Tiki 21 Aluminium cross beams.

[Tom Venning]

I have been building my Tiki 21 for too many years. I started with plenty of time and no cash... now I have the opposite. If I need to make the beams I may never finish the boat! So ....

Aluminum Cross Breams ... What standard cross section is best, and what dimension?

Looking forward to any advice, ideas, opinions and experience!

Tom

[Tom Venning]

Laurent ... many thanks for the clear answer ... I hope to have this done by next European Summer ... so will report back by then. Tom 

[Brian Paterson]

Tom,
what did you decide in the end? Will a 100mm x 100mm box section of 5mm wall thickness be up to supporting the mast?

I've just finished my T21 build. My last job was trimming the FWD beam tips, when I discovered that two feet of the bottom flange had rotted under the glass. No external signs - lucky I found it really.

Only took a few hours to fix, cutting back the rot, glueing and glassing a new piece in place. But it has made me a bit nervous. Im considering swapping to aluminum beams. I have a stainless steel mast tabernacle that can just bolt on. Easy.

Box section would be easiest, and strongest, I think. And available off-the-shelf.

I would appreciate knowing what you've found in your research. And what you decided.

Cheers

[Andrey Georgiev]

Hi Tom

I think you have to follow the original project :-) 

[Tom Venning]

Brian

No decision yet ... I intend to start the final stage of research before the European spring starts... no boat building before then ... however as I move forward I will be sure to give a full account.

Tom

Brian Paterson said:

Tom,
what did you decide in the end? Will a 100mm x 100mm box section of 5mm wall thickness be up to supporting the mast?

I've just finished my T21 build. My last job was trimming the FWD beam tips, when I discovered that two feet of the bottom flange had rotted under the glass. No external signs - lucky I found it really.

Only took a few hours to fix, cutting back the rot, glueing and glassing a new piece in place. But it has made me a bit nervous. Im considering swapping to aluminum beams. I have a stainless steel mast tabernacle that can just bolt on. Easy.

Box section would be easiest, and strongest, I think. And available off-the-shelf.

I would appreciate knowing what you've found in your research. And what you decided.

Cheers

[Tom Venning]

Andrey

Thanks for the comment ... however I really don't see myself finishing the boat if I go through with the original plans... my life is so full of so many other wonderful projects I need to reduce, reduce, reduce ... and finished beams and mast seem like a wonderful way of doing just that.

Tom

Andrey Georgiev said:

Hi Tom

I think you have to follow the original project :-) 

[Tom Venning]

Finally I have come to a decision about the cross beams... Not aluminum. Why? Aluminum bends differently to the original beams which will cause lots of different stresses on the boat that are not planned. Secondly the most easily available cross sections may be too weak for the boat. I am sure there are beams out there that are strong enough, but they are not easy to find. They also need to be for the marine environment, so not standard building material that makes them more expensive. 

I spoke to the designers at Wharram and they strongly advised against aluminum. At a push I could use the material at the bow and stern cross beams, but not the beam carrying the mast. To save building time they suggested replacing the epoxy fillets on the original plan with triangle wood glued into the same space as the fillet. This makes sense to me ... so I'm going to follow the plans with that minor adjustment.

Looking forward to getting my boat on the water ... hopefully this century! :-)

Tom

[paul anderson]

Tom,I do not think the mast beam is a  structure that you should be looking at making short cuts at all.Look for time saving techniques on less critical areas imho.

[Tom Venning]

I agree!