Rebel vs Viper

[606zpx]

Have a 22 deep vee with 250 Etec. The Viper is OK but I can tell is not the best prop. Have tried a Tempest which grabs better and holds plane lower but not much diff in economy or other factors.

I have seen the data posted by Seahorse and others comparing Rebel and Viper in the same pitch on the same boat. Usually the Rebel turns about 300rpm lower at WOT placing the boat outside the best operating envelope (it would appear). Does anyone have data comparing say a Viper to a Rebel with slightly lower pitch on the same boat?

Thanks!

[SEAHORSE]

this is hard to read, so perhaps when I get more time, I'll try to fix some of it. Cutting and pasting from an Excel spreadsheet ain't the easiest, unless someone has some tips for an old fart like me.

This info is from a 20' Ranger Bay Boat with a 150 E-TEC on it.

MPH Compare
Prop 21 Rebel 21 Cyclone 21 Viper 19 Rebel 19 Cyclone 19 Viper 17 Rebel 17 Cyclone 17 Viper
RPM MPH MPH MPH MPH MPH MPH MPH MPH MPH
Idle 2.6 2.3 2.0 2.7 2.2 2.9 2.4 1.8 2.3
1000 5.1 4.8 4.8 5.2 4.6 5.0 4.7 4.3 4.5
1500 6.9 6.5 6.8 6.9 6.4 6.8 6.8 6.4 6.4
2000 8.9 7.6 7.8 8.6 7.6 8.0 8.0 7.3 7.4
2500 21.7 12.8 11.8 20.6 10.0 13.7 16.5 9.3 8.8
3000 28.5 24.5 26.1 27.7 22.5 23.7 24.1 20.5 19.7
3500 35.0 31.3 32.0 33.3 24.7 29.6 29.7 26.3 26.4
4000 39.7 36.2 37.7 38.1 34.0 35.3 34.9 30.6 31.9
4500 44.7 41.9 43.1 42.4 39.2 40.0 39.1 35.9 36.2
5000 49.6 46.5 49.2 47.0 43.5 44.9 42.4 40.7 40.7
5500 5000 48.6 5175 47.9 46.9 48.7 46.5 44.1 44.9
5230 5150 5400 5350 47.5 45.4 47.6
WOT 5625 5710 5925

Slip % 7.5 13.5 11.5 4.3 10.6 6.4 2.8 8.4 7.5

Acceleration to 150 ft.
Seconds N/A 6.80 7.20 6.46 6.35 6.40 6.33 6.10 6.20

Fuel Consumption
Prop 21 Rebel 21 Cyclone 21 Viper 19 Rebel 19 Cyclone 19 Viper 17 Rebel 17 Cyclone 17 Viper
RPM GPH GPH GPH GPH GPH GPH GPH GPH GPH
Idle 0.18 0.18 0.18 0.18 0.18 0.18 0.18 0.18 0.18
1000 0.6 0.55 0.56 0.6 0.5 0.6 0.5 0.4 0.5
1500 2.0 1.78 1.98 1.8 1.7 1.7 1.8 1.5 1.6
2000 4.0 3.27 3.55 3.6 3.1 2.9 3.2 2.5 2.7
2500 4.9 5.52 5.80 4.6 5.4 4.8 3.9 4.6 5.4
3000 5.6 5.31 5.65 5.5 5.0 5.7 5.0 5.2 5.6
3500 8.0 6.68 6.94 7.3 6.4 6.7 6.5 6.6 6.9
4000 10.6 8.67 9.85 9.4 8.3 8.5 8.7 7.7 8.4
4500 13.3 12.65 12.62 12.8 11.9 11.4 11.3 10.7 10.5
5000 15.4 14.13 15.36 15.0 13.8 13.5 12.4 12.7 13.8
5500 5000 15.23 5175 15.4 15.2 15.4 15.0 15.0 17.0
5230 5150 5400 5350 16.0 15.7 19.0
WOT 5625 5710 5925

Miles Per Gallon
Prop 21 Rebel 21 Cyclone 21 Viper 19 Rebel 19 Cyclone 19 Viper 17 Rebel 17 Cyclone 17 Viper
RPM MPG MPG MPG MPG MPG MPG MPG MPG MPG
Idle 14.6 12.9 11.3 15.0 12.0 16.3 13.4 10.0 12.8
1000 9.2 8.7 8.6 9.2 8.4 8.5 10.0 10.7 8.3
1500 3.5 3.6 3.4 3.9 3.7 3.9 3.7 4.2 4.0
2000 2.2 2.3 2.2 2.4 2.5 2.7 2.5 2.9 2.7
2500 4.4 2.3 2.0 4.5 1.9 2.9 4.2 2.0 1.6
3000 5.1 4.6 4.6 5.1 4.5 4.2 4.8 4.0 3.5
3500 4.4 4.7 4.6 4.6 3.9 4.4 4.6 4.0 3.8
4000 3.7 4.2 3.8 4.0 4.1 4.2 4.0 4.0 3.8
4500 3.4 3.3 3.4 3.3 3.3 3.5 3.4 3.4 3.4
5000 3.2 3.3 3.2 3.1 3.2 3.3 3.4 3.2 2.9
5500 5000 5230 5175 5150 5400 3.2 3.1 2.9 2.6
WOT 5350 3.0 5710 2.5
5625 5925

[606zpx]

Interesting data and the best I have seen yet. Thank you very much!

I would have thought that it would be best to keep the motor at the top end of the rpm range but when you compare the Viper 21 against the Rebel 21 and the Rebel 19....it looks like the Rebel 21 is the best bet though it may twist as high an RPM.

Most notably it appears to be on plane at 2500 rpm whereas the Viper does not. The difference in speed and MPG at cruise is robust with the Rebel. Looks like Top end is around the same.

[SEAHORSE]

The Rebel was designed especially for boats like yours for better mpg and efficiency in the mid-range and cruise rpms.

The best way to compare the props is to see what rpm and fuel flow is at 30 mph. Compare at the same speeds, not rpms, for real world data. Graph them out with speed and fuel flow to easily review the results.

[nicknick]

very interesting

I'm swinging a 23 viper pulling apx 5200 revs wot and 53 kts on a 6.5 mtr deep V rib with the etec 200 big block (not HO)

which would be better the 21 or 23 rebel?

Am interested in mid range cruising consumption. This side of the pond at about 8 bucks a gallon and increasing its a bitch.


Nick

[SEAHORSE]

21" Rebel and you might try raising your motor up one hole at a time to get the revs up a bit and run faster.

[nicknick]

Thank you kindly Seahorse

Just got the price from the dealer over here - £500 quid for the 21 (900ish bucks)- just picked myself off the ground

any retailer / on line store that would deliver to UK from over there ???


Nick

[Dae]

Seahorse,

What are the chances you might post the actual Excel spreadsheet with the data?

Thanks,

- Dae