Subject: Fw: [harryproa] Re: sailing Elementarry
From: "proaconstrictor" <>
Date: 2/10/2006, 3:55 PM

> >
> > Right, stabilizing with mast bouyancy is not what one wants in
> > kind of situation that causes a capsize in the first place. 
> > Self-righting is the proven concept
>   Could you explain this in more detail?  I think that self-
righting is
> a wonderful thing, but don't yet see how a leeward-pod proa would
> itself in a knockdown or wave-induced capsize.

I should point out that when I talk about pods I'm talking about
cruising sized boats not Elementary righting.  So far the
Elementaries I have seen pictures of are just fancy pacific proa
beach cats, not HPs or analogs for other crusing designs.  So if I've
missed the whole point by a massive scaling factor, then I appologize.

The way self-righting works, is that the CG is well below deck, when
the boat nocks down podside, the pod is so deep that it is in essence
another hull.  In the KD position the boat is floating on this second
hull with the GG well to windward.  the assumption is the boat has
been KD by a gust as with Cheers during it's test cruising.  Cheers
did not right because it hadn't a pod at the time.  The sails loose
the wind as the boat is knocked down, and the gust subsides.  The CG
is well to the side of the CB so the boat climbs back up to the point
where the float weight returns the boat to the upright condition.

>   I can see how the leeward-pod proa will work well for a wind-
> capsize, especially if the knockdown isn't complete.  Forgetting
> rig, that pod will keep the boat from going over in many or most
> so there's no need to worry about mast buoyancy.
>   But what about a more extreme condition, such as a massive gust,
> large steep wave, or a combination of the two?  If something were
> push a leeward-pod proa past 90 degrees, how could it be righted
> I would think that anything that extends past the hull would make
> more difficult to flip the boat back upright..

There is certainly some condition where the boat wrecks.  exactly
what that conditionis is depends on service it was designed for.  The
Newick boats were designed to take advantage of light weight and low
resistance to be sailable out from underneath the rest of the fleet
in ideal conditions.  Newcik sends out an AP study plan with his
standard packet, so he still thinks they are relavant. I have
wondered how they remain relavant, since materials have changed to
the point where a cat or tri could be built too light for heavy
weather with a full racing footprint.

Pacific proas are harder to figure out.  Rob had an actual reason for
building the first ones during the "my wife doesn't like to sail"
phase.  Again a low resistance idea, big fooprint, small rig.  Russ
is doing whatever he does with a boat that is not the ultimate sea
survivor, but it can recover from a nockdowm. It really works a lot
more like a monohull, right down to sailing with a fair amount of
heel.  It is hard to argue it is the most practical arrangement for a
given bag of materials, but then as his father points out, all boat
technical talk is just a rationalization for ones preferances.  It's
hard to argue Russ' boat would be more practical without the pod.

>   It seems to me that a) the harryproa will normally have a greater
> righting moment when sailing, 

Obviously this depends on establishing some criterion like money or
weight.  HP only works with a large carbon budget, and with the
assumption of some catamaran propeties.  I;m all good with that, but
I don't think we have seen many boats try to approach this design
prameter.  And the other thing is that so far we all see to be going
along witht he idea that HPs never get caught aback.  I;m certainly
comfortable with your claim though. 

b) while the leeward-pod proa will be
> more resistant to capsize if you push the boat past 30 degrees, but

It basically can't capsize, unless it gets really mangled int he kind
of conditions that would roll a monohull, but knocking it down well
past 30 deg is not out of the question, and might be called easy.

> the harryproa will have a much greater chance of getting back on
> feet if pushed to 90 degrees.

Totaly disagree.  The excetion being that maybe the LPP only gets to
75-80 degrees in the first place.

A cruising HP at 90 degree is capsized, isn't it.  And elementary is
just a toy but a Vision, or Harry at 90 is a salvage job.

>   It's a series of tradeoffs  I like the harryproa approach, but
> clearly biased.  However, if I can learn how a leeward-pod proa
> self-right, that could certainly change things.

The thing is that all these boats seem permanently apples and
oranges.  There are a lot more problems with a Russ proa than safety,
like the minimal and chopped up accomodations.  The Harry doesn't
seem to be designed for the same purpose, it's variously described as
a family camper or a race boat, but the claims are practical. 
Anyway, only Rob has plans.

>        - Mike

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