Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 09-05-2016, 14:18   #16
Registered User
 
deblen's Avatar

Join Date: Oct 2014
Location: Grand Manan,N.B.,Canada N44.40 W66.50
Boat: Mascot 28 pilothouse motorsailer 28ft
Posts: 1,400
Images: 1
Re: Looking For Thoughts On Building A Balanced Rudder

Quote:
Originally Posted by cottonsail View Post
Here's what I did to get a balanced rudder. The boat turns like a fin keel racer, backs up with control and has a light helm.

Nice job! If you find you are catching rope or other junk,consider adding a "shedder",similar to what I did. / Len

Click image for larger version

Name:	<a title=Rope shedder.jpg Views: 66 Size: 431.3 KB ID: 123985" style="margin: 2px" />
__________________

__________________
My personal experience & humble opinions-feel free to ignore both
deblen is offline   Reply With Quote
Old 09-05-2016, 14:20   #17
Registered User

Join Date: Jul 2007
Posts: 35
Re: Looking For Thoughts On Building A Balanced Rudder

It's about 7% of the total area. That's what you want ahead of the center-line of the rudder shaft.
__________________

__________________
cottonsail is offline   Reply With Quote
Old 09-05-2016, 14:52   #18
Registered User

Join Date: Jun 2015
Posts: 1,164
Re: Looking For Thoughts On Building A Balanced Rudder

Cottonsail has it right. If you're gonna do this at all, the Cottonsail method avoids the need for structural modifications, and it adds area to the control surface. If you tag on a "tip section" like this, the internal structure of the existing rudder will be quite up to handling the addition area.

A consequential problem is that lines from people's crab pots and other such can not slide harmlessly off the bottom of the rudder when you snag them - as you will :-) - but will stick in the gap twixt skeg and tip section. That would be a problem for me. I don't enter water unless I can see the steam rising from it ;-)!

As for a NACA ( National Advisory Committee on Aviation, ca. 1928) "foil", there are dozens of them, and none of them are intended to "back up". Aeroplanes don't back up while they are in the air. The hydrodynamics of the flow around the rudder blade will shift so drastically when making stern-way that considering any particular "foil" a waste of time given how little time we spend going astern.

TrentePieds
__________________
TrentePieds is offline   Reply With Quote
Old 09-05-2016, 15:02   #19
Senior Cruiser

Cruisers Forum Supporter

Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 17,314
Re: Looking For Thoughts On Building A Balanced Rudder

I have built a balanced rudder and placed to much area fore. Avoid this common and stupid mistake.

If you have a skeg, the easy way is to add area below and fore of the axis BUT this sort of contradicts the protective purpose of the skeg, should you touch bottom.

Is the tiller heavy on your boat? Why do you want a balanced rudder?

We have a non balanced one and it is extremely light in all conditions. And your boat is not that much bigger than ours.

Look up Jeffa white papers they show plenty of building details. Great stuff from a great company.

b.
__________________
barnakiel is offline   Reply With Quote
Old 09-05-2016, 15:07   #20
Registered User

Join Date: Aug 2011
Location: West Sussex, United Kingdom
Boat: Tradewind 33, 33 foot, Parker 27 , 27 foot
Posts: 98
Re: Looking For Thoughts On Building A Balanced Rudder

I agree with Fou Fou, 18% is way to much. I have a balanced rudder on my Parker 27 which has a hinged lifting rudder. When I first got the boat it was very twitchy, when I got the boat out of the water at the end of the season, I found the rudder blade was able to hinge to far forward and over balancing the rudder. I fitted an adjustable stop on the lower pintle and after some trial and error, found the perfect sweet spot which turned out to be at 10 area forward of the hinge line. Subsequent checking of the specifications showed this to be where it should be. I have the slightest amount of weather helm which is desirable so that the boat will round up (slowly) if the tiller is left unattended, ie if I fall overboard as I mostly sail singlehanded.
__________________
Martkimwat is offline   Reply With Quote
Old 09-05-2016, 15:19   #21
Registered User

Join Date: Jul 2007
Posts: 35
Re: Looking For Thoughts On Building A Balanced Rudder

Nation advisory council on aeronautics.
__________________
cottonsail is offline   Reply With Quote
Old 09-05-2016, 16:49   #22
Registered User
 
four winds's Avatar

Join Date: Oct 2010
Location: Wandering the US Gulf Coast
Boat: 78 Pearson323 Four Winds
Posts: 2,136
Re: Looking For Thoughts On Building A Balanced Rudder

Brad, I did what you are considering about a year and a half ago.

Could not be more pleased with the results.

Details here:
Rudder Mod - Full Skeg to Partial
__________________
Life begins at the waters edge.
four winds is offline   Reply With Quote
Old 09-05-2016, 19:50   #23
Registered User

Join Date: Jun 2015
Posts: 1,164
Re: Looking For Thoughts On Building A Balanced Rudder

Cottonsail: Quite right! 1928 wuz a helluvalongtime ago :-)

It may be of interest that for a marconi-rigged Seabird (the Mower/Day job from 1901) badly in need of new canvas I built a mainsail - eons ago - that actually had "Clark Y" upper surface coordinates when it was full of wind on a close reach. Worked wonders for the boat. The secret is in the mitre-seam :-)

Might do a mod for TrentePied's main when I rip off that silly Facnor mast furling device. Pity to waste all that luvverly new dacron :-)

TrentePieds
__________________

__________________
TrentePieds is offline   Reply With Quote
Reply

Tags
rudder

Thread Tools
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
How 'well balanced' is your tiller micheck Construction, Maintenance & Refit 12 12-12-2011 18:28
Opinions on the Sig Marine Balanced Draft Flue System cburger Construction, Maintenance & Refit 0 27-10-2011 12:22
Must a Prop Shaft Be Perfectly Balanced ? Shanaly Propellers & Drive Systems 9 14-10-2011 11:22
Pool Navy Anchor - Balanced vs Unbalanced Singleprop Anchoring & Mooring 4 20-05-2011 21:34
Tuning a Balanced SSB Antenna With a Long-Wire Tuner Bint al Kham Marine Electronics 12 28-02-2011 06:20



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 23:37.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.