Slip calculator- speed

[Realgun]

Prop slip calculator <br />I love this one.<br /><br />Got my boat finished enough to do speed runs and know whats going on.<br /><br />The tach seems to work fine yea! Hard to find the 20 pole tach's for the older Force motors.<br /><br />Anyway got a reeding on tach of 4600 WOT. Prop is a 15 with a good cup so you use 16 in calculator.<br /><br />Reading on speedo is 32mph. Slip calcs to 9% That seem correct to me as at 15% slip its 30mph. I am happy with that.

 

[phatmanmike]

Re: Slip calculator- speed

1984 sportcraft center console 20'2" x 7'6" 2500lbs empty hull weight<br />1991 johnson looper v6 225 with sea drive bracket<br />600 pounds on a 24" setback from hull.<br />anti-cav plate is 2 inches above keel.<br />40 gallons fuel, 1 group 29 battery, 1 12 pound anchor with chain, 100 pounds misc crap.<br />me 220 pounds, and one red 32 ounce gatorade <br /><br />v hull with pad in back, and very mild deadrise, 10 degrees<br />smart tabs mounted on very outer edges of transom<br /><br />4 blade stainless "renegade" prop 19p x 14 diamater<br /><br />52.0 mph, 5800 rpm,gps verified with engine trimmed out to max, on a semi calm day with 1 foot chop and 10 mph breeze.<br /><br />boat was "chinewalking" at this speed, bouncing from left side to right side an back...<br /><br />im using 2.24 as gear ratio, but im not sure...and im using 49 as theoretical speed...<br /> this boat speed calc says im getting NO PERCENTAGE SLIP. it says that i have a NEGATIVE 6% slip..... <br /><br />is that even possible?

 

[Paul Moir]

Re: Slip calculator- speed

Ought to be 1:1.86 (14:26) on that bad boy.<br />Running the 52.0mph data with a 19" prop, I get 7.5% slip. Which I gather is pretty good.

 

[walleyehed]

Re: Slip calculator- speed

Mike, if it's chinewalking with the tabs, you need to move the mounting lugs back on the tab end of the struts...

 

[phatmanmike]

Re: Slip calculator- speed

only chinewalks when its just me in the boat, but it sure does fly for such a heavy beast.<br /><br />paul, thanks for the info. that sounds more like it.<br /><br />kenny, i think your talking bout placing the tabs at more of a 30 degree angle instead of the standard 25 degrees? moving them downwards with more pressure?<br /><br />right bnow the boat is all apart, motor is in the bed of my truck and transom is getting some new wood and glass, so testing will be a while. thanks guys.<br /><br />and thannk YOU, mr.realgun !!!

 

[Realgun]

Re: Slip calculator- speed

Anything for the cause.

 

[Realgun]

Re: Slip calculator- speed

I need a cheap 115 that 85 is ok but I feel the boat can go way faster. That USCG 180 degree wheel turn test barly unseats the boat and you can do a full turn of the wheel at WOT and thats fun! The boat really handles well and rides good to had a 1-2 foot chop and the boat barely notices it. Ok it notices but its nice.