Prop testing results.

[gofastsandman]

Denny was kind enough to bring some props for a little real world comparo.

I have been talking w/ Bobby Soles and he said the alum 3 blade would be of no use because it had been repitched. I wish we had tried it in retrospect.


The boat is an`89 Slacker 20sf. Power is `96 Rude 150 w/ 940 hours.

Full fuel, bimin up, and 2 people. 30 gal livewell was empty.

The variation between upwind and downwind was, as Denny noted, quite consistent so I will only report down wind. I missed a little data, but I feel this will be a good and comprehensive real world baseline for my little friend.

Here are the contestants and the numbers.

Apollo 4bl Mirage + 3 bl Powertech 4bl
14.125x 20p 15.380x 17p 15x 15p

MPH GPS--->
Rpm
2300 11.7 13.2 ---
2500 11.9 15.1 12.9
3000 23.2 23.9 21.5
3500 30.0 28.3 26.0
3750 32.6 30.2 27.3

4000 35.2 33.8 29.6
4500 39.7 --- 32.3
4800 {can`t turn it} 39.0 ---
5300 {can`t turn it} {can`t turn it} 37.7

My wot #s are a little off. The PT and Apollo ventilate progressivly and the #`s are maybe 200rpm too fast. The Mirage blows out hard and immediately.

Here are my thoughts and impressions.
The Apollo had too much pitch and was not proppppperly represented. The Mirage was too much dia. to be proppppperly represented. The Powerech was just about right. Had all things been equal, I feel the numbers would have been far closer.

Again the question remains, how did the Apollo still win top end while having way too much pitch and one more blade?

Cheers,
GFS

[76Red18]

Hey Sandy..It would be interesting to try that apollo with the av plate about 3" above the keel. Denny said something about more height when I met him over here on his trip around the world. Sounds like it hooks up well but needs a little air. I've settled on a stock SST 15 x 15 set about an 1 1/2" above the keel. It's an old style without much cupping on the tip like the SST2 has. It's trailing edge has some cup in it to keep it hooked up. Helps lift the stern also. WOT is around 40 mph @ 5400 well trimmed and loaded heavy.

[gofastsandman]

Thanks Rich,
I am gonna try my old Mich Match 14.75x 17 p and see what I can turn. Robert said he can make magic with it as he knows it well....have to gather more info. Been thinking about an Apollo 4 bl 14.125x 16p also. The PowerTech had a great holeshot, grip, and min plane speed. Easy to modulate.
I think the Mirage needs much more power. It grabs hard, but my 150 can`t spin it up.
I did ventilate the PT and the Apollo a tad on top end.

Rich,
Thanks for the O-ring tip on the T-stats.

Cheers, and thank you Denny! Have a spare again...
GFS

[Bushwacker]

Hey Sandy,

I haven't put the spare 14 x 18 4B Vortex back in the boat, so you're welcome to try it if that Merc splined adapter will fit. May take my boat out Thursday, so you could borrow the Michigan adapter on Friday. Denny

[gofastsandman]

Thanks Denny.
See you tomorrow,
GFS