The movement associated with a keel may still be more than wanted. for two mini keels it would be significantly less.
--- In harryproa@yahoogroups.com.au, "Peter Southwood" <peter.southwood@...> wrote:
>
> Note that the CofE for the hull shifts radically during a shunt, but for a keel it moves far less
> Cheers,
> P
> ----- Original Message -----
> From: JT
> To: harryproa@yahoogroups.com.au
> Sent: Saturday, June 19, 2010 5:03 AM
> Subject: [harryproa] Re: Rudder lift?
>
>
>
> Gardner,
>
> Having fun, eh ? Yes always better to engineer it right, and we get to decide which trade-offs to accept. Rob said it on a post long ago and I believe his experience, we generally need about 2% of sail area for leeway management and directional control. (+/- somewhat). Given that minikeels get you to the same place as a daggerboard just a little higher form drag which mostly effects slow speed.
>
> I like 'em better since they are generally more robust, to take a licking and gives the LW hull something to sit on if beached for hull cleaning. Makes the whole boat sit a little more level on the dry.
>
> The other point is the reality the CE for pivot is moving fore/aft depending on point of sail. Versus the two separate daggerboards, a longer minikeel may be as good or better for rudder control. With better helm control, if we could retract the fore rudder then drag losses may be no worse than original intent from the two large rudders.
>
> JT
>
> --- In harryproa@yahoogroups.com.au, Gardner Pomper <gardner@> wrote:
> >
> > I am wondering if there is a way to predict the effect of a mini-keel. In my
> > sidecar clone I am designing, my lw hull has excess bouyancy, so the draft
> > will generally be around 6" when I am not really pressing the boat hard. I
> > am willing to have up to a 2' draft, so I could potentially stick an 18"
> > mini-keel under it, if it would help the rudders.
> >
> > I could go 2 ways with that mini-keel; I could have it a high aspect ratio,
> > and have it only 6" wide, or I could go for a decent surface area, and have
> > it 3 feet wide. The smaller one would have less drag, and would break off
> > easier if hit, but would it actually help?
> >
> > - Gardner
> >
>
>
>
>
>
>
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