Subject: Re: [harryproa] Rudder geometry?
From: "Rick Willoughby rickwill@bigpond.net.au [harryproa]" <harryproa@yahoogroups.com.au>
Date: 6/6/2018, 7:30 PM
To: "harryproa@yahoogroups.com.au" <harryproa@yahoogroups.com.au>
Reply-to:
harryproa@yahoogroups.com.au

 

The bigger ones I have seen have two wheels that work independently.  Both wheels work intuitively whether you set course with the leading rudder or the trailing rudder.   


My observation on the 18m proa in low wind, the trailing rudder is set to counter the weather helm and course kept with the leading rudder. Above light wind when boat speed is above 6 knots, leave the leading rudder in line and hold course with the aft rudder.  It is possible to eek out slightly better speed to windward working both rudders particularly if there is a swell.

I have found it is nice to be able to reach both wheels when facing forward rather than being beside the wheels. 

In tight spots both rudders get used and turning is responsive as long as boat speed is above 3kts.  


On 7 Jun 2018, at 9:10 am, markm@snowgum.com [harryproa] <harryproa@yahoogroups.com.au> wrote:

I'm curious about how the rudder geometry gets set up on a Harry Proa with a single wheel or whipstaff and symmetric rudders. My assumption is that they are setup with the equivalent of a crossed arm joining the two rudders so that if I am turning right, the bow rudder steers the bow to the right and the stern rudder steers the stern to the left, causing the boat to rotate to the right. Anything else I can think of ends up not working when you reverse direction. Assuming I have this right, it leads to a couple of questions/comments:

 - does this make the steering unduly sensitive when going straight, or is it just a matter of getting used to fine movements

 - is there some way to have the geometry between the rudders adjustable? e.g. fixing the forward rudder's angle of attack going upwind and steering with just the aft rudder, or making them work in parallel when docking? or is it not worth it in practice?


Just doing a thoug ht experiment on what it would be like sailing a harry proa on a day to day basis cruising. As an FYI I come from the perspective of having cruised for 4 yrs on a Catana 48 where I knew how to make the boat do exactly as I wanted in tight quarters with the combination of rudders and twin engines. It seems like the Harry Proa might be just as manoeuvrable with an engine on a dinghy sled, a small electric trolling motor and the two rudders, but I'm having trouble picturing it. 



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Posted by: Rick Willoughby <rickwill@bigpond.net.au>
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