X-Rated30

I was wondering... Can't you achieve the same results from monkeying around with both of these. I know there must be limitations, or else some of the people on this board would be running 42" pitch props and others would have big gears attached to 1100 hp motors turning 22" pitch props spinning a gazillion rpms.

What are the limitations?

formula31

Im pretty much alone on this and it is real ancient information but in the 60's and 70's, the guys at Merc who made our hydroplane props told me that the most efficient pitch for a 3 blade was 25 inches. I geared my formula that way and on that boat it ran pretty good. Im sure that advances in propeller design and manufacturing have come a long way since then. BTW, we ran 2 blade props on the hydros then.

Aggressor 25

I hope that I made a good choice in going with the IMCO 1.25 gear for my SC. I have a 7 foot beam boat and want to spin a smaller pitch 4 blade bravo (24 to 26 pitch) to keep the boat from listing to the port side when getting on the throttle. I know I am going to give up some torque, but I would rather go fast "well" then go faster dangerously. I am interested in what others may have experienced with < 1.36 gear ratios. I should be water testing in the next 30 days or so.



I edited the 1.26 to the correct 1.25 gear ratio,
Ty

aero-offshore

Hey Ty, I've got a 7' beam on a 24' boat with the bravo 1 - 1:36 gear and a marage plus 3 blade 25 pitch, under hard excelleration it list so bad I swear its going to roll over.

homan

Try a 4blade it helped my scarab a bit also on the ratios I did some testing and pretty much found about the same speed with a 1:36 21 mirage plus and a 1:50 23 mirage

Beak Boater

Hey Ty
Next time you are going to Fairview Beach remind me to stay on the right side of you!! Sorry not much help we run 1.36 but with 2 motors and Fountains turn inward. Have you tried any 4 blade props?

Aggressor 25

Thanks for the responses...

Last season I ran a 28" 4 blade bravo 1 prop with a standard 1.50 Imco Extreme Advantage 2" shortie with my 502/500 HP.

This season, I have the new Imco SC with the 1.25 gears and it is also a 2" shortie. This is all speculation as I have not splashed it yet, but I think since I am adding a few more ponies that I should be in the ballpark with a 24" to 26" bravo 1 prop. I have not been able to get on plane or cruise with a Hydromotive 4 blade or Mirage since going to the 2" shorter drive. So a prop that bites and carries the bow well is a must.

Has anyone experimented with the Hydromotive P-5? I woulld love to try the new Mercury 5 blade Maximus, but I heard that it was first coming out in 30 and 32"

Beak Boater, I think that was you that quickly caught up with me and a few other Sunsations running North last season from Fairview. Maybe this year I can give you a better run. I think you will be safe on either side since I am not to heavy on the throttle, I like to ease it up there vs. having my drive rebuilt in the middle of the season.

Ty

Aggressor 25

Aero-Offshore,

What are you running for power with that 1.36 and 25" Mirage? Sounds like you have some impressive torque!!!

cobra marty

Have you tried a Left hand prop to counter the engine rotation tQ and help the listing problem. Use a L hand prop and run it in reverse.