daggerboard rudder

It is described as a "rudder thats slides up and down in a rotating cylinder" No details are given. This is from a set of download study plans that used to be available on the Crowther website. Conventional spade rudders were an option.

 

Thanks Jamez, it sounds like a good idea for a proa too. No kick up, but maybe lighter replaceable blades.

 

I can't find Uwe's email address. I seem to recall he used high density plastic bearing on fiberglass. I also recall there were difficulties with the rudders on the "gunboat 33" (?), predecessor of the (completely redesigned) Moxie.

 

One thing that disappoints me with my cat is the fixed rudders effectively killing off the possibility of beaching it on low tides.

Im not planning on doing anything radical like these tube rubbers.... but they do look like a good option if I ever got bored. Juts goes to show there is a solution for everything!

 

Hi James, Sorry for the thread drift....you wouldnt happen to have a copy of the study plans for the Crowther Shockwave 37 would you?

 

I could,nt find anything on the cylinder design when I was looking for it, what I saw was a rotating daggerboard, but could,nt rember if it was in some of Ed,s designs or someone elses. For me I think it will be easyer to go with the F boat rudder as I can buy a blank. Pogos rudder looks good but I would have to get some design work done in order to build. The cylinder design would fit in the outboard well and make good use of the space, but again design work would have to be done . rick

 

No I'm afraid not. I found an old version of the website with the wayback engine that mentions the design but it wasn't hyperlinked to anything (not that many of the links seem to work).

http://web.archive.org/web/20000116183258/www.crowther.com.au/sailing.htm

http://web.archive.org/web/*/http://www.crowther.com.au

There was an article in May/June 1984 Multihulls Magazine. If you contact them they may be able to scan it for you. Good luck - its a bloody shame all this old Crowther material is no longer easily available.

Cav, I know i read something with more detail of that barrel rudder somewhere, but I can't @#!^ remember where.......... maybe an old issue of Multuhull world ??

 

Hi james, Thanks for the snippets, cheers
Brett

 

Hi Brett, sounds like you've picked up a nice boat. I'm looking forward to seeing the results of your rebuild/revamp.

In case anyone else is interested the Crowther study prints I have (downloaded in about 2002 IIRC) are for:

Design 228 - 29 foot cruising open wingdeck cat

Design 274 - SP35/40 bridgedeck cat

Design 325/235A 33 and 40 foot racing pod-cat

 

I'll look for it. Its one of those simple ideas with complicated problems to solve. More bearing area-fouling build up in the barrel- corrosion etc.... but intriguing.

 

I remembered that Eric Sponberg had done a design for a "rudder in a drum" and I finally found the thread: http://www.boatdesign.net/forums/boat-design/rudder-drum-25041.html
Hope it helps....

 

Thanks Doug, it looks like a lot of development has already gone into this wheel. This info should help anybody wanting to adapt the technology.rberrey, Ed Horstman did have rotating daggerboards for adjustable lift way back when.

 

Here is a kickup rudder that has a fixed plate above it that becomes part of the hull when down. Eliminates the surface piercing aspect of a "normal" kick up rudder allowing the same "endplate effect" of a rudder that is fixed under a hull:

(click on image)

 

Wing topped rudders also tend to flatten out the transom wave, decreasing resistance and if shaped properly can offer some lift as the boat tries to squat.

 

I believe Shuttleworth popularized this design among multihullers.