[C320-list] Am I slow under power?

[Paul]

I believe that 5.3 knots is slow at 3000 rpm.  "Rough Draft" was running 
slow when I first purchased her.  I had the Tach checked and it was running 
high by only 25 rpms.  I then had my prop turned and added an inch of pitch 
to her.  1 inch of added pitch will reduce your rpms by 200.  It is very 
important that you do not over pitch the prop.  It must still be able to run 
at 3600 rpms under load.  I was able to run the boat at 3800 rpms under load 
which is why I added the 1" pitch to the prop.  I now can run her 5.8 knots 
at 2800 rpms and just over 6.2 knots at 3000 rpm.


Paul Adison
C320 #722
S/V Rough Draft


-----Original Message----- 
From: Nathan Mauch
Sent: Tuesday, April 17, 2012 7:21 AM
To: C320-List at Catalina320.com
Subject: [C320-list] Am I slow under power?

I'm a pretty new C320 owner and I'm trying to figure out whether I have a 
tachometer issue or an throttle governor issue (3GM30F) on my '97 #453.   At 
full throttle, I make 5.3 knots in a dead calm, but my tach is only reading 
2200 RPM, which I know is well below rated max.  However, I've seen my tach 
wander and I'm not convinced it's working properly.
My question is, is 5.3 knots about right for this boat (15X10 prop) at full 
throttle, or is my tach corret and I'm not geting full RPM out of the 
engine?  Reading through previous posts, it sounds like I should be getting 
at or close to hull speed?
Thanks,Nate,S/V Mistral