[MHml] New improved OBMW

[Dan Frenette]

At 90' or so adding an additional foot or so under the water isn't going 
to change the effective hull length to make much difference.  Most of 
the math I've read indicates the hull crosses the wave troffs at about 
36' or so.  If that is true than the difference between a 70' and a 90' 
hull would only be a mater of the hull beam to length ratio being better 
on the longer boat.

Reducing pitching is a major deal in a race as pitching is drag on the 
hull and the sail plan.

I'm thinking the shorter stern is because a cat needs the flotation 
foreword when you drive it really hard off the wind.  Yes you can fly on 
1 hull but this isn't going to be a 100% on 1 hull and it's the rest of 
the time stuff that makes or breaks you.

It maybe that if you can stiffen the boat without adding weight aka with 
a center pod than a cat in this size range could actually be faster.  
But at that point is it a cat or a tri or does anyone actually care?

Dan Frenette

On 07/07/09 12:55, Bill Gibbs wrote:
>
> Reduced pitching?
>
>  
>
> *From:* multihulls-bounces at steamradio.com 
> [mailto:multihulls-bounces at steamradio.com] *On Behalf Of *Roy Mills
> *Sent:* Tuesday, July 07, 2009 12:46 PM
> *To:* Informed discussion of multihull issues
> *Subject:* Re: [MHml] New improved OBMW
>
>  
>
> BMWO is a tri, it does not just resemble one. At rest, and at low 
> speed it's hull is in the water. It is interesting that they have 
> lightened it by shortening the stern, and reduced wetted surface by 
> removing the central rudder. I find myself interested in the wave 
> piercing bows now manifesting themselves everywhere. I gather that 
> they have, or are felt to have, less drag than, presumeably, plumb 
> bows but I have not seen any what might be called scientific proof and 
> reasons to verify that. Obviously there must be some or CZ would not 
> have them and DZ would not have changed to them. I wondered if they 
> were not a sneaky way of getting a longer hull for a fixed waterline 
> length, the foward underwater projection not counting, but surely the 
> best way to do that is via a long overhang just above the waterline 
> which comes into play when the hull sinks down as it bears all the 
> weight when everything else is heeled above the surface.  So it must 
> be some other reason.  Details anybody?
>
>  
>
>         Roy Mills
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> Alter your subscription details or unsubscribe at the bottom of this page:
> http://www.steamradio.com/mailman/listinfo/multihulls
>
> Multihulls mailing list      (Multihulls at steamradio.com)
>
>   

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://steamradio.com/pipermail/multihulls/attachments/20090707/e4c3a948/attachment.htm