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Too much prop slip with 32p 4 blades?

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Old 09-23-2003, 11:53 AM
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Default Too much prop slip with 32p 4 blades?

30' Sonic
2x502 w/ prochargers @640 hp ea.
Bravo1 drives with cones, 1.5 ratio, with 32p Bravo 4 blades spinning out. Stock X-dimention

I plane out @ 2500 rpm. the port prop will slip and rpms will climb to about 3400 just before the nose drops, the starboard will soon follow. If I push harder to plane they will slip sooner. They will continue to slip, after the nose comes down, if I keep the trim all the way down, lots of airation in the wake. When I start to raise the drives, the props will grab, but it still feels like they are slipping. Acceleration is good, but takes a while for speed to catch up with rpm. No, I don't use the tabs.

Is there too much slip or is it just the nature of the beast?

Thanks
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Old 09-23-2003, 12:00 PM
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What is your max speed at what RPM.

Sounds initially like the props need some cup added to them, but I can't be sure without knowing your max rpm.
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Old 09-23-2003, 12:08 PM
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Max rpm is 5300. But for some reason I am only reaching 5000 on starboard and 4500 port. Both earlier in the season were at 5300.
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Old 09-23-2003, 12:20 PM
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Seems as though you have more issues to tend to than prop slippage right now.

what happens when you do use the tabs?
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Old 09-23-2003, 12:27 PM
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I have never used the tabs. It comes on plane fine, except for the slippage, and once on plane, I have never had the need to use them.
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Old 09-23-2003, 12:49 PM
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As far as the RPM issue, have you looked into the check valve theory.
I didnt notice any crazy amount of slippage when we were out. Try Scotts 26, now that boat has some major slip getting up on plan.
Give me a call when you get a chance.
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Old 09-23-2003, 01:18 PM
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Sounds like you have a pretty hight x-dim. If that's the case, then the Bravo 1 prop is going to be the best prop for getting on plane. Adding some cup to the prop will help with planing, but it will also affect the top end. This is something that a prop expert can really help you with. The other alternative would be to get some more setback. Additional setback will put the prop deeper into the water when planning.
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Old 09-24-2003, 07:47 AM
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Pure Energy,

A few questions;
What year is the boat, is it a stepped hull?
Are the props lab finished?
Did you have any prop work done recently?
What was your speed when the props ran at 5300?
What is your speed now?
Do you keep your boat in the water or on a trailer?
Is there any obvious damage to the props?

If the props are lab finished I wouldn't be too concerned about the props slipping when getting on plane. I would be concerned about the difference in rpm between the motors at WOT. A quick way to determine if you have a prop or motor problem is to swap the props from one side to the other and turn the props in. If the problem follows the prop it's a prop issue. If the rpm at WOT throttle doesn't change it's a motor issue. Just be carefull around the docks; reverse will be forward and forward will be reverse! Also, be carefull turning the props in if you haven't done so in the past! There could be a huge difference in stability and handling of the boat at top speed.
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