Mast stiffness on a multihull vs mono

[thims]

Is there a significant difference between mono-hulled and multi-hulled masts? Is mast specifying an experts domain? Or can I just replace mine with any mast of appropriate length?

[David M]

With everything else being equal meaning displacement, sail area, etc, catamaran masts are beefier because the initial righting moment of a catamaran is greater than the initial righting moment of a monohull. The loading on the sail is directly proportional to righting moment. Loading on the sails then has to be transmitted to the hull via the spars and rigging.

Naval architects determine the scantlings of the spars and mast. Replacing your mast "with any mast" is not advisable without consulting a naval architect or someone who is very familiar with doing this.

[thims]

So do I need a naval architect to specify a new mast?

[Joli]

No......

You need a spar maker. They know what section to use and how long an unsupported panel can be.

Ever wonder why multi's have diamonds and most monos don't? It's how you support the panels.

[David M]

Originally Posted by thims

So do I need a naval architect to specify a new mast?

Not necessarily, you need to consult with someone who is very knowledgeable about replacing masts or the boats manufacturer. You definitely need to find out if your new mast is the equivalent or the better of your old mast. If you cant find a naval architect then you may try your boat yard manager or even a really good rigger. I second Joli's idea as well.