Wood/Epoxy Keel and Keelson

[Asleep Helmsman]

I'm on the run now, I just got my CNC mill running again, had to come back and get the manuals; I'll start a thread on this later.

I was thinking maybe you should ruff up the maple with 40 grit paper at the bonds and make sure and use the high density filler, and don't for get the fillets on both sides of the bond. This may be redundant, as you might already be doing that.

By the way I think maple will resist fracture better than oak, mostly because oak is so prone to grain run off.

Good Job,

Joe

[rwatson]

I am wondering if all this testing is really going to tell you anything usefull.

Sure, you can wreck a few blocks off wood under intense pressure, but how would you get that kind of pressure in a large keel section?

I am thinking that if you were testing house foundations, you could easily smash a test lump of concrete, but those foundations are overengineered by several hundred percent.

Especially in a keel situation, where you can load on the weight in many designs, you could overengineer like crazy and all this intense small sample tests really wouldnt apply.

maybe the design you are going to build isnt going to need such high structural loads.

[CanuckGuy]

Originally Posted by rwatson

I am wondering if all this testing is really going to tell you anything usefull.

Not to get philosophic on you, but curiosity is human nature. If I'm going to build a boat that will hold my life out of wood whose behaviour I don't know, performing these tests is crucial.

This test did show me that as far as nominal conditions are concerned, Maple is strong enough that I don't feel worried in my gut about it. However, it didn't show about conditions outside of nominal. Specifically decay rates while insulated in epoxy and fatigue behaviour.

[rwatson]

Like the Gougen Bros state - decay needs 1) Light,2) Moisture, 3) Oxygen.

If your timber is below say 12% in moisture when epoxied, the epoxy is solid, and you paint the stuff - no decay.

Curiosity is an admirable quality - as is self preservation.

I think the only way to really satisy both is to buld a full size keel of the sort of boat you want to build, suspend it on both ends, and then hang a few drums of water equal to the hull volume when flooded, from the beam.

If it doesnt break - you have a winner. Its not too dissimilar to the test they do for lifeboats - fill them with water and drop them onto water from 30 ft.

[fcfc]

Have you considered plywood for web ?

From your drawings, the brown wood part experiences shear. For this, the best wood is plywood, fiber at +45° - 45 °.

This is the way some wooden aircraft wing beam are made.

The web is plywood +- 45°. yes it is painful, because it makes a lot of waste in the sheet. The web is full heigh of the beam, and the flange is 2 part laminated wood bonded on each side of the web. The flange is not one part bonded on top of the web because it does not make a big enough bonding surface.

Now, this may be adapted to marine use.