer!), you might want to 'laminate' two thinner layers of ply together. Thinner ply sheets (say, 5mm) bend easier than thicker ply sheets (say, 10mm).

But first, consult the designer! Usually, cheaper plywood has more voids (despite BS1088 and all that) and will be more difficult to work with.

http://www.boatplans.co.uk/images/21e.jpg

Greets, Leon Steyns.

PS - Did I tell you to check with the designer? :D ;)

[ 06-19-2005, 01:33 PM: Message edited by: Leon Steyns ]

[Bill Perkins]

With the piece clamped as far as it will go drap it with heavy towels and pour on as much boiling water as the towels will hold . This worked well for a friend of mine .

[Corrib]

Jim I'm using a 9mm (3/8) 5ply (BS 1088) marine good quality stuff (I think). The two outer plys are thinner than the inner ones.

[DougWilde]

Kevin,

You do all your wet torture, let the wood dry, then attach to your boat.

Take a look at my planking of Williwaw, at 15'6" not quite your size, but the technique is the same. It has a bit of nasty twist right at the bow. It is near the bottom of the page.

Planking of Williwaw (http://dbwilde.home.comcast.net/Williwaw/planking.html)

Doug Wilde

[WayGray]

I agree with Doug. Had the same situation with the boat I am building. I built a shallow basin about 4" deep by 3' by 20' using lumber laid in a long rectangle on our patio to form the walls and then covered with a plastic sheet. Filled the center with water and put in the plywood plank for a couple hours. Put bricks on top to keep it submerged and turned it over once to get rid of bubbles and make sure that both sides were saturated. When I took the plank out, flexibility was significantly improved. I had previously tried applying wet rags and heat, but this worked better, especially on such a large surface. Once the wet plank was clamped in place, I left it until it dried out (couple days). You could also add heat or steam while clamping. Then removed it, did the final fitting, and went back with screws, clamps and adhesive to really secure it in place. Then repeated the whole process with a second layer of 6mm plywood to get the 12mm total thickness I desired. Good luck.

[ 06-20-2005, 10:32 PM: Message edited by: WayGray ]