Prop Slip %

[firekracker50]

Just from sheer curiosity i was wondering what slip percentage you all are seeing in your 721 with 250 motors.
Looking at the setups boat i am seeing guys posting 4%-10%.
That is really awesome. I find 4% pretty much unbelievable, but 8-10% would be really good. THats about the numbers i was seeing from my bullet.
Do these boats really get that low of slippage?

[btsmbass]

Not likely, unless light by yourself. 10% is great, 4% is a little bit of a stretch.

[EdDavisKY]

Mine came out 10% on my '09 721/250ProXS

Prop pitch=27
Gear Ratio=1.75:1
Engine RPM=5800
Actual Speed=76 MPH (GPS)
Prop Slip = 10%

Used Mercury's Prop Slip Calculator
http://www.mercuryracing.com/p...r.php

[alabamaphoenix]

I have a 721 with a Merc 250. Loaded with just me, my best speed is 78.23 mph @ 5850 which is about 8%. Loaded with two people, 75.6 mph at 5700, which is about 9%. I run a 27 tempest plus that has been balanced and blueprinted. It has a considerable amount of addition cup, and it bites!

[clm6741]

you can run the numbers however you want say what you want but based on the best information I had my numbers were this.

79.1 mph (gps)
6200 rpms
24" OMC Raker (croxtonized)
1.71 L2 case

it was around 4.9% slip,

I ran the same prop on my new M2 case
72 mph
6200 rpms
24 " OMC Raker
1.85 gears

same slip about 5 %

I dont give a crap if anybody belives it or not but that prop was and is bad to the bone its just to small now.

P.S. dont give me the "your tach must of been off BS) because I was on the Rev limiter which is 6200 rpms and my engine report this morning said max rpms 6203 rpms. GPS speed and engine report and gear ratio dont lie, the only thing that could be off would be the pitch of the prop because the guy just had it worked by Mark then sold it to me as a 24 and im assuming it is a 24 because it was not quite enough prop even when I had the L2 case.

[btsmbass]

Here's the formulas to get actual speed:

pitch+ 1(for cup) x (engine rpm/ gear ratio)
_____________________________________
constant of 1056

this is your theoretical speed then take:

theoretical speed - actual speed
___________________________
actual speed

This is your prop slip percentage.

[clm6741]

yeah I know hte formula but I didnt add 1" pitch for cup because the prop doesnt have a lot of cup and as I said Im not sure what croxton done to it but it would sure haul A$$........

[firekracker50]

That 24" Raker must have been repitched by croxton to a 25 , only explanation i can come up with. That would be about 8% slip which is awesome! If you factor in Cup that would probably wash out around 10-12%. Same with Alabamaphoenix.

Sounds like phoenix is gets as good of slip numbers as a Bullet, with allot better fishability. Thats amazing

Sounds like a sweet rig. I have to say I loved my Stratos but i think the Phoenix would walk all over a new Stratos. And i love my cobra but if i were in the market for a new boat Phoenix would be really high on my list.
My biggest problem would be deciding on a motor.
I have always ran mercs. I love ProXS motors. But I see good top end numbers with the Etec HO. My buddy had an etec HO on a ranger and had slow holeshot, maybe that isnt the case with phoenix.
I think the Yamaha SHO would definately be on my radar though.

[clm6741]

you use to see good top end number with Etec 250 HO..... the new M2 SLE gearcase is bad to the bone on holeshot and midrange but top end it has lost some. I am going thru this as we speak. Now granted it will dang hard to tear it up.

With my old L2 case I had some top end left in my phoenix. if you notice my numbers that was 79.1 on the rev limiter. If it was a 24 then I needed a 25, if it was a 25 then i needed a bad to the bone 26. Either way the prop and boat had real low slip and ran like a dream at all stages. Now im stuck with the stump thumper on ther bottom of the motor, but on the rivers down here we dont get to run wot for very long runs anyway so it is probably better for me.

[firekracker50]

yeah that M2 has gearing like the merc race lowers. CLE, Sportmasters are 1.87. Thats why the holeshot is better, much better gearing for accelleration.
But you have to turn allot bigger prop, and with that massive lower its gotta have allot more drag.
I have had CLE with 1.87, Torquemaster with 1.75, and Sporty with 1.62.
I prefer the 1.75 on a bass boat. Easier to prop and best of both worlds in torque and top end.