Subject: [harryproa] Re: mast bouyancy
From: "Robert" <>
Date: 2/14/2006, 1:43 AM

-If I had the drogue set up I would be wanting to avoid being side
on, lying ahull. I feel surface area is too great to withstand such a
hit of white water. Neither would I want a lee brake as it would
contribute to flipping torque. For having a dinner or snooze break in
moderate weather, lying ahull would be comfortable and stable.
I have tried to come up with a lee bouyancy that did not reduce 90
degree stability and it requires an excessively tall lw hull to be
effective. Won't say it can't be done , but it is beyond me.

-- In, Mike Crawford <jmichael@g...>
> <<It would be easier to lift the 350kg weight of the hull... This
> only 700-900kg off a 3m gantry.>>
>   Good point.  Not unimagineable once the weather has calmed down
> swells.  If those masts are sealed, you can add another 150-400kg
> flotation, depending upon the rig, making it a bit easier for that
> gantry to work.
> <<the recommendation is that the drogue is to go over the stern>>
>   And which end of a harryproa would that be?    ;-)
>   I know, you answered the question.  Fortunately the proas work in
> directions, so as long as the boat is stabilized windward, as as
> you've suggested, there's no need to worry about it being
unseaworthy in
> one direction versus another.
>   I must correct something I wrote the other day.  The goal was to
> some sort of anchor to windward, be it a para anchor or jordan-type
> drogues, along with a minimal break, such as a good length of bare
> chain, off the leeward end to help resist surfing after the wave
> passes.  I shouldn't have used the term drogue for the leeward
> Towing drogues while being dragged behind a sea anchor could get
> weird.
> ---
>   Another option would be to keep the windward hull to windward,
> ahull to the weather, and fastening the drogue bridle off of each
> That would provide a similar effect to tying the drogues to the the
> stern of a monohull, thereby using its flotation to keep it with
> wave surface instead of trying to crash through the wave the way
the bow
> would.
>   Since the proa is so stable in that direction, and the boat is so
> light, you wouldn't need extreme forces to keep the boat from going
> over.  Because of the 6m beam, even bare poles would enable the
boat to
> weathercock into the right position without additional help.
>   Lying ahull would also be useful with preventing the surfing
> that a fast boat can have once it crests the wave.  As long as
> aren't any keels on either hull, there won't be anything to catch
> the water and spill the boat as it slides sideways.  That would
> eliminate the need for a leeward break, which some argue is not a
good idea.
>        - Mike
> Robert wrote:
> > A fully flooded Harry lw hull will have in the order of 300-450kg
> > bouyancy and you would need to move ~9 tonnes of water to fill the
> > hull. It would be easier to lift the 350kg weight of the hull (add
> > another 100kg or so for masts and rudders), especially encouraged
> > mast bouyancy. This is only 700-900kg off a 3m gantry. You only
> > to work a distance of 4m or so. This is no more than I have done
> > hauling vehicles up a slippery slope. With the right winch,
> > exhausting but doable- or maybe you could fly a kite ;-)
> >
> > I've been reading the Jordan series drogue website and the
> > recommendation is that the drogue is to go over the stern as it
> > the windage and the under water resistance such that the boat
> > tack up on the rode to end up side on. On a Harry, slight rudder
> > on the end where the waves are coming from and a tiny bit of rag
> > the opposite end mast would similarly stabilise the boat I think
> > reports on the website well worth a read
> >
> > regards,
> > Robert
> >

Yahoo! Groups Links