Got a set of Revolution 4 props on this morning so I have a direct comparison to the Bravo-1 props I borrowed from ScottC a couple months ago. Here are the results:

32' Scorpion CC (est 8000#)
3/4 fuel 1 person
Yamaha TXXR250 (carb) X 2
Yamaha props: 21" Yamaha saltwater series 3B
Bravo-1 props: 22" early style (pre vent holes)
Rev-4 props: 21" new style w/ vents fully closed
Weather: 80 degrees 80% humidity for Bravo-1, 71 degrees 64% humidity for Rev-4
Water: flat, both days Results for both would be better with a 1 foot chop to aerate the bottom.
Speeds: GPS

RPM / Yamaha 3B speed / Bravo-1 4B / Rev-4 4B

1000 / 6.5 / 7.2 /6.7
3500 / ** / 35 / 33
4000 / 35 / 40 / 40
4500 / 39 / no data / 45
5000 / 49 / 52 / 51.5
5200 / 51 / won't pull / 53
5400 / 54 / won't pull / won't pull

Comments:

- the 3B's won't run at all between 3000 and 4000 as they keep blowing out. Both the Bravo-1 and the Rev 4 will run there, but still blow out pretty easy if you turn or bring up the trim. The Bravo-1 has a slight advantage over the Rev -4 in staying hooked, probably due to the bigger diameter.

- Bravo-1 would only pull to 5000 RPM, the Rev 4's to 5200. Both are a little low as I'd like to see 5400-5500. I want to try to get the Rev 4's running in a little chop to see what they will do before I look at having them modified to get a little more RPM

- The Rev 4's seem best at trim, you can watch the bow come up quite dramatically as the trim comes in. The Bravo-1 seemed like it wanted to bow steer below 4000 RPM with them trimmed full down to stay on plane. The Rev-4 didn't feel that at all.

- It was really easy to tell when I overtrimmed the Rev 4's, as you could hear the hubs come out of the water (?) and open the exhaust to the air and the motors would drop off from 4500 RPM to about 3900. Guess they need the back pressure.

I think I may still be overtrimming the Rev-4's a little as it is so easy to watch the nose come up with trim, so a little more practice may improve the results for them. Also want to experiment with trading tabs (I have the big 28" long K-planes) -vs- trim to control porposing with higher trim at mid speeds.

There really isn't much difference between the Bravo-1 and Rev-4 in the cruise RPM range, the motors really like to run at least 4000 RPM and like to cruise at 4700-5000 if I can afford the fuel (I've seen as high as 55 gallons/hr, usually about 50-52). The Rev-4's are better at 5000 RPM cruise as there is still throttle response left. When the Bravo-1's hit 5000 RPM there is still an inch of throttle left where there is no increase in RPM.

-Greg

Try turning the propellers in if you aren't doing that already. The Rev 4's should ultimately perform better on this boat

They are turning out, stbd clockwise port counteclockwise. Swapping lowers is a pain, last time they were off the mechanic had a tought time to get them aligned going back on.

-g

It shouldn't be that tough.

I'd like to see the results of that particular test.

Likely won't have a chance to try that this year as I probably only have a couple more weeks before it gets put up for the winter. I might be able to swap the 21 Revs for 19 Revs, wonder if that would be a good idea. My prop calculator says at the same speed and slip the 19's would be 5700 RPM, which is a little above the spec 5000-5500 range.

What could I do to the 21's if I want to get about 200 RPM more? Any chance speed would still go up with the RPM?

-Greg

We can wedge and balance the 21's to increase the rpm 100-200. The Rev's are tricky with Labbing. The truing of the propeller I'm talking about should give you a minor speed increase and a acceleration increase.

I'll probably give that a try over the winter, will likely run them as is for the last couple weeks.

Thanks - Greg