Its not so much as just windward hull skimming the water, but more the load carried to windward knowing even when static windward hull is not needed to carry large amounts of weight with a sail design to improve forward drive, there is the difference. The power sources ability to over come heeling force along with hulls ability not to interfere with this. Rotational force from weight to windward handicap this compared to pacific styles when pushed to the limits.

Being able to instantly depower seems more about getting used to a different type of seamanship rather than being able to or not. The rig its self when tended to produce forward drive vs heeling moment in such instances enhancing safety factors by rig type efficiencies alone. When you start to slow is when you start to worry with a rig as described. The rig should feel like it constantly seeks the wind with what seems unlimited top end speed!!!

Todd

Seen the news report of the flooding IN THE DOWN UNDER!!!
Everyone here okay?

--- In harryproa@yahoogroups.com.au, Mike Crawford <mcrawf@...> wrote:
>
> Todd,
>
> One thing that might help the discussion is getting clear on some of
> basic criteria.
>
> You're right in that there's a lot to be said for the pacific proa
> design where you've got a lightly-loaded windward hull just skimming the
> water.
>
> There's an argument that the righting moment from a 60/40 windward
> hull will allow you to create enough drive to overcome the additional
> wetted surface area, but let's put that aside for a moment. I don't
> have the software to prove or disprove this position, so sor the sake of
> discussion, let's just assume the pacific proa is more efficient.
>
> If you don't mind continually manning the sheets and adjusting
> balance, the pacific proa is going to be a very fast and elegant sailing
> boat. I agree with you completely, or almost completely, in this
> instance. If you add a dynarig to the equation, you'll have a very
> sweet boat, as you've demonstrated with both your models and your
> full-size proa.
>
> ---
>
> But what if you can't continually balance the boat and adjust the
> sheets, or alternately, want the option of not having to do these things?
>
> This can happen on a full-day daysail if:
>
> 1. You hit a squall before getting back to land and need time to reef
> or furl the sail in very high winds and high seas. It actually is
> possible to unexpectedly get hit with huge winds that don't give you
> much warning, especially if the sky is not clear and there's no
> associated black-cloud thunderhead associated with the wind burst.
> People have gone from ten knots, to seventy knots, back to ten knots, in
> a span of a few minutes.
>
> 2. You need to eat, drink. or pee, but don't want to stow the sail.
>
> 3. You need to take multiple bearings with a sighting compass and
> locate yourself on a chart. This takes both hands, and sometimes has to
> be done repeatedly if you don't have a chartplotter, or if your
> chartplotter fails, and you're either in unfamiliar waters or in fog.
> It's not realistic to stow the sail every time you want to verify your
> location.
>
> 4. You become injured or seasick, and can't handle boat balance and
> sheets the way you could if you were in perfect condition.
>
> 5. You become incapacitated and a less-experienced guest has to pilot
> the boat (and/or furl the sail in high seas and winds).
>
> 7. You want to take out several people who have little or no sailing
> experience, and can't count on them to help with balancing the boat,
> particularly if some of them are not agile.
>
> 8. You've simply been at the controls too long, need to rest, and
> either let the boat do some of the sailing and/or have someone less
> expert than yourself take control.
>
> And while all of these *might* happen on a daysail, one or more
> eventually *will* happen when cruising.
>
> ---
>
> What then?
>
> I'd argue that these situations would call a proa with a sail that
> feathers into the wind, and completely depowers, without any input or
> control, when you release the sheets, and which carries a good amount of
> weight to windward in order to keep the boat upright when hit with gusts
> and waves at the same time.
>
> To me, the question is: how do we improve on the harryrpoa design
> given these criteria?
>
> It's not which design is the fastest, or most elegant, given a good
> captain and agile crew, but which design is fastest and safest once you
> add in the eight situations above.
>
> I don't think that Rob has solved everything, but having said that, I
> don't know how to improve upon what he has done. But with your
> experience and intuition, you might be able to find ways to do even better.
>
> So, what would you do to make things faster, more elegant, and/or
> safer for a lazy safety-conscious wimp like myself?
>
> And I mean that question, too. You design and build fast boats. If
> there's something faster/lighter/cheaper out there that takes care of
> the above criteria, I'm seriously interested.
>
> - Mike
>
>
>
>
> --- On *Sat, 1/1/11, tsstproa /<bitme1234@...>/* wrote:
>
> From: tsstproa <bitme1234@...>
> Subject: [harryproa] Re: Hull slenderness ratios ww hull lengths
> To: harryproa@yahoogroups.com.au
> Date: Saturday, 1 January, 2011, 5:21
>
> I know it probably sounded like a really simply question that one
> obviously could have answered him/her self. But coming from a Pacific
> proa stand point, regardless of windward hull length. Your adding to the
> over all weight of proa by having a windward hull large enough to
> support weight of stuffs and crew. Would that be a logical conclusion?
>
> Never thought of Robs windward hull as having a wide waterline beam,
> just large structure with large amount of volume.
>
> I tend to believe making windward hull as high as possible in length to
> beam ratio for the given length and weight to be carried for a given
> draft. Especially for the smaller craft. To compensate for shorter length.
>
> Haven't run the displacement for what draft numbers, but running a WW
> hull 4.26m/ 14' length with a waterline beam width of 25.4cm /10'' gets
> you double your 8/1 for a 16.8/1 length to beam ratio. Pushing it to
> 16'L x 12''w gets you greater weight carrying ability on a little wide
> waterline beam with a 2'' increase from 10'' to 12'' with a 16/1 ratio
> or keep the 10''wlb for 19/2 ratio, just a thought. Whats your load out
> on extended cruising and the weight when just out for a day sail on
> windward hull? +/-
>
> Todd
>