Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 19-01-2020, 16:05   #31
Registered User
 
VChild's Avatar

Join Date: May 2013
Location: Florida
Boat: Lord Nelson, 41
Posts: 69
Images: 1
Re: QUESTION FOR OWNERS OF FULL KEEL, "BARN DOOR" RUDDER VESSELS

Quote:
Originally Posted by Mike Banks View Post
One might imagine the maximum angle of rudder would be 45 degrees, but in practice it is much less than this. I think what you have is about right. The idea of a rudder is to deflect the stern laterally, not to act as a brake. The bigger the rudder angle, the more it slows the vessel, and the slower the vessel, the less the effect of the rudder regardless of angle.

So--I would leave it alone, if it seems to be working OK. By a Barn Door rudder I take it to mean one hung abaft the keel itself with a cutaway in the keel heel--and maybe the rudder face too, to allow for a propeller.

I hear what youre saying about braking effect and slowing of the boat while in forward motion but Im actually talking about a situation where the boat is stationary in a tight channel in a marina. In this situation the goal is to spin the boat with no forward or backward movement like a spinning ballerina. Im not an expert here but I dont think braking action comes into play in this situation although stalling of the rudder would, hence the Schilling rudder with much higher stall angles.
__________________

VChild is offline   Reply With Quote
Old 19-01-2020, 17:15   #32
Registered User

Join Date: Mar 2015
Location: Adelaide
Boat: Adams 31 aft cockpit
Posts: 142
Re: QUESTION FOR OWNERS OF FULL KEEL, "BARN DOOR" RUDDER VESSELS

irrelevant aside...my old Windrider 16 trimaran has rudder stops at 90 degrees both sides - those are the "brakes"
Only boat I have known to have brakes, and by golly they work very well too (mostly for chickening out off wave faces that require more guts than the operator possesses, but occasionally for collision avoidance in close quarters)!
__________________

mowerandy is offline   Reply With Quote
Old 19-01-2020, 18:22   #33
Registered User

Join Date: Mar 2011
Location: Southport CT
Boat: J/36
Posts: 1,089
Re: QUESTION FOR OWNERS OF FULL KEEL, "BARN DOOR" RUDDER VESSELS

Might be worth asking a naval architect, rather than us armchair admirals, if going from 30 to 35 will make any difference.
psk125 is offline   Reply With Quote
Old 20-01-2020, 14:40   #34
Registered User
 
fish53's Avatar

Join Date: Feb 2014
Posts: 320
Re: QUESTION FOR OWNERS OF FULL KEEL, "BARN DOOR" RUDDER VESSELS

Quote:
Originally Posted by psk125 View Post
Might be worth asking a naval architect, rather than us armchair admirals, if going from 30 to 35 will make any difference.
I have, it's well presented in Dave Gerr's book on marine systems along with my classes at the Maine Maritime academy and as I stated 30 will work but 35 is the max.
fish53 is offline   Reply With Quote
Old 20-01-2020, 15:21   #35
Registered User
 
Bill O's Avatar

Join Date: Jul 2015
Boat: Bruce Bingham Christina 49
Posts: 1,059
Re: QUESTION FOR OWNERS OF FULL KEEL, "BARN DOOR" RUDDER VESSELS

Quote:
Originally Posted by VChild View Post
If that achievable angle happens to be greater than 35 degrees, I would be very interested in looking into getting a Schilling type rudder.
As a scientist, it would be interesting to see how the added 5 degrees of rudder movement to either side made any significant change. If I had to guess, it may not be that significant as you would hope to do the job.
If you want a Schilling rudder on your boat (or a modified version), you'll probably have to make it yourself. Making a new rudder isn't as hard as one would think and most likely you would just do modifications/add-ons to your current rudder to get better lift. Whenever you haul out your boat again, look at Xsection of your rudder, then compare it to what a Schilling rudder Xsection.

We made a new NACA 0010 semi-balanced rudder a couple of years ago and it made a huge difference. It was fairly straight forward and not too difficult. Making add-ons to your rudder should be much easier than making a whole new rudder.


