|Subject: Re: [harryproa] Harryproa design page|
|From: "Rob Denney" <email@example.com>|
|Date: 4/13/2008, 12:57 AM|
I tried non rotating foils a while ago, but as JT said, they do not
work as well as rotating ones. There are also balance issues at high
speed. The balance is not a simple function of where the shaft is.
We usually put the shaft at 20% of the chord which gives enough
balance without the likelihood of the centre of force on the rudder
getting ahead of the centre of rotation and causing the rudder to
rotate. This would be disastrous.
With the two rudders it is pretty easy to get the boat to steer itself
for a minute or two. I have not tried for longer. When i was playing
with the Outleader kite on Elementarry I regularly locked the helm
while I sorted out tangled lines. Zero rocker makes for excellent
I will be testing this further on the solo 15m/50' boat which will not
be having an electric autopilot.. If it won't steer satisfactorily
for 20-30 minutes at a time, I will try a wind vane. If that doesn't
work, I will just dump the sheets while i sleep.
On Sun, Apr 13, 2008 at 5:03 AM, George Kuck <chesapeake410@
> If rudder is symmetric there would never be any reason to rotate more than
> 180 (and likely less than + or - 45), You would simply switch leading edge
> on rudders when you shunt.. Is this what you envision or will you expect to
> rotate rudder 180 when you shunt ? If you do plan on rotating 180 then
> would it make sence to have a 40/60 or other balance ratio on rudder so it
> will have a tendency to rotate on its own when you shunt. This would also
> prevent ruder being stalled at 90 degrees and possibly risk braking sheer
> plate and would add some feel to rudder .
> One other question I have had that may be related to rudder design is the
> ability of the Harryproa to self steer by setting sail and locking rudder.
> It may require less than optimal settings for top speed but is it possible
> to let boat steer itself and on what points of sailing would this work best.
> This would be a good trait of the boat if it could be done without the use
> of autopilots or wind vane, even if only as a backup for other system.
> Happy sailing,
> George Kuck
> Chestertown, MD
> Rob Denney <harryproa@gmail.
> On Sat, Apr 12, 2008 at 10:31 PM, George Kuck <chesapeake410@
> > Hello Rob,
> > With wheel steering as on a 40' Harryproa will it rotate 360 and then have
> > to go back 370 to go an additional 10 degrees or will it be continuously
> > rotatable (to 370 or more). ? Will it be balanced so that there is no load
> > (50/50)or (40/60), or other ? Can rudders be rotated 90 degrees to use as
> > brake when at speed ?
> > Happy sailing,
> > George Kuck
> > Chestertown, MD
> Continuously rotating. Pretty much balanced although there are
> variations in the balance depending on speed, course, foil shape,
> fairness and smoothness. You can use it as a break, at least until
> the sheer pin breaks.
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