[MHml] Weather helm at speed

[nudd]

Bill Gibbs wrote:       Reply to:   Re: [MHml] Weather helm at speed
Paul Nudd should have experience.  Raw Nerve and the other Crowther South Ocean 50 (Rotengu???  I'm sure the spelling is wrong, I can't even pronounce it, let alone remember it) both use a daggerboard in cylinder setup.
Bill Gibbs
Sonrisa/Afterburner
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Rontigu I think! The incredible friction in the bearings on the rotating drum/trunk made it impossible to tell if there was weather helm olr lee helm. I needed both hands on the tiller and most of my strength to move them
at all. They stayed where you put them. I think they have fixed the problem now. I have not been aboard Rontigu and not aboard Raw Nerve since repairs.
P.N.
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Tony Hammer wrote:
Crowther's newer big cats (eg Ed Wheatley's 50 footer abuilding but won't be ready this year he tells me) have the VERY high aspect ratio daggerboard in a cylindrical rotating trunk.  Two problems I see here:  1.  A 9 in
wide rudder, even if 6 ft deep in the water, is not going to make slow speed manoevering easy.
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Worse than not easy - non existant. To manoevre at low speed use the engines, forget the rudders. The rudders work fine when there is flow over them so they work as foils.
For example, stopped in irons through a tack - simple, just back the sails & sail backwards, reverse the helm and swing round tobeam on to the wind. With big wide rudders this works fine. With very narrow rudders reversing
the helm has no effect. You just keep sailing straight backwards. If you keep the helm straight when you are going backwards fast enough you can put on a little bit of helm and get the boat to swing around to beam on. Then
if you sheet in the main you go straight back up into the wind - helm wont stop it.. If you have a big enough jib you can sheet that in and leave the main loose until going fast enough to steer.
Narrow rudders are fine as long as you don't stop. In very light wind you just have to start the motor(s) or paddle (don't bother trying to skull the boat along with the rudders).

Paul Nudd
Sydney Australia
Lock Crowther D#72 38'Cat XL2
nudd at ozemail.com.au
www.come.to/Multihulls-Offshore