[C320-list] Prop question

[Scott Thompson]

I'm not getting noticeable black smoke.  On the other hand, it was a 
windy day and with chop the exhaust was in the water a lot.  A hard day 
to see the exhaust clearly in other words.

McCullough, Kirk wrote:
> Scott
> 
> It sounds like it's over-pitched probably. Are you getting any black
> smoke when you are at max rpm under load?
> 
> I just installed a 3 blade Kiwi Prop. It is slightly over-pitched it
> seems, as I can only get to 3100 rpm and could get to 3300 with the 3
> blade fixed. It motors in forward about the same as the fixed prop, but
> is unbelievable in reverse. It has so much more thrust in reverse, and
> backs down straight. Boomerang is much better under sail of course. It
> seems we can point higher, have less weather helm on a beat, and the
> smooth water over the rudder just feels so much better. It accelerates
> much better out of a tack too. And it adds up to a knot of speed in
> medium air.
> 
> I will adjust it the pitch next time I feel like jumping in the water.
> 
> 
> Kirk L. McCullough
> Boomerang #124 
>  
> 
> -----Original Message-----
> From: C320-List-bounces at catalina320.com
> [mailto:C320-List-bounces at catalina320.com] On Behalf Of Scott Thompson
> Sent: Monday, June 19, 2006 7:48 AM
> To: C320-List
> Subject: [C320-list] Prop question
> 
> Sorry to bring up religion, but I've not been very satisfied with the 
> Gori 2 blade folder I installed on Surprise this Spring.  I have not 
> been on the water much, but when I've been out, there has been a lot of 
> vibration and it seems like the engine is working too hard.  I have the 
> 16.5in diameter 11in pitch model, RH drive.  This is what was 
> recommended to me by AB Marine, who arranged delivery after I ordered 
> the prop from Defender.
> 
> I replaced the Catalina factory 3 blade fixed prop.  I have a 1999 boat 
> with the Yanmar 3GM30F.  Yesterday doing sea trials on the Magothy River
> 
> I found I could get the engine to 3300 RPM under no load, suggesting my 
> tach is probably reading a little low.  However, when under way I could 
> not get the tach past 2700 RPM, and there was severe noise and vibration
> 
> at that RPM.  With no obvious current the GPS was reading 6.9-7.0 at 
> this time, with the knotmeter (not recently calibrated) reading a bit 
> less, as it usually does.  The vibration is significant at anything 
> above 2500 RPM, and the engine temp starts climbing over 180 too.  With 
> the fixed prop I could get the tach up over 3000 RPM without any 
> problems.  I had thoroughly cleaned the prop just before this trial. 
> The bottom is not pristine, but was painted just before launch in May, 
> so isn't terrible either, with a bit of light slime only.  I was towing 
> a rigid dinghy in light chop, with wind abeam at the time, and so did 
> not expect to hit full hull speed.  On the other hand, I never had 
> problems hitting max RPM while towing the dinghy with the old prop, 
> except when it was severely fouled.
> 
> I think I'm over-propped.  Any suggestions as to what my next step 
> should be?
> 
> Scott Thompson
> Surprise, 653
> 
> 
> 
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