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Old 04-17-2015, 10:27 AM   #1
City: Whitehall Mi.
Join Date: Jan 2015
Posts: 13
Rudder modification

I recently read an article about a modification for trawler rudders. An academic group reshaped the flat plate rudder of a working trawler with a specific NACA profile. The end result was improved rudder response and increased rudder angle before stalling. Does anybody have any experience with this?

Dan Girvan
Gypsy Spirit
Albin 36

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Old 04-17-2015, 10:50 AM   #2
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Posts: 4,079
If you do a search you'll find a thread or two about this.

Jay Leonard

New Port Richey,Fl
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Old 04-17-2015, 12:47 PM   #3
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City: Concrete Washington State
Vessel Name: Willy
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If you have big rudders and go 7 knots you might try rigging your rudder to get more deflection. There were three holes on my rudder horn and I moved the hyd cyl rod attach point to the hole closest to the rudder shaft. Turns real sharp now. Had it that way for many years. You will need to exert more force at the helm to overcome the lesser mechanical advantage. My rudder deflects 45 degrees each way. To take advantage of the increased deflection there's a good chance you'll need to make your rudder bigger. Keep the percentage of rudder area ahead and aft of the rudder shaft the same as the original and if you stray in this regard error in the direction of too much rudder area aft. When you modify things you always take the chance you'll discover things you never thought of .. sometimes in a very painful way. I've had good luck w mods but .......

Definitely do jlenord's suggestion and look in the archives. There have been extensive discussions .. good ones.

North Western Washington State USA
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Old 04-17-2015, 01:00 PM   #4
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City: League City, TX
Vessel Name: Pelago
Vessel Model: Wellcraft 3300 Coastal
Join Date: Aug 2011
Posts: 1,005
Do a Google search for:

Schilling Rudder
Fishtail Rudder
MacLear Thistle Rudder

This will get you started in the right direction. There's a lot of available information on these rudders. Be sure to check out YouTube too.
M/V Pelago
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Old 04-17-2015, 01:27 PM   #5
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City: JAX, FL
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Here's a link for a rudder modification that Mike Thompson did on his Defever 40 Passagemaker plus a bunch of other modifications. (His wife, Melissa, has kept his web site up since his passing)

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