Seeking a textbook on multihull structural forces

[nacrajon]

I thinking about replacing the beams on my 21 ft demountable tri to gain a wider beam and more righting moment.

Is there a reference text around that I could buy as I want to double check my structural calcs and ensure my assumptions are correct.

Any recommendations?

 

[TANSL]

See what they say about this issue any Classification Society regulations or the ISO 12215 standard.

 

[oldsailor7]

I thinking about replacing the beams on my 21 ft demountable tri to gain a wider beam and more righting moment.

Is there a reference text around that I could buy as I want to double check my structural calcs and ensure my assumptions are correct.

Any recommendations?

What do your existing beams, (Akas), look like.?

 

[nacrajon]

Boat is a Virus Magnum 21 classic, I want to convert it to S spec. Beam would change from 4m to 4.8m. Demountable tri, alloy mast extrusion with 81mm ID across the main hull. Cross beams slide in with 80mm OD and from memory 2mm wall thickness.
I can only get 5000 series 80mm tubing in Australia or go carbon at significant expense. There is approximately 0.5m that is telescoped and held in place with a retaining pin. Floats are clamped with a saddle.

I've got a non standard 22m gennaker and longer rudder and improved centre board.

This boat has been in the Bass Straight for the last two weekends sailing so I'm looking for reliability, not ultimate light weight.

Manufacturer has gone bust so I can't buy the parts over the counter, I will reverse engineer it.

 

[Alik]

Well ,You have to re-calculate the rig as well. It is not likely to be designed for increased righting moment. So, You would need a book on rig design as well

 

[Richard Woods]

Waterstays?

Richard Woods

 

[cmckesson]

Classification Rules

I have a chapter in my book (http://www.amazon.ca/Practical-Design-Advanced-Marine-Vehicles/dp/1497396891 ) but mostly it amounts to an invocation of the DNV Rules. You could skip the book and go straight to the classification society, or you could use the book to help orient yourself and interpret what the rules are saying.