Subject: Re: [harryproa] Re: Current rudder design?
From: "Peter Southwood" <>
Date: 5/27/2008, 7:57 AM

Try Vesconite. Makes very good dry and water lubricated bearings.
Other similar materials may also be available Google it.
----- Original Message -----
From: Robert
Sent: Tuesday, May 27, 2008 6:40 AM
Subject: [harryproa] Re: Current rudder design?

There are a lot of lower friction materials than PVC! If they work
under those conditions, I can't see any problem once you get decent
bearing material--- In, "Rob Denney"
<harryproa@...> wrote:
> G'day,
> See Rough beam rudders & fea of rudder supports in the files section.
> The first one is an fea model for Blind Date's new rudders. Shows
> what happens with 7 tonnes of load. This has been built, should be
> sailing pretty soon. The others are pictures of the set up on my
> Elementarry (7.5m/25' test bed. These worked really well with both
> rudders, or just the aft one, although there were some bearing binding
> issues at speed. A function of pvc drain pipes for bearings, I think.
> Blind Date is having roller bearings to get round this. I am
> building much bigger diameter (still pvc drainpipe) to try and get a
> handle on the forces involved. Not sure why the pictures are so small.
> Does anyone know how to make them bigger?
> The rudders are roughly 1% of the sail area, with aspect ratio between
> 3:1 and 4:1, depending on the boat use. They lift to the depth of the
> hull and can still be steered. They kick up in either direction in a
> grounding or impact. Blind Date is using a rack and pinion to turn
> them, JT a spur gear, Solitarry a tiller and I am working on a
> quadrant. 360 degrees is great if you accidentally tack or luff too
> high. Simply reverse the rudders and steer in the other direction.
> Same applies for 270 degrees of course, but you have to be careful
> which way you turn the wheel, which could be an issue on the cgharter
> boat. 270 also needs two wheels as shunting and normal steering
> require them to go in opposite directions. With 360, one wheel will
> suffice.
> regards,
> Rob
> On Mon, May 26, 2008 at 9:30 AM, gardnerpomper <gardner@...> wrote:
> > Hi,
> >
> > Is there any information (sketch or drawing, preferably) of the
> > current rudder design? This is one of my areas of concern, and I would
> > like to see what the current thinking is. Specific questions are:
> >
> > what are the dimensions of the rudders?
> >
> > are they designed to lift in the rudder assembly for shoal draft
> > sailing, or do they tilt?
> >
> > Do they need 360 degrees maneuverability, or just +/- 45 degrees from
> > the direction of motion? (i.e 335-45 degrees, and 135-225 degrees,
> > relative to the hulls)
> >
> > I am specifically speaking of the charter proa, but I am curious if
> > the basic rudder design applies to pretty much any size harryproa.
> >
> > Thanks,
> > - Gardner
> >
> >

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