More descriptive details please..... How does it behave under sail power?  How 
does it handle under power? is the boat an inboard or outboard?  

Take a look at this page:  
http://www.blumhorst.com/catalina27/catalina-27-rudders.htm

The C27 is a nicely mannered boat when the rig is properly tuned and good sails 
that are properly trimmed.   I can sail my C27 with two fingers on the tiller 
just a couple of inches to windward of the centerline, in winds from 10 knots 
to 35 knots and higher gusts. (That's true before and after I replaced the OEM 
barn door rudder) if I take the time to set the right sail plan.   

If the the tiller violently gets away from you under fully powered-up but not 
overpowered sailplan, you either have an inadequately tuned rig or an 
unbalanced sail plan.  If you're consistently heeling more than 30 degrees, the 
boat is carrying too much sail area  or the the sails are over-trimmed, and 
you' can expect to feel the boat try to round up hard.  Less likely but 
still possible, your boat is not sitting on her lines fore and aft.   Or, 
possibly  your rudder is grossly asymetrical from one side to the other, a 
defect that is emphasized when the maximum foil is too far aft, like the OEM 
rudders.  

Under power, it's a different story.   A little balance area on a rudder is 
generally a good thing under sail, decreasing tug & load on the tiller, but too 
much balance can cause problems when powering in forward with an outboard.  
Balance is not your friend when the prop is pushing water at the rudder.  The 
prop wash from the inboard tends to push her off course when I'm trying to go 
straight ahead under inboard power.   

With the old OEM rudder, my C27 yawed strongly to port, and pulled very, 
very strongly.   That's because of two factors - the balance area on the rudder 
and an asymetry of the rudder foil.  

Backing is always a problem if you let the rudder get too far from centerline.  
The longer the chord of the foil the longer the lever arm and the harder it is 
to keep on course.

Awaiting more info from you....  maybe it's something I've forgotten to mention,

Judy B
1977 C27 TR #3459 inboard
Sailing San Francisco Bay area


 

________________________________
From: RobAdkins <[email protected]>
To: [email protected]
Sent: Mon, March 29, 2010 11:57:55 AM
Subject: [IC27A] a rudder with a mind of it's own

  
hi all,

upon first sailing my c27 i noticed the tiller can get away from me mighty 
quickly if i'm not careful. this was not the case with my old columbia which 
had a keel mounted rudder. i thought a bit, yes it did hurt, and after drawing 
pictures in my head i've come to the conclusion that a small percentage of the 
rudder, on my c27, is foreword of the rudder post. this would explain it's 
violent tendencies to leap from my hand when executing a sharp turn and it's 
equally violent resistance to coming back to center after said turn is 
complete. i'm wondering if anyone has any clue as to why this design "feature" 
exists. it does make the helm more responsive/sensitiv e under sail but while 
under motor it is a definite hazard. any info would be appreciated. thanks-rob


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