Which prop to run to save fuel?

[CoveSeeker]

Michigan Wheel SS 14.5 X 15 pitch 3 blade #03-3002
OR
Solas Amita 4 blade aluminum 14.6X 15 pitch

wot range 4200 to 4600, 5.7 ltr, 210 hp
boat weighs about 5200 lbs. 22 ft express cruiser Bayliner

Test results:
The MW SS 3 blade
38 mph (gps) 4400 rpm at WOT
28 mph 3500 rpm

Solas 4 blade alum:
37 mph at 4400 rpm at wot
28 mph at 3500 rpm

Both plane in about 5-6 seconds.
BTW the MW SS prop is very heavy--does this extra weight make it harder for the motor to spin it?
Thanks,
Paul

 

[walleyehed]

Re: Which prop to run to save fuel?

Sounds like the MWC SS has some blade wear...
If both produce the same speed at the same cruise RPM, the fuel economy will be the same, if I understand your question correctly.

 

[CoveSeeker]

Re: Which prop to run to save fuel?

Kenny,
thanks for the response--that does answer my question on fuel economy. The guy that sold me the MW said it was like new/never been in the water--could it be that it performs as it does because it's an older obsolete model prop? What is the effect of blade wear and can it be repaired?
Thanks again,
Paul

 

[walleyehed]

Re: Which prop to run to save fuel?

Yes, if it's an older model, it's also older technology....
Blade design can play tricks on ya too.

 

[Texasmark]

Re: Which prop to run to save fuel?

Well I did my own test and if I were in the cruising attitude, around 20-30 mph, the Hustler aluminum would give me the best performance/economy. Just stay away from WOT.

But if I want to blast out, the Ballistic gives me the best performance at 80% to 100% WOT.

Now you have to factor in your engine's efficiency at those two points to get the whole picture which I haven't a clue other than generalities.

Probably the best overall is 80% of WOT, which on my boat (running the 24P XP Ballistic), is 4480 rpm's and 40 mph.

Since I have a pad I am sitting nicely on it (minimum hull drag) and the engine is just loafing along.

Mark