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Old 20 July 2005, 15:15   #21
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Country: UK - England
Town: Devon
Boat name: White Ice
Make: Ranieri
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Engine: Suzuki 115hp
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Quote:
Originally Posted by qcamel
I think the point being made is that if you move the engine backward to find cleaner water then you would need to move it back more than a couple of inches to have any effect...
Exactly.

If you have 10" setback, then the areated water will be hitting the prop 0.01234 seconds later at 40kts. Now travel behind any boat at 40kts and see how long the water remains disturbed and areated for. I'm not convinced that the setback will make a tangible difference, even at 4kts, but I could be wrong. Naval Architect or Fluids Dynamics Engineer please!
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Old 21 July 2005, 10:00   #22
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Country: UK - England
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Boat name: SMH Rib / War Shot
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Deeper?

Perhaps setback has the virtual effect of placing the propeller in "deeper" water? Once the water leaves the running surface of the hull it starts to rise again?
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Old 21 July 2005, 15:14   #23
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Country: UK - England
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Make: Scorpion 8.1
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ive got a stepped hull boat too, and it does slip easier than a non stepped boat, i remember graham struggling with tickeld pink (i was the other guy that u beat to buy her!!) could be worth mailing johnny fuller or someone off boatmad if ur solas prop dont work, i thought setback was more to alter c of g but if you can lower the motor into cleaner water at same time then great, i fitted a high 5 to get more grip and it worked a treat.. but i can still only use about half my trim range


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