Bill O.
__________________
Bill O.
KB3YMH
https://phoenixketch.blogspot.com/
Bill O is offline   Reply With Quote
Old 20-01-2020, 15:46   #36
Registered User

Join Date: Jun 2019
Location: Ensenada
Boat: 1970 Willard 36 Trawler
Posts: 407
Re: QUESTION FOR OWNERS OF FULL KEEL, "BARN DOOR" RUDDER VESSELS

I see your underbody is almost exactly same as my Wm Garden designed displacement/ballasted trawler (Willard 36). Several sister-ships have modified their rudder to a "Fishtail" or Schilling rudder. Results have been impressive, and I am in the process of having it done as part of a larger refit. I've never heard of them on a sailboat - perhaps there is a drag penalty. But would hopefully solve your close-quarter maneuvering issues.



https://www.researchgate.net/figure/...fig2_281097586


Video showing a single engine power boat spinning. Reliable reports indicate this is not out of the realm of possible, though this boat obviously has a lot of hp driving the prop.






Will try to remember to report back in a couple months when my refit is done. I carry a Perkins 4.236 @85hp, so probably similar to your Lord Nelson 41.
mvweebles is online now   Reply With Quote
Old 21-01-2020, 09:40   #37
Registered User
 
VChild's Avatar

Join Date: May 2013
Location: Florida
Boat: Lord Nelson, 41
Posts: 69
Images: 1
Re: QUESTION FOR OWNERS OF FULL KEEL, "BARN DOOR" RUDDER VESSELS

Quote:
Originally Posted by mvweebles View Post
I see your underbody is almost exactly same as my Wm Garden designed displacement/ballasted trawler (Willard 36). Several sister-ships have modified their rudder to a "Fishtail" or Schilling rudder. Results have been impressive, and I am in the process of having it done as part of a larger refit. I've never heard of them on a sailboat - perhaps there is a drag penalty. But would hopefully solve your close-quarter maneuvering issues.



https://www.researchgate.net/figure/...fig2_281097586


Video showing a single engine power boat spinning. Reliable reports indicate this is not out of the realm of possible, though this boat obviously has a lot of hp driving the prop.






Will try to remember to report back in a couple months when my refit is done. I carry a Perkins 4.236 @85hp, so probably similar to your Lord Nelson 41.
Very impressive video.
Lets us know how yours turns out.
VChild is offline   Reply With Quote
Old 21-01-2020, 09:44   #38
Registered User
 
VChild's Avatar

Join Date: May 2013
Location: Florida
Boat: Lord Nelson, 41
Posts: 69
Images: 1
Re: QUESTION FOR OWNERS OF FULL KEEL, "BARN DOOR" RUDDER VESSELS

Quote:
Originally Posted by Bill O View Post
As a scientist, it would be interesting to see how the added 5 degrees of rudder movement to either side made any significant change. If I had to guess, it may not be that significant as you would hope to do the job.
If you want a Schilling rudder on your boat (or a modified version), you'll probably have to make it yourself. Making a new rudder isn't as hard as one would think and most likely you would just do modifications/add-ons to your current rudder to get better lift. Whenever you haul out your boat again, look at Xsection of your rudder, then compare it to what a Schilling rudder Xsection.

We made a new NACA 0010 semi-balanced rudder a couple of years ago and it made a huge difference. It was fairly straight forward and not too difficult. Making add-ons to your rudder should be much easier than making a whole new rudder.


Bill O.
I'll report back after the autopilot modification. Appreciate all the info.
Thanks
__________________

VChild is offline   Reply With Quote
Reply

Tags
keel, rudder

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Barn Find Corbin 39 Fourseasons Monohull Sailboats 41 22-11-2019 04:17
Bruce Roberts barn find- is it worth it? shayski Monohull Sailboats 49 20-10-2018 08:29
When is "Full" really "Full" SV Sedna Construction, Maintenance & Refit 8 27-06-2017 08:15
Full or modified full keel rudder attached...why not vertical rudder? nematon785 Monohull Sailboats 16 10-03-2017 10:08
Swinging Door vs Sliding Door delmarrey Construction, Maintenance & Refit 8 08-04-2012 18:19

Advertise Here


All times are GMT -7. The time now is 17:42.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.