max prop pitch

[RockysMate]

This question is for those familiar with max prop. 

I had the Sail-craft of Oriental install the new prop.  They also installed 3/4 inch through hull fittings to help the engine run cooler.  I can now cruse at 3100 rpm (wide open) without overheating.  But my top speed is only 6 knots as measured by GPS.   Propeller is 17" three blade.

[POG]

The performance you describe does not sound satisfactory.  But before anything else is said - do you have the standard W40 engine / Paragon direct 1:1 drive gear box / and the RV 10 1:2 reduction V-drive?

What is the pitch on your Max Prop?

Carl
POG - Hull 118

[POG]

I will re-post my reply with a bit more meat to it.  Here goes:

The performance you describe does not sound satisfactory.  But before anything else is said - do you have the standard W40 engine / Paragon direct 1:1 drive gear box / and the RV 10 2:1 reduction V-drive?

What is the pitch on your Max Prop? I am not familiar with this propeller, but I believe that the pitch is adjustable.  If you have the W40 engine etc as described above a 17" diameter with a 12"pitch works great if you are after speed in smooth waters.  You can expect 5 knots at about 1800 revs.  If you are after a bit more power when conditions are challenging I would go for an 11" pitch.

6 knots at full throttle is not acceptable.  You have to pitch up.

I also think that the 1/2" intake for the raw water is under-sized with respect to the capacity of the raw water pump and possibly the requirements of the engine.  However, changing just the thru hull without getting rid of other 1/2" restrictions in the system, such as the oil cooler and the heat exchanger will not achieve anything.

Carl
POG - Hull 118

[RockysMate]

Ralph asked the question, this is Linda, he is in Oriental getting some work done on ROCKY.  I will relay this info to him in a few minutes when I give him his wake up call.  More later....