prop slip
07-29-2009 | 09:57 AM
#22
Registered
Joined: Jul 2007
Posts: 20
Likes: 0
From: Miami, Florida
07-31-2009 | 08:46 PM
#25
Registered
Joined: Oct 2007
Posts: 1,224
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From: marbury, md
I came up with 11% for my setup. Would this be too hard on my drive or motor. the boat is a 98 25 Active Tunder, with estimated 500hp, 489ci, 1.5 bravo one on a Stellings box with 1" lower spacer, 26 B1 wheel. Prop shaft is 2" below boat. 73mph at 5000 rpm. Im not real sure on the drive ratio, could it be something else?
08-20-2009 | 12:25 AM
#26
Chris
Joined: Sep 2005
Posts: 1,426
Likes: 1
From: Snohomish, WA
I ran my current numbers thru the slip calculator adjusting for the fact its a merc prop and its labbed and my slip is 18%-19% (currently 98.5-99 mph w/32 pitch merc labbed at 6100-6200 rpm's) but still the same I have lowered the wot slip and never had any kind of gain on top of trying a stellings box with neg results and a imco 2" shorty with neg results,Smitty
28% would be pretty high,I would be trying drive spacers and different props until you get the best overall balance of speed and driveability.
28% would be pretty high,I would be trying drive spacers and different props until you get the best overall balance of speed and driveability.
I have done an extreme amount of testing and data recording on different drive depths, and different props on my 28' Nordic Heat, and have determined that it runs faster and handles better with slip numbers in the 14%-18% range.
After spending literally hundreds of hours fretting over attaining low slip numbers (got them as low as 5.2%), I deciced to let those numbers go, and concentrate on overall speed and boat handling. As a result, my boat is now faster, and handles better than ever before.
91-92 mph consistantly. 730hp out of a Whipple upgraded Mercury 600sci
Best speed to date: 94.1 mph, 1.504 gear ratio, 5900 rpm, 30 pitch p5-x labbed by Herring, 15.5% slip
Just my observations,
Chris
Last edited by CB-BLR; 08-20-2009 at 12:32 AM.
