Fuel Consumption for CP27

[relamb]

I have the original M12 10hp Universal Diesel in my 1988 CP27.  Can anyone tell me the fuel consumption that it burns in GPH at what RPM?
I've been cruising it at 2000 rpm, and I just now checked the manual and it says the cruising range is 2600-3300 rpm.
What cruising speed and rpm do you typically run?

[atrometer]

My 29' Bayfield (larger and heavier) with the same engine used 1/4 GPH at cruise (85% of hull speed with clean bottom and prop) - range 300 mi. plus on yours.

[deisher6]

Rick:
I have the original M-12 in our 1986 C-27.  I was cruising at 2000 rpm, which produced about 6 mph in still conditions.  A PO had installed a 12XRHX9 prop.

I do not have a good knot meter or gps set up yet, but I have been keeping records of engine hours and fill ups.  I am averaging around 1/2 gallon per hour. Friday I topped off with 4 gallons for 20 hours of use.

I have started cruising at 2200 rpm since reworking the throttle lever and cable.

regards charlie

[BobK]

I cruise at 2200 - 2500 rpm at 5.2 - 5.5 mph.  The engine burns about 1/4 gal/hr at this speed. Any faster I start creating a wake which takes more rpm's for each small bit of increased speed.  At 3200 rpm it runs about 6.2mph but at a lower mpg.
BobK

[relamb]

I don't know what the standard prop was, but mine also has a 2 blade 12XRHX9 prop, I just checked it.
Has anybody tried the magic-marker antifouling idea on their prop?  Getting ready to redo my antifouling paint.
Is it ok to sandblast the prop to clean it?  Barnacles are scraped off, but there's a bunch of those glue rings where they were.  Maybe a dip in acid or vinegar?

[deisher6]

OOPS! I did not specify that the PO installed a THREE BLADED 12XRHX9 prop in Windrunner. 

I have heard that the three blades just produce better flow in the shadow of the keel. 

It would seem to me that they would provide more traction (less slippage) because of the additional surface area, also more drag when not motoring.

I recommend the indelible magic marker, sue the 'Texas' size.  I used fine steel wool to clean the prop.

regards charlie