OEM Prop

[Cadillac-ack-ack]

The motor is a 1962 40 HP Evinrude, This has been on the family boat, a 1957, 14", aluminum Cadillac since virtually new. Though the motor now, and all through it's use by the family, has a short shaft, as a kid I remember it's purchase as little used with originally a long shaft. I'm 99% sure the prop is a stock item but don't know if there would have been as supplied prop differences because of different shaft lengths. It is aluminum, was painted white (a lot worn off) and has absolutely no markings/numbers of any sort. Is there a way to find it's specs? - Pete

 

[jimmbo]

The 40 hp was shipped with several different pitches as standard, they varied as the years went by, as high as 14 inches some years, 13 1/14 other years, and 13 and 12 1/2 other years. Over the years the shape of the blade changed considerably. There were no difference gear ratios, and the no differences between long and short shaft engines. Markings... OMC would put dia and pitch in the hub near the drivepin hole, or sometimes on the edge of the hub that faced the gearcase, and on some it was on one of the blades.
Myself, I would run a 12in or 11 1/2 on that set up

 

[Cadillac-ack-ack]

Well there is nothing on this prop at all. I have really studied it for any markings.It's diameter is just 10". From what I've read about this motor is max RPM is around 4500, and from research here I understand at WOT, max RPM is what I'm looking for. Putting this all together makes me think that the larger OEM props spec'd for this engine must have correspondingly shallower pitches than the smaller diameter ones. Not asking about specific specs here, but is there a general rule of thumb regarding diameters and pitch in regards to top speed, torque out of the hole, as needed for water-skiing, or most economical at slow plane (simply cruising). - Pete

 

[jimmbo]

The engine was rated 40hp @4500 rpm. WOT range is 4000 - 5000 rpm. We used a 12 or 11 1/2 on a 14 ft Skagit with a 1963 40hp Electramatic. A 13 1/4 did give an extra 1/2 mph but it took a bit longer to plane.