My calculated prop slip is a little high @28% ouch. 5600rpm, 1.5 gears, 86mph gps, 34p props. 30' Velocity. Gotta drop the drives lower.Had speedy 2"s TRS now. Is there a prop fix like going to a 5 or 6 blade?
Thread: prop slip 28%
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02-05-2010 06:02 PM
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02-05-2010 06:44 PMWhat's your X now that you've swapped drives?
I wouldn't get too worked up over it- after following your threads about the engine upgrades you're looking to do, those TRS won't survive a weekend. You'll either be in Konrads or doing a 3A conversion by June.
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02-05-2010 07:01 PM
Keep in mind that when you calculate your slip on Bravo I props the stamped pitch is not true. Here is the rule of thumb on them.
From 22P-32P you must subtract one inch of pitch when calculating slip.
From 34P-36P you must subtract 1.5-2 inches of pitch. (These are all over the board when we scan them)
So your slip is really at about 24%.
So that being said you have A LOT of slip. Can you measure how far below the pad the drive is? If you take a straight edge off of the bottom of the pad directly in front of the drive and then measure how far below the centerline of the prop shaft is, please. With this info we can try to get you dialed in. I also agree with you in that you need to be running 5B or 6B props, dependant upon the outcome of that measurement.
JulieWhen you feel the need for speed...Throttle Up!
GO FAST or GO HOME!
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02-06-2010 12:34 AMI wonder why everybody is always concerned about SLIP #........if the speed is ok, the slip realy does not matter , a matter of fact is ..it will safe your trannys on a TRS,SSM set up !!!!!!
Check your slip # @ 35-40 MPH and then u can say WTF !!!!! LOL
But @ WOT and good speed,,,your fine. IMO
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02-06-2010 12:53 AMI agree with Chris. Your TRS's are being pushed way beyond their limitations. Every second of effort or penny you spend on them behind 800's will be in vain. IMO. I would guess the only reason they haven't blown yet is the high slip.
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02-06-2010 12:18 PM
I spray painted the drives with epoxy paint, my paint rep told me he guarantees the paint not to crack. I figure the drives are now bullitproof with that guarantee
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02-08-2010 01:42 AM
I would think with the propshafts 5" below the bottom, and the notched transom, your slip wouldnt be so high. Either way, swinging 34p 4 blades with your power thru TRS, konrads and some 5 blades would be a route i would look into.
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02-08-2010 11:12 AM
When you run a straight edge off of the bottom of a stepped hull, shouldn't the edge span from the transom to the nearest step?
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02-08-2010 01:19 PM
I mesured the distance from the bottom of the boat (6' straight edge) to the center of my gimble helmet as the drives are off and got a mesurment of 18 1/8"
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02-08-2010 04:31 PM
So I want to make sure I understand this correctly. Your going to run 725-825 HP thru TRS Drives? If this is the case.....I am going to POTENTIALLY discourage you from running 5B or 6B props. They are surely not going to help your drives life span. We may need to think a little out of the box on this one. But I may have a few ideas we can kick around. If your going to change the drive let me know.
JulieWhen you feel the need for speed...Throttle Up!
GO FAST or GO HOME!
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02-08-2010 07:26 PM
The drives are not getting changed this year. I have a L+R spare drives. Talked to Steve Stepp re: X dimension and he said 18" from bottom of the hull to drive input shaft centerline is correct.