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Bent Top and Radial Sections - Why are they illegal?

Andy B

Having just had to write off a Radial Bottom section after a very bad death roll I realised I don't actually know why bent sections are illegal. Is it they just do not comply with the rules, or, is there really a performance advantage to be had from using a bent spars?

Your thoughts would be appreciated.


There can be an advantage in lighter airs. Both the standard and radial sails have a lot of their shape induced by the amount of luff curve in the sail. To have the mast bend and "fit" the luff curve properly, we have to use mainsheet and/or vang tension, both of which are also tightening the leech. In lighter air, this is not ideal. Ideally you would want a leech with more twist (loose, not tight). So if you can "pre-bend" your spars, you don't need a lot of sheet or vang to have the mast fit the luff curve.


Well-Known Member
This has sometimes puzzled me, too. How come an old crappy mast is illegal exactly because it is crappy, taking a permanent bend every time you pull the sheet or the vang?

But as 49208 said, a pre-bent mast might be marginally beneficial in some marginal conditions. If it was legal, it would lead to tuning guides giving certain mast bend numbers for certain wind ranges, and to insane amounts of nearly-useless last-minute bending and bend measuring in the boat parks of the world. I can even imagine some specialized (and expensive) mast-bending equipment getting developed.

Seems pretty smart to not go down that road.

Andy B

Many thanks, I can see with the reduced leach tension bent sections might be faster in light and strong winds and probably slower in medium winds. The bottom line seems to be it's much better to have boats which are exactly matched and its all down to the sailor on the water rather than boat park tuning.

Lets hope the composite top section, if it is ever released, solves the problem of the top mast. I'm not aware of any proposed solutions for the Radial Section and may be its something we have to live with.
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