Wood for tiki crossbeam

[chororo]

Hi, I´ve had the plans for the tiki 21 for about 10 years ago. 
I can't make up my mind yet, so I am going through the plans again.
What kind of wood did you use for them beams (I recon tiki beams for the 26 and up are closed, instead of I beams). The plans specify it shouldn´t have knots larger than a pencil end.
Can you join (scarph?) 2 or more pieces of wood to get the desired lenght.

Thank you in advance for the help you can provide.
regards

[Lovako]

I dont have any knowledge of Tiki 21 beams as I built a Pahi 42ft.

Its a I-beam design and the wood I chose was 18mm Marine Ply and Balau wood.

Balau might not be the best but it is readily available and not endangered.

Construction was a triple 18mm ply I-piece with x3 Balau top and bottom planks with second top one wider to hang my centre-box on with safety pins.

Check pics.

[Lovako]

Here is a rough sketch of the beam.

[chororo]

Thanks for your input Lovako.
The tiki 21 beams are just an I beam, with the vertical component being 15mm plywood, and the horizontal (top and bottom) wood. I can´t source suitable wood in that lenght.
Did anyone scarph (join) two pieces of wood to the desired lenght?

[Lovako]

Thinking back what I did was to have the scarf joints at 60 degree angels, or greater but on opposite sides to each other. If im not mistaken James Wharram has a write-up some where on it.

Also, if you go to furniture factories they have a router tool that cuts a multi-W horisontaly or verticaly in the two planks which is glued into eachother. The 60 - 60+ degree joints might be stronger.

Hope it helped. - i will check my plans.

(A scarf joint, or scarph joint, is a method of joining two members end to end in woodworking)

[Lovako]

Here are photos of the "scarf" write-up on my plans.

Not much to go by but hope it will help a little.

[Lovako]

Pic_1

[Lovako]

Pic_2

[Lovako]

Pic_3

[Brad Ingram]

This is heresy, but we just all went to 100x100x4mm aluminum square tubing for beams on our three 21's at club. Fast and easy.......and no rot! One guy's Dad is a structural engineer and made a program up to test and see if they would be sufficient. A member here has had similar beams up in the North Sea for almost ten years with no issues. I have wooden beams too, but the aluminum is lighter, rot proof, and quick.