So, in short, your finding is to sail the HP in Atlantic fashion in light winds going close hauled and in the classic Pacific fashion in all other conditions; weighing down the ww hull is good in both fashions. In light winds this is not a safety concern. Correct?
--- In harryproa@yahoogroups.com.au, Rick Willoughby <rickwill@...> wrote:
>
> It is an observation that with the offset sail drive there is better
> control in light winds if the boat is sailed opposite to intended
> way. Conventional sail boats give two options - port or starboard
> tack. And both are reasonably balanced in light air. With a
> harryproa there are four options - two with lee helm and two with
> weather helm.
>
> This boat with existing rudders, 1m deep and 0.4m chord, cannot be
> sailed slower to weather than 2.5kts with wind over the ww hull. It
> just rounds up and is in irons until the sail is backed and the boat
> reversed out of irons. Going to weather in windspeed below 5kts can
> only be done reliably by sailing with wind coming over the lw hull.
>
> It is simply a practical way to sail the boat in light wind. We were
> holding between 4 to 5kts making less than 40 degrees to true wind
> sailing the wrong way around. (I have the GPS track and wind
> direction from doppler radar but there is a time shift and it is too
> good to be true - that said we were sailing faster and possibly
> higher than a modern cruising cat and 30+ft keel boat.) In the same
> conditions we made 3 attempts to sail to windward with the lw hull on
> the lee side. Speed was between 2 to 3kts but inevitably there would
> be a wind shift or loss of concentration and the boat would round
> up. We gave up beating and just sailed off the wind. By that stage
> the wind had picked up a bit to average about 7kts and we were making
> 6 to 7kts reaching. If the boat could be sailed in both directions
> we would have been better off sailing with the ww hull on the lee
> side on both tacks. However the current rudder set up with chain
> makes bi-directional sailing dicey.
>
> If the mast was stepped more centrally (on the bridge deck rather
> than lw hull) then the weather helm could be eliminated but the wide
> open space of the bridge deck would be reduced.
>
> Arguably the strong weather helm when sailing normal way around is a
> safety feature. Also there is a strong tendency for the lw to stay
> downwind with the mast stepped in the lw hull..
>
> With a beach cat it is possible to unload the windward hull when
> beating in light air by moving weight onto the lee hull. Loading one
> hull reduces drag. This is not possible with typical cruising cat
> unless you have large crew or movable ballast. With a harryproa it
> makes sense in light air to unload the lighter hull and maximise the
> load on the heavier hull, which is usually the ww hull.
>
> The 18m proa was not intended to sail with the ww hull on the lee
> side but it works well for light conditions. The jib only has tell-
> tales on one side and this makes trimming a bit more difficult when
> sailing the wrong way but is something that could be fixed easily.
>
> Having two different hulls and being able to sail both ways gives
> more boat tuning options. We have now found the fastest way of going
> to windward in light air with a harryproa. Something others could
> test as well.
>
> Rick
> On 31/12/2011, at 9:42 PM, LucD wrote:
>
> > Is that an argument against an asymmetric lee hull too? Luc
> >
> > --- In harryproa@yahoogroups.com.au, Rick Willoughby <rickwill@>
> > wrote:
> > >
> > ...
> > > One other learning of note. From a performance perspective there is
> > > no point in having a centreboard or keel that has a lower aspect
> > > ratio than the rudders providing the rudders can be operated
> > > independently. One consideration for the job list was fitting a
> > > long keel and reducing the depth of the rudders - essentially aimed
> > > at reducing draft. My analysis showed this would seriously impair
> > > windward performance. Roughly 10 degree loss in pointing ability for
> > > the same speed.
> > >
> > > All sailing yesterday was without a centreboard because the brace
> > has
> > > fatigued and no longer restrains the board laterally. Sailing the
> > > right way around was about the same without the board but sailing
> > the
> > > wrong way around was faster without the board because steering to
> > > counter the lee helm gets the leading rudder working to windward.
> > > Once the rudders can be worked independently the leading rudder can
> > > be set to counter leeway, which will do it more efficiently than
> > > relying on the hulls.
> > >
> > > Rick
> > >
> >
> >
>
> Rick Willoughby
> rickwill@...
>