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Too high of slip # suggestions?

S

strehl

Member
Basic setup:
81 exciter, slightly massaged 200hp 2.4L merc., 1.87lwp lower unit, 23" trophy plus worked by dah, 5.5" cmc hydraulic jackplate, and sea star pro steering.

I think that covers the basic. My best speed so far was 75 mph running with the wind in about 10-12" chop even with the pad and tach somewhere in the 7900 rpm vicinity. That's 18% slip. The lowest slip number I could get was 68 mph 6-8" chop ~1.5 below the pad and 6800 rpm with a 14% slip.

I've tried my 26" laser2 at 1.5 below the pad at 6100 rpm and 69 mph but that still at 14% slip. This prop blows out bad while trying to get on plane and just feels really sluggish throughout the rpm range and I can't get the bow lift out of it. Plus the boat is a handful to drive with it.
I've tried dropping farther below the pad but slip stays the same and speeds drop. I'm at a loss at what to try next.
I also can't stay on plane below 28 mph either which kinda sucks when I get stuck following a slower boat in a tighter part of the lake. So I'm guessing a can't do more setback without making that worse.

Anybody have any suggestions?
 
Yeah I don't think I'd leave it at 7900 RPM too long.

Slip numbers don't matter all that much . Its what makes your boat fastest that does matter. A laser II isnt going to be that prop. A good 26 pitch chopper should put you at 80 MPH plus at an inch over the pad with 10% or less slip.
 
Should I look for a big or small ear chopper? I also can't go up any higher than even with the propshaft. I'm all the way up with the plate and engine is bolted as high as i can on the plate.
 
Does your vessels attitude resemble Wired's avatar at speed? Compare engine height, trim angle, and amount of wetted hull. Do you start out with engine down and raise up as speed increases and also use trim angle to lift bow at start. Is hull nice and dry in the interior, water is heavy.
 
Jimway said:
Does your vessels attitude resemble Wired's avatar at speed? Compare engine height, trim angle, and amount of wetted hull. Do you start out with engine down and raise up as speed increases and also use trim angle to lift bow at start. Is hull nice and dry in the interior, water is heavy.
Click to expand...

I'm not as fast as Wired. With a bigger boat so I have more hull wet than he does. I generally leave the jack plate at the same setting from idle to wot. As far as trim I trim down to plane then up to air out after on plane. I doubt the foam under the floor is dry in the back. But I'm already working on lightening and replacing the transom on my entice so I'm leaving this one be.
 
Time to start moving stuff around and getting that prop centerline up as high as possible which means higher than you have it now even if that means changing some gear. Nose cones, jack plates, riser plates etc. How fast can you afford to go?

You need a big ear chopper. I run all kinds of props but the old stand by best all around performer is always the tried and true 26 pitch big ear. It is Mercury's perfect prop. Ive got faster props and props that handle chop better and props that pull harder but the best all around is the 26 pitch chopper.
 
I'll have to start putting money aside for a chopper then. I just found a 25 trophy plus worked by dah locally here so that will at least bring my rpm down to a more manageable level while I find more money for a big ear chopper. I also have a call into DAH to see what they have.
 
strehl said:
I'll have to start putting money aside for a chopper then. I just found a 25 trophy plus worked by dah locally here so that will at least bring my rpm down to a more manageable level while I find more money for a big ear chopper. I also have a call into DAH to see what they have.
Click to expand...

You may run into a problem with the trophy plus porpoising if you dont have the power to get the boat up in the air which is where the trophy will put it.
 
All these through hub props jacked up high are most likely causing the high slip numbers.

I would try to keep the rpm's around 6500 tops if it was mine. :thumb:
 
The 23p trophy would only porpoise with a heavy load or when I force it to porpoise by too high of trim and too low of speeds. I'm hoping with this 25p trophy that I found last night my rpm will come down to a more reasonable level.
John at DAH told me he can drastically improve my 26 laser2 to fit my needs. I might consider that too. How does a chopper handle heavi er boat loads?
 
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