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prop slip question

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Old 05-24-2010, 10:04 PM
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Default prop slip question

what are normal numbers for prop slip on a setup like mine? 1986 formula f3ls, zz4 crate motor, 21p mirage. According to my calculations it looks like about 7% which seems crazy to me. I am used to light outboards where my 29p @ 9.5% slip is pretty good, so it just doesnt seem right that a 4k lb boat can have LESS slip!?!?!
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Old 05-24-2010, 10:25 PM
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we need your numbers.... pitch,rpm,speed,gear ratio
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Old 05-24-2010, 10:58 PM
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21", 45-4600, 57-58mph, gear ration I am not sure of. its an alpha one, seem to have read somewhere its either 1.47 or 1.50
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Old 05-25-2010, 08:44 AM
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Are your speeds GPS and is your tach accurate (86 would be an old tach to be using without vertification)?

Julie
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Old 05-25-2010, 09:47 PM
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no verification on the tach, it may or may not be original, i know its not new lol speeds are gps
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Old 05-25-2010, 09:48 PM
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i know how to calculate slip btw. i just want to know what a normal accepted range is. i have a small out board boat that is pretty well setup, so i know all about prop slip in that setting
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Old 05-26-2010, 09:50 AM
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7% slip in an older single engine straight hull is highly unlikely. I think you need to verify the tach and gear ratio in the drive.
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