Thanks, Robert. I was feeling wordy and inspired at the same time.
A business deal might let me build a boat sometime in the next two
years, so I was gripped with enthusiasm about how it all comes
together. First we build our house, though.
Right now I don't have time for a sailing anarchy discussion. My
wife is in the hospital (she'll get better, fortunately) and I have to
care for our infant daughter full-time as well as get paying work done.
Please feel free to post anything I say here in other groups. No
need to attribute it to anyone -- most has been said first by Rob at
one time or another I'm just fascinated by the design.
- Mike
Robert wrote:
Mike ,
this is a very nice summary.
Any chace of posting it on Sailing Anarchy as there is a bit of a discusion going on there at the moment.
On extra sail area, Rather than always having the extra height, if you are going to have the extra track, you could fit a 5-6m spar with about 1m of bury onto the track As it is only needed for light winds,
It doesn't have to be made too heavy. You could then fit a large lightweight main if you had a boom extension. 30% higher and 30 percent wider gives a 60% increase.
--- In harryproa@yahoogroups.com.au , Mike Crawford <jmichael@...> wrote:
>
>
> Proas are no more likely to capsize han other multis. It's a simple
> equation of heeling moment (sail area) versus righting moment (boat
> weight, moveable ballast, crew).
>
> As you point out, the pacific proa crowd feels their design is
> perfect. As Rob points out in his online articles, it's perfect with a
> crab's claw sail, on a beam reach, in trade winds, with highly-trained
> nimble crew who can dance windward and leeward to keep the log at the
> right level. Since the goal is to sail at the maximum heeling moment
> most of the time, this invites disaster if you don't have the perfect
> crew and conditions.
>
> It's the same reason why the Reynolds 33 is proclaimed a dangerous
> boat and forbidden from some race circuits. It's got a massive rig, and
> people like to use that rig to fly a hull as much as they can. I've
> been on one and while I was only able to fly a hull for a few seconds at
> a time due to light winds, I have to say it's great fun. But I don't do
> that with my own cat because I'm normally out alone. If you fly a hull
> long enough, you're going down. Maybe not for months or years, but it's
> only a matter of time. It doesn't make catamarans dangerous, and it
> doesn't even mean the r33 is dangerous. It means that capsizes happen
> when people sail multihulls right on the edge for long periods of time.
>
> You can argue that a Harry is less likely to capsize than an
> equivalent cat or or tri for the following reasons:
>
> - Longer waterline keeps the bows from digging in.
>
> - Sailing forces directly in line with the leeward hull, which is also
> the longest hull, help to keep the boat from tripping over an
> equivalently shorter catamaran hull, or worse, an even shorter trimaran
> hull.
>
> - A greater percentage of weight to windward will provide greater
> righting moment for the same sail area. This is a safety feature as
> long as you use it carefully though -- you could just keep pushing until
> you're flying a hull, and then you're on the edge again. Nonetheless,
> this righting moment may let you hit your max reasonable speed long
> before it's time to fly a hull anyway, in which case there's no need for
> white knuckles.
>
> - The flexible carbon mast will absorb gusts that would put a stayed
> boat right over. If you're near the edge with a stayed mast, there's no
> way to stop quick a gust (quick enough to where dumping a sheet or
> traveler won't help -- because you're on the edge), which might be 40%
> stronger than the average wind speed. But if the mast can flex, you
> gain a lot more reaction time, especially if you're got a rig that can
> dump force at a moment's notice (see next point).
>
> - A balanced easyrig will let you go to near zero heeling moment at
> any time. This is extremely important (whether on a proa or other
> multi) if you want to push the envelope safely. Dumping a mainsheet on
> a normal sloop rig sometimes adds to power and heeling moment, and
> sometimes can't be done. Dumping a large headsail can also be
> problematic. Trying to dump both at the same time, singlehanded, is
> highly unlikely. Going to zero on an easyrig Harry is as simple as
> releasing a single sheet.
>
> - A balanced rig will let you infinitely tune the heeling moment at
> any point of sail, even dead downwind. Anyone who has ever been caught
> in a multi running in winds close to the pitchpoling force will tell you
> how vital this is. It's quite scary to be out there knowing that you
> can't reduce sail area because the main in pinned to the shrouds, and
> you can't simply round up because that might cause you to dig in a bow
> and either capsize or pitchpole.
>
> - You can always shunt, at any time, even if you're 50' off a lee
> shore, and do so while feathering the sails on "just so", in order to
> avoid any sudden stresses. Trying to gybe, or come about through 200+
> degrees, in a catamaran or tri, while eyeing the granite of a lee shore,
> is not a good feeling. Being able to just switch direction is a superb
> safety feature.
>
> - You can always just reverse. There are times when the wind and wave
> period/height make a given angle of sail too dangerous to continue, but
> at the same time too dangerous to let a cat or trimaran turn around
> safely. Instead of trying to negotiation the mother of all turnabouts,
> you just head back in the other direction. That's as valuable in
> preventing capsize as the ability to shunt.
>
> - This is the one multi design that could elegantly self-right after a
> knockdown without any outside assistance. If your boat is light enough
> and the wing mast is tall enough (to provide enough flotation), this
> turns a nightmare into simply a bad day. Trying to do that on a 40'
> multi of any other design wold be highly unlikely. While I don't think
> anyone has tried this, or wants to try it, on the cruising Harry's, Rob
> has done it many times on his Elementarry , and the physics work the
> same with a heaver boat and taller masts.
>
> ---
>
> I'd say that as long as you're sailing wisely, and not trying fly a
> hull all the time, you won't find a safer design.
>
> I'd personally go with a taller and/or telescoping mast if you want
> more speed. That preserves all the benefits of the balanced rig listed
> above. Besides, does anyone other than a Decision 35 crew on Lake
> Genevia really need to push the SA/D past 50 or 60? If you're already
> there, I'm not sure it makes sense to ask for more sail area.
>
> But as Robert points out, this does mean you'll either have a taller
> mast or a telescoping mast. I'd probably go for taller, both for the
> sake of simplicity and also for preventing going past 90 degrees in the
> event of a knockdown. But since I'm primarily a daysailer, my opinion
> is skewed.
>
> - Mike
>
> / /
> Gardner Pomper wrote:
> >
> >
> > Hi,
> >
> > I have been listening to a podcast called "Furled Sails" which is
> > mostly about small sailing craft. One of the events they have covered
> > alot has been the Everglades Challenge, which is a 300 mile race from
> > Tampa, FL to Key Largo through the Everglades. It is mostly kayaks and
> > open monohulls, but they have had a few proas as well.
> >
> > The reason I am posting is that they have made a number (3 or 4)
> > comments about proas having not being able to sail downwind well. I
> > don't know if they mean speed or stability. Most of the criticism I
> > have heard about proas has been capsizing; not downwind performance.
> > Can anyone here tell me if there is an issue with proas sailing
> > downwind?
> >
> > I assume the proas they are referring to are traditional pacific
> > proas, so I figured I would just get denials from the regular proa
> > groups. I thought people here might have more objective and informed
> > opinions.
> >
> > If this is purely a sail size issue, I have a related question. Would
> > it be possible/reasonable to extend the forward boom on an easyrig and
> > mount a roller furled screacher there for light wind and downwind
> > performance? Maybe sheet it off to the end of the main boom?
> >
> > Thanks,
> > - Gardner
> >
> >
>
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