Subject: Re: [harryproa] Rudder Harryproa
From: "Rob Denney" <>
Date: 4/4/2008, 8:30 AM


> The bigger rudders are designed to break a shear pin and the rudder kick up. The supports are plenty strong enough when kicked up, but the rudder will only rotate, without steering the boat. If you plan on spending any time in shallow conditions, the rudders can be made to lift so the top of the blade is under the beam. Another alternative is a telescoping rudder which is very simple to do. Both these bring the rudder up to the same depth as the ww hull, so you would get your 3' no problem.

Being able to lift the front rudder is a speed enhancer. It is a lot
easier with the beam mounted rudders (remove a shear pin and the
rudder floats up, then lift it clear of the water.

Making a rudder where the blade sings up but the axis stays vertical
can be done, bit will be pretty draggy. Not sure it is worth the
work. but if you want to have a go, I will draw it for you.



> What happens when going up to harry size?
> - the rudders were designed to BREAK OFF at a pre-built weak point? I read
> this in the site I think.
> -What I would like is to be able to sail Harry similarily to SideCar and not
> care if it goes from 6 feet deep to say 3 feet.
> It is harder to steer when the blade swings back, but I still get over the
> and bank allright, then pull it down again.
> If Harry rudders just lift straight up then there isn't too much diffrence
> in sailing with 3 feet rudder than 6 feet in that the bottom might stick up
> and still touch, so by breaking something. I can't imagine taking a dagger
> style Harry into any where shallow, thereby losing all the shoal draftness
> exceopt for coming in with just motors. Is this an expected sailing practice
> of most people - to only sail in deeper water, and only motor when in water
> less than I don't knoew exactly, when you aren't sure its deep enough for
> the 6 foot or whatever.
> I'm distinguishing between marina to marina, deep anchorage/long tender
> journey cruising, and coming in to next to the beach ( where the shelter is
> the best). Plus sailing across short cuts or bays/ coastal sandy places
> which one might like to go to or through.
> Just wondering if I can get something on a big scale to swing up, rather
> than breaking a pin every time grounding along the bottom. Of course my ones
> don't swing both ways so what does it need?
> Thanks for your time and effort
> Doug
> Rob Denney <> wrote:
> G'day,
> Blind Date is getting an electric motor this winter. The 66'ter in Portugal
> and the 60' charter boat are both planning on having them as well.
> Putting them on the rudders solves the two way problem and gives amazing
> maneuverability. Would only need one if it was powerful enough. No real
> drawings yet, but the principle is a sleeve that slides up and down on the
> rudder blade with the motor attached to it. Lift it clear of the water when
> not in use with a block and tackle, ease the rope to lower it. Much cheaper
> and more reliable than the African Cats system. Kicks up on impact and
> very accessible for clearing ropes and stuff off the prop. Also (smug
> grin) not usable by boats without beam mounted rudders.
> Another version is the e jet
> regards,
> Rob
> On Thu, Apr 3, 2008 at 10:26 PM, chesapeake410 <>
> wrote:
> >
> >
> >
> >
> >
> > Hello,
> > I am planing on building a 12 m Harryproa and am thinking of using
> > electric pods. Pods would be mounted on swing arms similar to what
> > has been used on African cats. Take a look at the June 14,2007 press
> > release on website. Also check out .
> > In the Re-E-Power Forum link in the photo section is a example of a
> > pod mounted to a long swing arm.
> >
> > Has anything been done with electric power on Harryproa's ? I think
> > there was a recent reference to electric motors on rudders, does
> > anyone have more information or pictures on this.
> >
> > I think a Harryproa would be unequally suited to a solar/battery
> > electric drive system since the sail is offset on lw hull. A solar
> > canopy over the seats a center area of boat would be less obstructed
> > by sail than a cattermaran.
> >
> > The proa does have the problem of how to deal with going in both
> > directions with the electric drive. You could point one in each
> > direction and only use one in open water and lower both for
> > maneuvering in harbor or for extra power when needed. You could use a
> > prop designed for both directions but I do not know it it would be as
> > efficient as one designed for one direction.
> >
> > I would like to hear any sugjestions and comments one this ?
> >
> > One other concern would be the added weight of a battery pack which
> > could be as much as 1000lbs or more. I am hoping that newer battery
> > types will bring down the weight in the next few years to less than
> > 600 lbs.
> > Valence Technology Lithium batteries would be great but the current
> > price is prohibitive. Firerfly batteries (a new lighter type of lead
> > acit battery) sound like a good bet but are not yet available. It
> > may be necessary to start with current lead acid and switch to
> > lighter batteries in the future. After Lithium batteries get
> > established in electric cars that will start coming out in the next
> > few years I expect availability and price to improve. I spoke with
> > Bob Lutz vic chairman of General motors at a special event a the New
> > York Auto show a week or two ago and he claims that they will have
> > the Chevy Volt in production by the end of 2010 ! It will run on
> > lithium batteries.
> >
> > Thanks for any imput on this topic,
> >
> > George Kuck
> > Chestertown, MD
> >
> >
> ________________________________
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> A Smarter Inbox.

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