Propeller recommendation: 14.5' Alumacraft w/Mercury 50HP 2stroke

[Rad Racer]

I have a 1965 14.5' Alumacraft Maracaibo with a 1978 Mercury 50hp 2 stroke OB. The current prop is a 10 5/8" x 12P. The boat weights 450lbs, it has a load capacity of 1070lbs

The boat comes up on plain very quickly w/2 people and I get about 30mph before hitting 5500 rpm's (max rpm). I do not know the WOT rpms because I stopped advancing the throttle once it hit 6500rpms.

I have a 11.1" x 14p prop I plan to try but suspect it's still going to be too small.
Can anyone recommend prop for my boat/motor combo?

 

[cyclops222]

Who picks the props for these overpowered boats ?

 

[Rad Racer]

Who picks the props for these overpowered boats ?

Overpowered?? The 1965 AlumaCraft Maracaibo is rated at 65HP.

https://www.fiberglassics.com/library/images/c/c3/Alumacraftbb005.jpg

 

[cyclops222]

I assumed Alumacraft made Aluminum boats. My error.
Not my error according to the supplied chart. It is Aluminum.

 

[Rad Racer]

I assumed Alumacraft made Aluminum boats. My error.

Alumacraft made both alum and glass boats....the Maracaibo is aluminum.

 

[racerone]

A test run with the 14" will determine what pitch you need.----My wildest guess says 14" will be just right !

 

[Rad Racer]

I switched to the 14" prop.....we are headed to the lake for a test ride.
Thanks for the input, I will let you know how it goes.

 

[Rad Racer]

The 11.1" x 14" prop worked great. With (4) people in the boat it still planed nicely.
With (2) people the WOT RPM's were 5700, still a little high, but not like before.

 

[Texasmark]

Don't worry about the little bit of overage with light loads. Stay with what you bought.

 

[jimmbo]

I think the Tach is reading a bit High. In 50 yrs I have Never seen a 14" prop on the 44. inch 50hp, on a 14-15 boat, turning 5700 rpm. I have seen them turn around 4700-4800rpm

 

[Rad Racer]

Jimmbo, your response got me thinking.

I installed a brand new Faria tach during the build and now question if I have it setup right. After reading and re-reading the documentation, I believe I had the pole setting switch set wrong.

According to the tach documentation the pole count setting on the tach is half the number of actual stator poles. Since I have a 12 pole stator the switch setting should be set for 6 poles or a switch setting of "2". I had it set to "5" which is for 12 poles.

If my understanding of the Faria documentation is correct, I think the rpm reading with a "5" setting would be higher than the actual RPM's.

I will drop it in the pond to verify after Labor day.