A/B DF marine plywood

[wadeg]

Having trouble finding AA marine doug fir ply locally and want to avoid selling organs to pay for wood shipping costs through the project. About the best I can find in the Portland area is A/B marine grade. Anyone know if it's a "no no" to settle for the A/B stuff?

[Kyle Boatright]

For what purpose? If we're talking non-structural floorboards, sure. If we're talking something structural, probably not...

[wadeg]

For ribs. 1/4" thick on a sailplane.

[WLIU]

The A-A and A-B refer to the quality of the face plies. A-A will come with fewer defects than A-B. You will need to lay out your parts to avoid any defects in the A-B grade material. So the down side is that you will waste more material. But that can be less expensive than paying for shipping. You should get a copy of the spec for the type of plywood that you are using. Should be online somewhere. The mil-spec for aircraft plywood should also be online somewhere. That information and some careful layout should allow you to use local materials to make the parts that you need.

Best of luck,

Wes

[Kyle Boatright]

I would verify that the spec for AB excludes voids. If so, you're talking a cosmetic difference on one side - B grade plywood can have more patches per side than A grade. I do not think a few more patches would be a problem for your application. That said, when you purchase the plywood, sort through the stack carefully to find flat sheets which have as few patches as possible. It is impossible to work with warped plywood. I had to scrap a 4'x8' sheet of aircraft grade Doug Fir once upon a time because it was badly warped. The supplier made good on it, but what a waste.

[Fliegen]

Similar or greater strength and similar weight can be had in 6mm, 5 ply meranti marine grade plywood. It is also more stable and higher quality than AA or AB doug fir that is currently available. In the Portland, OR area, Crosscut hardwoods lists Meranti as available with a tradename Hydrotek. Occoume plywood is also available. lighter weight and lower strength. You should look for a British standard 1088 product for high quality.

Wayne