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drive spacers/cleaner water/slip

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Old 06-19-2002, 08:02 PM
  #11
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I ewas afraid that I may be hitting that wall, the only confusing thing to me is the slip being over 14 percent with hering 5 blade props. I am fairly certian that we can run it up to about 6 on the indicator, but I will verify that with Pat.
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Old 06-19-2002, 10:10 PM
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hey, Ted, good formula. One I prefer, but GPS is SPEED OVER THE GROUND!!! Put it this way...I showed an increase of 10 mph on my Apache running with a 25 knot wind at my back and five knots of current going with me. Everyone on the boat went WHEW!!! Thats GPS for you. Turn the boat around in the same conditions and its all the other way. I'd prefer he used a pressure speedo. As a pilot, I file my IFR airspeed with ATC as indicated airspeed. I could return from Detroit in my plane showing 265 knots across the ground GPS but only 165 on the airspeed indicator for that altitude. The book says 175, so that what I file. All air traffic is travelling in the same 80-90 knot tail wind, so its relative. Good numbers TDan. Jerseyboygoesfast.
 
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Old 06-19-2002, 10:30 PM
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Right! Lower the slip, increase the speed...

... but that's only part of the equation. With reduced slip the motors will be working harder to reach the same RPM.

My guess is as you reduce slip you will also reduce RPM's slightly. The fastest speed will be found at the best comination of low slip and high RPM. Also remember the difference that conditions can make, temp, humidity, surface of the water, weight, fuel load, etc.

My .02.

Good Luck with the testing!
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Old 06-19-2002, 10:44 PM
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Dan for you the wall is simply not there by way of, Thunderstorms DDC Bottom Also there is a fairly large horizontal area down at the keel (as we know nothing supports a load like horizontal areas =really neat things like Lift strips a Pad bottom and your water skis) your only limited by simply the amount of force applied by the Engines and the manner of the accompanying setup

Best Regards
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Old 06-19-2002, 10:55 PM
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Thanks for all the clarification, I am starting to understand all this. I am pretty confident that we can reduce the slip, thus increasing speed. And i know we were right at the rev limiters, even bumpingthem, so if we reduce the slip, reduce the rpms and increase the speed I will be one happy mo fo....

I will keep you all posted, and thanks
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Old 06-19-2002, 11:20 PM
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Your drives are ALREADY too deep, need to get them up a little so you can start spinning the right prop...
 
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Old 06-19-2002, 11:53 PM
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Thunderdan, let's start from the beginning.
What pitch props are you running? What is the setup on the props? Right on right or left on left? Are you running nosecones on the drives, what type of drives are you using?
If trimming drives too high, rpm will increase and slip will increase. Perhaps props are a tad too big. Depending on pitch, I have experienced high pitch props will want to paddlewheel in the water. Maybe if you step down a inch or two in pitch and not trim drives out your slip will be lower, mph will be higher.
Have you tried some Bravo I 4-blades?
Over trimming will raise bow and cause props to slip more.
I have experienced similar problems that you are having and achieved my goal of 103 mph 25' Checkmate.
I hope this helps. Get back and let us know how it's going.
SAM
 
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Old 06-20-2002, 01:20 AM
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Hi all,

Usually you dial-in in an area with flat water. If there is a current use 2 way averages. GPS is the only way to go when a change gives you a half a mile an hour etc.

Ted
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Old 06-20-2002, 02:01 AM
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herring props like to run on the surface not below the water. ssince your is about to crack 100 you might try the new merc lower unit with nose cone built in.. it has no wtaer pickup on it thus creating less disturbance to the prop IE you will go faster and reduce drag. probabley almost same cost as buying drive spacers.

Treadwell
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Old 06-20-2002, 08:57 AM
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Dan, I agree with Treadwellmotorsports, I think the nose cone will help, also check out what this Blue Moon guy says, he also has a valid point, call me on my cell when you get a chance
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