Yamaha Vs Powertech 13.25x14 Propeller Showdown! Yamaha F70 on a Montauk 17
In this video I pitch (no pun intended) the Powertech 13.25x14 against the Yamaha Performance 13.25x14 Propeller on a 1983 Boston Whaler Montauk 17. Both of these props are mentioned in Continuous Wave as well as Whaler Central anf The Hull Truth forums as being the ideal prop for a Yamaha F70 mounted on classic Montauk 17 hull. I believe the Yamaha prop gets a slight edge on the forums.
Here are the two propellers:
Yamaha Performance 3 MAR-GYT3B-V4-14
Powertech Red 3 13.25x14
I had the rare opportunity to put this to the test. I already had the Powertech prop and was fortunate enough to run into a slightly used but in great condition Yamaha prop so it was game on time for a shoot out!
I'll say this in advance, without adjusting for factory deviations in pitch, the Powertech screw comes in with a negative slip. I understand this is theoretically impossible, but the entire concept of "Prop slip" is theoretical in itself. This I make no apologies for that, I'm just relaying the real life numbers I encountered under identical conditions for both. I do however address a common theory that the advertised pitch from manufacturers may be off. That seems to bring the Powertech numbers more in line with reality.
Powertech-RED-3 13.25 x 14
Pitch AVG RPM
14.00 5835 86066.25
Gear Ratio
2.33 1056 2460.48
Theoretical Speed Actual AVG Speed
34.98 34.6 0.38
Prop Slip
4.21% (Based on raw numbers with 14 pitch)
1.08% Based on changing Pitch in calculator to 14.75
Yamaha Prop MAR-GYT3B-V4-14 13.25x14
Pitch AVG RPM
14 6131 85834.00
Gear Ratio
2.33 1056 2460.48
Theoretical Speed Actual Speed
34.89 33.6 1.29
3.68% Prop Slip
There are three basic numbers you need to calculate prop slip, the RPM, the gear ration of your engine and the speed you were traveling at for a given RPM. I used NMEA 2000 data for engine tachometer RPM's and GPS for SOG (Speed Over Ground)
Here is a good place to get the actual formula or use their online calculator.
https://www.hydrostreamforums.com/pro...
00:00 Introduction
01:20 Powertech 1st Run
03:15 Powertech 2nd Run
04:23 Prop Change
05:30 Yamaha 1st Run
07:54 Yamaha 2nd Run
09:55 Results Who Wins!
#yamaha
#powertech
#propeller