New Posts New Posts RSS Feed: Rudder rake effects?
  FAQ FAQ  Forum Search   Register Register  Login Login

Rudder rake effects?
 Post Reply Post Reply Page  12>
Author
  Share Topic Share Topic  Topic Search Topic Search  Topic Options Topic Options
Oatsandbeans View Drop Down
Far too distracted from work
Far too distracted from work


Joined: 19 Sep 05
Location: United Kingdom
Online Status: Offline
Posts: 382 		Post Options Post Options   Quote Oatsandbeans Quote  Post ReplyReply Direct Link To This Post Topic: Rudder rake effects?
    Posted: 27 Dec 21 at 9:49am
I have never understood why racing dinghies are so sensitive to rudder rake. In most boats I have sailed ( forget the laser for a minute) if the rudder is not fully vertical the boat feels like a dog. Anyone got any explanation?
Back to Top
iGRF View Drop Down
Really should get out more
Really should get out more
Avatar

Joined: 07 Mar 11
Location: Hythe
Online Status: Offline
Posts: 6499 		Post Options Post Options   Quote iGRF Quote  Post ReplyReply Direct Link To This Post Posted: 27 Dec 21 at 12:05pm
I always assumed it was caused by the extra pressure from the water flow leveraged more by the swept back angle, I hate when it happens, which it seems to a lot, with slippy cleats on two of my rudder setups and running aground down the lake knocking the rudder back and jamming the rope further into the cleat making rectifying it a ballache.
Snow Equipment Deals    New Core Kite website
Back to Top
423zero View Drop Down
Really should get out more
Really should get out more


Joined: 08 Jan 15
Location: United Kingdom
Online Status: Offline
Posts: 3420 		Post Options Post Options   Quote 423zero Quote  Post ReplyReply Direct Link To This Post Posted: 27 Dec 21 at 12:12pm
Blade is shaped for maximum efficiency in the vertical position, some are just flat though. Could also be increased cavitation.
Robert
Back to Top
Oatsandbeans View Drop Down
Far too distracted from work
Far too distracted from work


Joined: 19 Sep 05
Location: United Kingdom
Online Status: Offline
Posts: 382 		Post Options Post Options   Quote Oatsandbeans Quote  Post ReplyReply Direct Link To This Post Posted: 27 Dec 21 at 12:13pm
Yes that’s what I thought, but the centre of lift of the rudder is back from the pivot anyway so having the rudder not right down would only move it back a bit more but that bit seems to make a big difference to how the boat feels.( I struggled with the RS system of a rope in a cleat , always seemed to move.)
Back to Top
PeterG View Drop Down
Really should get out more
Really should get out more


Joined: 12 Jan 08
Location: United Kingdom
Online Status: Offline
Posts: 823 		Post Options Post Options   Quote PeterG Quote  Post ReplyReply Direct Link To This Post Posted: 27 Dec 21 at 12:14pm
Generaly (Lasers excluded!) they are designed to be nearly balanced, around the gudgeon/pintle axis when right down. If raked back they are unbalanced and the tiller load increases very quickly.
Peter
Ex Cont 707
Ex Laser 189635
DY 59
Back to Top
Noah View Drop Down
Really should get out more
Really should get out more


Joined: 29 Dec 04
Location: United Kingdom
Online Status: Offline
Posts: 611 		Post Options Post Options   Quote Noah Quote  Post ReplyReply Direct Link To This Post Posted: 27 Dec 21 at 2:02pm
On any boat with pretentious to any sort of performance, I’ve found that 2:1 down haul purchase is needed, and a decent (i.e. not worn out) break-out cleat that is properly adjusted.
Nick
D-Zero 316

Back to Top
Sam.Spoons View Drop Down
Really should get out more
Really should get out more


Joined: 07 Mar 12
Location: Manchester UK
Online Status: Offline
Posts: 3401 		Post Options Post Options   Quote Sam.Spoons Quote  Post ReplyReply Direct Link To This Post Posted: 27 Dec 21 at 3:02pm
Whenever a boat heels to leeward weather helm is generated, we pull the tiller to compensate. As Peter G says loads increase dramatically with a raked rudder as it has it's CoE much further behind the pivot than a vertical rudder.
Spice 346 "Flat Broke"
Blaze 671 "supersonic soap dish"
Back to Top
ColPrice2002 View Drop Down
Far too distracted from work
Far too distracted from work


Joined: 25 Nov 08
Location: United Kingdom
Online Status: Offline
Posts: 222 		Post Options Post Options   Quote ColPrice2002 Quote  Post ReplyReply Direct Link To This Post Posted: 27 Dec 21 at 9:19pm
Sailing with a raked rudder increases the force needed to steer. Simple leverage...

If the boat is absolutely flat, then there should be no force on the rudder...
Any heel and you'll feel it on the tiller.
Practice by rudderless sailing!
Back to Top
Riv View Drop Down
Far too distracted from work
Far too distracted from work


Joined: 23 Nov 13
Location: South Devon
Online Status: Offline
Posts: 353 		Post Options Post Options   Quote Riv Quote  Post ReplyReply Direct Link To This Post Posted: 27 Dec 21 at 10:44pm
I remember the first rudder I ever built, it was for an IC, had too much area forward of the shaft, went out turned around, just! Got back in and got the saw out.
Mistral Div II prototype board, Original Windsurfer, Hornet built'74.
Back to Top
JimC View Drop Down
Really should get out more
Really should get out more
Avatar

Joined: 17 May 04
Location: United Kingdom
Online Status: Offline
Posts: 6662 		Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 28 Dec 21 at 10:01pm
Originally posted by ColPrice2002

If the boat is absolutely flat, then there should be no force on the rudder...

Most modern high performance boats are tuned so that there is side load on the rudder. You are dragging the foil through the water anyway so it may as well contribute.
Back to Top
 Post Reply Post Reply Page  12>

Forum Jump Forum Permissions View Drop Down

Bulletin Board Software by Web Wiz Forums® version 9.665y
Copyright ©2001-2010 Web Wiz
Change your personal settings, or read our privacy policy