[C36IA] prop pitch and engine problem

[tjsoko at aol.com]

Darin,
One of the first things you should do is calibrate your tach.? I have never heard of any tach, on any boat, that was accurate from the factory.? I assume the surveyor used an optical tach?? You can now pick them up for as little as $50, and they are really easy to use.? You should be able to reach 3000-3200 at WOT in neutral, depending on the engine.? If you can't then the tach is off.? The drop of 50 or so RPM from neutral to loaded sounds about right, although I have no idea why the speed is only 4.5.? 

Tom Soko
Julandra #659


-----Original Message-----
From: Darin Duphorne <darinhouston at sbcglobal.net>
To: c36list at c36ia.com
Sent: Wed, Jul 1, 2009 9:57 pm
Subject: [C36IA] prop pitch and engine problem



I'm post-survey, but still pre-purchase of a 2000 C36MKII with a Max- 
Prop 3-blade feathering prop.  I've read enough of the forum posts to  
get an idea what rpm and hull speed I should be getting but it's  
really weird, and I can't tell what might be causing the issue other  
than prop pitch.

In the sea trial, I was only getting about 4.5kts under full power in  
flat lake conditions.  Free rpm was around 2850 and loaded rpm was  
about 2800 (50rpm droop -- not enough).

We asked seller to repitch to confirm, and he's been having a diver do  
it with no success.  Here are the things they've tried...

15x18   4.5kts  2800rpm
15x20   6.7kts  1800rpm
15x18   6.8kts  1900rpm
15x16   7.0kts  16-1700rpm (yikes!)

It's weird!  I can't imagine an engine related issue, or it wouldn't  
get to 2800rpm, I wouldn't think.  Compression problems when loaded?

Any ideas?
_______________________________________________
C36list mailing list
C36list at c36ia.com
http://www.c36ia.com/cgi-bin/mailman/listinfo/c36list

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.c36ia.com/pipermail/c36list/attachments/20090702/74bb5f9a/attachment.htm