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-   -   Prop Slip Calculator (http://www.classicseacraft.com/community/showthread.php?t=22780)

Islandtrader 06-05-2011 06:38 PM

Prop Slip Calculator
 
I think this deserves a separate post by itself.

Prop Slip Calculator

77SceptreOB 06-05-2011 06:47 PM

Re: Prop Slip Calculator
 
According to the website calculator mine was 8%. is that good or bad?

Tiny 06-06-2011 12:01 AM

Re: Prop Slip Calculator
 
8%...very good!

Islandtrader 06-06-2011 09:57 AM

Re: Prop Slip Calculator
 
Quote:

According to the website calculator mine was 8%. is that good or bad?

With those numbers you should be out racing :D

Fr. Frank 06-06-2011 11:15 AM

Re: Prop Slip Calculator
 
Quote:

According to the website calculator mine was 8%. is that good or bad?

8% slip is astonishingly good. People pay THOUSANDS of dollars to get a single prop with less than 10% slip at WOT and less than 15% slip at cruise.

Now go run at your favorite cruising speed, and record speed & rpm, and see what your slip is then. A very good prop will have 15-20% slip at cruise. Less than 15% slip at cruise is very rarely heard of, although back when new SS props were $375-$500, I once spent over $700 on a completely custom prop from PowerTech, and got 12% slip at cruise, and 8.8% slip at WOT with Merc 2.0L XR4 V6 on the back of the boat below.

basswacker 06-11-2011 03:26 PM

Re: Prop Slip Calculator
 
mine came out to be 25%

77SceptreOB 07-11-2011 03:19 PM

Re: Prop Slip Calculator
 
I made a mistake. My prop is a 17" not a 15", so my numbers are off. I thought 8% was way too good.

It's now 18%

Islandtrader 07-12-2011 08:37 AM

Re: Prop Slip Calculator
 
Quote:

I made a mistake. My prop is a 17" not a 15", so my numbers are off. I thought 8% was way too good.

It's now 18%

Goes back to the old saying "If it sounds to good to be true... :D :D :D"

eggsuckindog 07-12-2011 05:34 PM

Re: Prop Slip Calculator
 
If and I think it is - my gear ratio is 1.87
Stilletto 19"

Then at cruise 3400 I'm at 14% - 27/28mph

amazingly at 4200/4400 it drops to 10% 38/39mph, it stays about there at WOT
Motors too low also would like to go up 2 holes - only get 5300/5400 would like 5600/5800

Thats also with the Big Ol'Fat Houndog( 100lbs) sitting in the bow with ears a flappin - can't get him back when I go fast either, no matter how many times I try and explain the speed factor and getting the bow up

I have been very happy with this prop, amazing trim response and makes the boat ride very dry - other one was very wet, actually very very wet. Never did the slip before though so guess I'm happier

Beware it is very aggresive and will knock down the RPM, I had a 19 on it and it took off a solid 300 RPM for the same size.

Fr. Frank 07-12-2011 05:58 PM

Re: Prop Slip Calculator
 
Dixon, are you running a 200 or 225 on your MA?


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