[QUOTE=A.O. Razor;3152407]I have the Alpha One 1.62 gears. Top speed this year so far is 55 mph gps, but it's been lagging lately. I personally think I did better with the 21" Black Max Aluminum, higher rpms and a top end of 57 mph. Less pulling power though.

I'm thinking of trying a 21" Vengeance, which is pretty close to a SS version of the Black Max.

Those can't be accurate tach readings, or you'd be hurting (lugging) your engine. I can spin my 21" Laser at 4900 rpms with my 5.0 engine.

The Rev 4 prop is a beast, and lots of power needed. Rarely does a boat not lose at lease 5 mph with that prop. Immense pulling power though.

A Hi-Five might be a good all-around choice.

Are your speed measured on gps or pitot speedo? 55 mph @ 4200 with the Laser 21" gives you a slip of 1 % with a 1.5 gear. I think the alpha is 1.47 not 1.5, but i could be wrong. That would give the Laser 21" a slip of 3 %, and thas is REALLY low. Your Revolution 4 has a slip of 8 or 9 %. IF the Laser has that low a slip, you don't need a bigger prop. Then you could see 60 with a 19" Laser. No matter what, the Mirage+ will be slower. If you measured the speed with a pitot speedo, then you could be @ 52 or 53 mph 5 or 7 % slip with the Laser, witch seems a bit more realistic. Then a 19" should give you about 57-58 mph. @ 5100 rpm's and the Enertia 20" would be @ 60-61 mph. As far as I remember, 5100 rpm's is where the 350 mag have most power for top speed.

My suggestion would be, to have a Revolution 4 17" for skiing and fun, and either a 19" Laser or, 19" or 20" Enertia for cruising/top end. Do you have a shop near you, that have some test props?

+1 on the hi-five. Nice for skiing and fun.

The reason for the higher rpm's with the alu prop, is that the blades flex, and then you get the rpm's up where the power is, therefore more speed. A Vengance will not flex, so I don't think that is the answer. My personal experience with the Vengance is, that it's a really poor performer compared to ANY ss performance prop. Have you tried a 19"/20" Laser, Mirage or Enertia?

Hello
The speed measured with pitot speedometer. My alpha is 1.47. I will try out your suggestions. To many thanks to for the help!