[MHml] Ventilation of surface piercing daggers.

[Bill Gibbs]

If we're talking about rudders, we have all the helm balance, and rudder
mechanics (tip flutter and torsion loads among them) issues to consider,
when raking.  Then there is kelp.

 

Bill

Afterburner

 

From: multihulls-bounces at steamradio.com
[mailto:multihulls-bounces at steamradio.com] On Behalf Of Roy Mills
Sent: Thursday, December 27, 2007 9:54 AM
To: Informed discussion of multihull issues
Subject: [MHml] Ventilation of surface piercing daggers.

 

I was discussing this with a friend who thought he remembered Malcolm
Tennant having once said that inclining a surface piercing foil forwards by
7 or more degrees would stop ventilation. I did not rexcall it, but thinking
about it one can visualise that a forward raked foil would tend to have
water rushing up its forward surfaces, and if water was rushing up could air
fight its way down????

 

    Did Kelsall have significant problems or not when he  used one many
years ago? I know that the Cherokee cruiser from Sailcraft had one but it
was very much a cruiser so perhaps it did not matter.

 

        It does not seem to worry very fast trimarans flying the hull, but
they are relying then on a curved foil to leeward for both lift and leeway
resistance.

 

    Comments, experience or advice on this topic would be appreciated.

 

        Roy Mills 

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