Prop data for new prop selection

[elkmo]

Been lurking for a few months waiting for the water to thaw to grad some data to find a prop for my new toy. Never imagined props were so critical. So ready to ask the pros and hope I got all the data needed to help advise me to make a informed choice...

Need a stainless prop, with hub or one designed to give with impact. Aluminum's will get chewed up in my area. Looking for a mid range prop, that will allow the boat to stay on plane at lowest speeds. Not specifically looking for hole shot or top end. Had to add my son to hold the tach. (200lbs). I verified the tach prior to the runs with boat at idle.

Boat is a Polar Kraft 1886SE, aluminum MV hull.

Here are my test numbers each are avg of 3 test runs GPS verified:

SOLAS 3 BLADE 12X10 ALUMINUM

Total boat/gear/gas/people etc is weight = 1690 lbs.

WOT RPM = 5610

SPEED = 29 MPH

ENGINE = 2012 MERCURY 50HP OUTBOARD 4 STROKE 1:83:1 GEARS (not bigfoot) MAX RPM RATING IS 5500-6000.

WATER = SMALL CHOP


QUICKSILVER 10.125 X 14 ALUMINUM

TOTAL WEIGHT = 1690 LBS

WOT RPM = 5130

MAX SPEED = 30MPH

SAME ENGINE

WATER = SMALL CHOP

Thanks

 

[jestor68]

Re: Prop data for new prop selection

Since you seem to be doing pretty well with the 10 pitch Solas; I'll recommend the Solas New Saturn(SS) 11-7/8 X 10 for a SS prop.

What is tearing up aluminum props in your area?

If it's rocks, you may be better off staying with the aluminum Solas. It might be possible to cause more lower unit damage using a SS prop.

All modern props use a shock absorbing hub. Some absorb more shock than others before slipping.

Switching to a SS prop should allow you to raise the motor one hole higher, taking full advantage of the SS props performance potential and gaining back what is usually a slight lose in rpm.

 

[dazk14]

Re: Prop data for new prop selection

The Solas should have been the fastest prop, since it was in the power band.

I suspect the larger diameter is scrubbing off speed.

An important question based on requirements... Which prop held plane at the lowest speed? On paper it should be the Solas.

Will raising the motor cut down on impacts significantly? Jestor's suggestion with the larger diameter, will help hold with higher mounts.

The Saturn's prop cupping seems to vary, prop to prop, so hard to say how high you could go.

Do you have power trim? or a "Doel-fin"?

 

[elkmo]

Re: Prop data for new prop selection

Thanks guys.

I beach will be beaching the boat often, so rocks mainly and tree stumps. Will be cruising thru timber often so plenty os submerged stumps. I installed a depth finder so that is helping.

I do have power trim and used it during the testing. The solas held plane much better at lower speeds and the control was better. The solas is not a cupped prop but to what degree its cupped, not sure. I am pushing quite a bit of boat/weight for a 50hp so the lower pitch props performing better seems correct. PolarKraft recommended a 10 1/8 x 15 prop how/why they got that number not sure, as I requested some performance data which was told is not available, but no way will a 15 work.



so

The Solas should have been the fastest prop, since it was in the power band.

I suspect the larger diameter is scrubbing off speed.

An important question based on requirements... Which prop held plane at the lowest speed? On paper it should be the Solas.

Will raising the motor cut down on impacts significantly? Jestor's suggestion with the larger diameter, will help hold with higher mounts.

The Saturn's prop cupping seems to vary, prop to prop, so hard to say how high you could go.

Do you have power trim? or a "Doel-fin"?