Subject: Re: [harryproa] Re: rudder depth
From: "Rob Denney" <proa@iinet.net.au>
Date: 3/3/2006, 3:33 AM
To:
Reply-to:
harryproa@yahoogroups.com.au

Like everything, the strake is worth a try.
 
I have not done so as I have had no problems with either tracking (apart from the single rudder being too far forward, which is only a low speed problem) or leeway prevention.  Give it a shot and see what happens.  I would a) do it after sailing so you can compare b) not spend a lot of time making it perfect, so you won't mind so much pulling it off.
 
regards,
 
rob
----- Original Message -----
From: Robert
To: harryproa@yahoogroups.com.au
Sent: Thursday, March 02, 2006 9:29 PM
Subject: [harryproa] Re: rudder depth

-Makes a lot of sense. The whole box breaking away reduces the chance
of the rudders jamming under the crossbeams during a collision,
especially if you could have a top fuse that gave way before a bottom
fuse.

I've been thinking of whether it might be worth increasing the
tracking and leeway prevention by a rubbing strake (about 10-15mm) on
the bottom with a sharp edge to lw and faired to ww (a small strip of
aluminium channel on a jarcat has shown to be as effective as
minikeels) and/or having a slight V to the bows. The strake would not
prevent the ends moving to ww under rudder and the slight V may also
help in short sharp chop at speed, and if widened above slightly,
could help in the release of the stern. I am assuming the use of two
rudders would overcome the extra resistance to turning but realise it
would probably slow shunting
regards,
robert

-- In harryproa@yahoogroups.com.au, "Mark Stephens" <stephens@o...>
wrote:
>
> I'm intending to cut 500mm from the bottom of the Visionarry
rudders. I'm redesigning and rebuilding the boxes so I will angle the
blade more forward to retain the balance. They will basically work
the same as before except the whole rudder box will break away when
the shear pins break, leaving behind the pivot shaft and quadrant.
This way I can use most of the same components as before avoiding a
total rebuild. This is still the best option until the drum rudders
prove themselves.
>
> Mark
>
>
> Mark Stephens
> www.harryproa.com
> 0431 486814
>   ----- Original Message -----
>   From: Robert
>   To: harryproa@yahoogroups.com.au
>   Sent: Wednesday, March 01, 2006 8:33 PM
>   Subject: [harryproa] rudder depth
>
>
>   with the tracking ability shown by success of the single rudder
>   elementarry, is it possible that the rudders on the Visionarry
don't
>   need to be as deep. A 10% decrease in depth would be  a 10%
decrease in
>   wetted area and about an 18% decrease in the load on the rudder
>   supports.
>   regards,
>   Robert
>
>
>
>
>
>   
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