SABER28

i must be stupid, i dont get how gear ratio and prop pitch matter if they all equal out in the same amount of water moved. like in a jeep a 31 inch tire with a 3.21 rear end is the same as a 35 inch tire with a 3.73 rear end. same engine rpm gives you the same speed.

should i switch mine? why would saber have used that ratio when the boat was made?

RBeyer

To answer your last question most engine and drive manufacturers pair them based on HP and weight etc. Think of it differently than the tire gear ration thing. Look at it more like a 10 speed bicycle. When you use first gear turning that large 27" wheel is simple, tougher in 10th.
This prop calculator is one of my favorites. Put in your own information and you should get pretty accurate information to include your slip numbers. I hope that and the calculator help.

Propeller Calculator / Prop Calculator

hotjava66

Probably whatever they could get the best deal on lol.
That being said, when these boats were built the selection of props was way more limited than today, and once you ran out of pitch/diameter the only remedy was to spin them faster.

SABER28

did you get a chance to try those lower units yet?

RBeyer

Not yet, just moved, am building a warehouse, and mostly we need some water my way. They have been repairing a Damn and it is too low to boat! A couple weeks. I will post results.

SABER28

that would be great! i'm having mr. gadgets on here rebuild and beef up my bravos. just dont know if i will rebuild the lowers or replace them with short imco's. if they work for you i'll probably try them. please keep me informed!

RBeyer

They finally closed the damn where we are and the water is quickly rising to summer pool levels. Hopefully soon. I will definitely keep you posted.

SABER28

get the bottom of that boat wet yet?

RBeyer

I splashed it once for a shakedown run, 30 minutes. All I can say so far is a little cavitation getting on plane, livable. Not sure if any performance gains yet. Had a couple other bugs to sort out as I also had a motor out over the winter to repair a Drive Guardian.
It might get wet tomorrow and definitely by the weekend. More to come thanks for asking.

RBeyer

Second time out with Imco"s and -2 shorties. I don't love the cavitation when getting on plane, can live with it though. Picked up 3 MPH and 300 to 400 RPM with less trim with a full tank. Still tweaking and adjusting but results are not bad.
Prop slip is 17.7 so thinking maybe a 5 blade should help slippage and cavitation planing.