speedfreak2030
New member
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?
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prop slip 28%
- Thread starter speedfreak2030
- Start date
ThrottleUp Props
Sponsor / Charter Member
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.
Julie
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.
Julie
DAREDEVIL
Banned
I 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
Check your slip # @ 35-40 MPH and then u can say WTF !!!!! LOL
But @ WOT and good speed,,,your fine. IMO
MOBILEMERCMAN
Founding Member / Competitor
I 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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Ratickle
Founding Member / Super Moderator
I don't think your trim cylinders are working properly......:sifone:
inbetween
New member
speedfreak2030
New member
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:sifone:
DAREDEVIL
Banned
HAHAHAHA,,,,,,NICE......lol:willy_nilly:
1000 HP paint !!! hehe:cheers2::sifone:
jeffswav
New member
That must be the magic number of "5". I just cut out my transom this morning and that is were I set mine to. The x diminsion for 5" propshaft depth is 17 1/4". Out of curiosity what props do you run?
MILD THUNDER
New member
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.
ThrottleUp Props
Sponsor / Charter Member
jeffswav
New member
I think that is the picture of Chris's boat, Speedfreak has not posted any pics or given the depth of his drives yet.
speedfreak2030
New member
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"
speedfreak2030
New member
I havn't put them on a dyno but should be 725-825 hp
drpete3
New member
I would bet that he was hoping for better than 83 with 1600 hp. Thats what the big deal would be
ThrottleUp Props
Sponsor / Charter Member
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.
Julie
speedfreak2030
New member
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.
