Re: [Paddlewise] Rudders

From: Alex Ferguson <a.ferguson_at_chem.canterbury.ac.nz>
Date: Fri, 05 Oct 2001 13:24:02 +1200
>[Mary]
>I am not sure if you have looked at this system, but the blade is very
>different from usual rudder systems because it is much smaller.

That means that is too short. The blade I have on a rudder with the same 
approach (vertical stowed blade) stood miles up in the air. The pivot could 
not have been any lower or it would have been under water, the support 
block usually touched the water, and the blade could not be any shorter to 
be effective. If the pivot is any lower there won't be enough mechanical 
strength/support for the blade which will bend or split the mounting block.

>  The pivot
>point for the rudder is lower than a conventional system so consequently it
>does not have to drop down as far.

If you put one of those on a Sea Yak the blade wouldn't even get wet - too 
short to reach the water.

>   When the blade is retracted it comes up
>from the lower pivot point and it is shorter so it doesn't stick up very far
>at all.  I didn't measure it but it didn't extend much farther from the deck
>than a conventional rudder.

That means it would only be long enough on a high decked kayak if the whole 
unit was mounted at water level otherwise the blade is too short for 
anything other than flat water paddling.

>   It has less surface area so there is less wind
>drag when it is up.

Even less efficient no matter how good the foil shape is.

>The other thing I liked about the system was that the blade has a spring
>that causes the blade to retract if you forget to take up your rudder when
>you get into shallow water or get into heavy bull kelp,

You mean drops the blade into the water, a string pulls it up(?). We do 
mean retract when we pull it out of the water? A properly designed system 
allows "kickup" at some predetermined load. The spring is a high-tech 
equivalent of a bit of bungy.

Alex
.
.

***************************************************************************
PaddleWise Paddling Mailing List - Any opinions or suggestions expressed
here are solely those of the writer(s). You must assume the entire
responsibility for reliance upon them. All postings copyright the author.
Submissions:     PaddleWise_at_PaddleWise.net
Subscriptions:   PaddleWise-request_at_PaddleWise.net
Website:         http://www.paddlewise.net/
***************************************************************************
Received on Thu Oct 04 2001 - 18:24:10 PDT

This archive was generated by hypermail 2.4.0 : Thu Aug 21 2025 - 16:30:45 PDT