Harper220

She hangs out down in the prop section quite a bit, but I agree, I'd like to learn all I can since I have two shorties on the way.

It will all come down to trial and error which only amounts to more money...

WETTE VETTE

On my boat when I added the shortie the RPM increased 200 RPM and the slip stayed the same. This netted about 3 MPH compared to the standard length drive. I then re-propped and gained another 2 MPH at close to my original RPM with the standard length drive. I would expect to see an RPM increase unless you completely lose your bow lift leverage and the boat is plowing, then you may lose RPM!

Craig

Payton

Thanks Craig. and everyone else too.

I'm running a non stepped V with a transome notch and staggered engines. My prop shafts now when level are about 3" below the V part of the hull (not the notched out part) that is directly in front of them.
That seems pretty deep to me, is it?

Harper220

Are you running a cat? I hope I don't end up plowing the nose due to no bow lift. Then it's time to go back to the Bravo 4 blades, then I probably won't be able to plane out...

PatriYacht

That doesnt seem too far off Mark. Mine is about 6 inches below and my boat has a notch and boxes. Glad you found a couple of shorties Harper. I found one, so if you know anyone with another -2 Imco tell them about me.

BenPerfected

Payton,
I run a non-stepped V with twins and my prop shafts (when parallel) with the bottom are .75" below the bottom. I get on plane a little slow with Bravo 1's in a 30' hull @ 8,000 lbs. (dry).
I started at 4.25" below (including a 3" spacer) w/27P Mirage props at Lake X. Base line was 97 MPH w/ Imco 2" shorties. Switched to Bravo 1's (same effective pitch; 27p Mirage to 28p Bravo 1). At this point we started reducing the spacers...2", to 1" and then to no spacer. The only significant change was the speed increased each time we raised the drives 1". We ended at 103MPH+. After a re-rig, the following year I tested at .75" below the bottom vs. the final 1.25" from the previous year. No change in speed. In my straight V, 1" below is close to optimum.
Sprague

WETTE VETTE

Yes my boat is a cat and it gets bow lift with no trim at speed. If you need bow lift it is possible the sorties will not provide enough leverage. Ya never really know until you try! Good luck!

Craig

gsmith9898

Do you want to sell the one?

Harper220

Tell me a little more about your setup? Boat, engine, drives, props, boxes ... etc ...

What have you experimented with as far as drives and props?

Marginmn

iTrader: (1)

It really depends on the boat, what X dim is has on it, and so on. I have a 2000 fountain fever that came with a very low X dim from the factory. When I went from standard length sportmaster drives to -2 shorties I picked up 5 mph and the water pressure went thru the roof. I was turning bravo one 30's around 5100 rmp and after putting on the shorties I was turning 32 bravo ones at 5300. The imco's have a larger water opening so I am going to have to install relief valves to get the water pressue back within limits.