Subject: Re: [harryproa] Re: Design your proa
From: Rick Willoughby
Date: 5/16/2011, 7:30 PM
To: harryproa@yahoogroups.com.au
Reply-to:
harryproa@yahoogroups.com.au

 

Rudolf

I responded to a similar question from Gardner.

There is some potential for a shallow keel to improve the efficiency and control.  The best for performance is a high aspect cambered centreboard that can be raised and lowered.  There is a range of options between that and using the hull or ventilating rudders that might give a performance improvement with better control.   

To arrive at the best solution requires knowing current situation and preferred constraints such as maximum draft and fixed or elevating board.

Observations from the existing boat operation would also be helpful.  Things like the degree of helm under certain sailing conditions, an idea of leeway and boat balance.   These help in fine tuning a model that can be used to test different options.

Rick
On 17/05/2011, at 5:33 AM, Rudolf wrote:

 

Rick,
Does this mean that a hull with shallow keel could be as effective as
a hull with ventilating rudders?
That would make a shallow keel a good alternative.

Rudolf
--- In harryproa@yahoogroups.com.au, Rick Willoughby <rickwill@...> wrote:
>
> Rudolf
> There is performance merit in resisting leeway with a non-
> ventillating foil or foils. Once this is achieved it does not matter
> much how the boat is steered unless the rig is poorly balanced. I am
> now thinking dipping rudders a little more sophisticated than what
> Tarawa is using would be my starting point.
>
> The other conclusion is that a slab sided or very deep V (> 45
> degrees) hull will be as effective at resisting leeway as ventilating
> rudders. So a reasonably elegant solution is exactly what Tarawa has
> in concept. It could be engineered with a bit more precision.
>
> Rick
>

> >
> >
> >


Rick Willoughby
03 9796 2415
0419 104 821

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