torew
Gold Level Member 3-2010
Registered: 06/02/08
Posts: 1,129
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| | 02/12/10 at 05:41 AM | Reply with quote | #16 |
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How does it perform with only one motor running?
With twins, you should make sure you are able to plane with only one motor running. If it planes with no problem today, I would try a higher pitched of the same prop, or 22" Raker II
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nkrith
Registered: 04/21/09
Posts: 10
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| | 02/12/10 at 05:44 AM | Reply with quote | #17 |
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It goes on plane with one motor and reaches a speed of almost 28 knots.
I should not go on a smaller propeller pitch but a bigger one.
I had the 22" Vipers and the motors were overevving at the start and almost hittin the revlimiter at 6200. Pitch 22 is out of the question.
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nkrith
Registered: 04/21/09
Posts: 10
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| | 02/12/10 at 06:04 AM | Reply with quote | #18 |
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I also think that the Raker is not produced for counter rotation |
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torew
Gold Level Member 3-2010
Registered: 06/02/08
Posts: 1,129
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| | 02/12/10 at 07:22 AM | Reply with quote | #19 |
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Well, I can just read your numbers: If you get 50-52 knots, a 22" Raker II should work. I have a "detuned" 22" Raker II, now 20,7" (the prop shop measured the difference before/after to be 1,3") and get 50+ knots at 5500-5600 rpm. The Raker is a completely different prop from the Viper, and the pitch cannot be compared directly. The practical pitch is more or less the same as the theoretical pitch. The 22" Raker II should be good for 55 knots without overrevving. I would at least consider it.
Taken from the Evinrude brochure:
"A full line of Hydrus™, SST®, Raker® II, Viper,™ and Renegade™propellers are available for standard and counter-rotation models." Don't know if this means that they have all the props in counter rotation, though |
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torew
Gold Level Member 3-2010
Registered: 06/02/08
Posts: 1,129
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| | 02/12/10 at 11:05 AM | Reply with quote | #20 |
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Quote: Originally Posted by nkrith
It goes on plane with one motor and reaches a speed of almost 28 knots.
rpms with one motor? |
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Huey
Moderator
Registered: 04/20/08
Posts: 3,184
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| | 02/12/10 at 06:05 PM | Reply with quote | #21 |
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Hi, great rig you have now. As for the Raker 2 prop they are not available in LH rotation so they would not work. I do not have any experience with the Hydromotive props but as a rule of thumb 4 blade props do not rutn as many revs as 3 blade prop and the ideal WOT RPM for your engines is 5500-5600, better to be a bit over in a twin rig. If you can I would try the 25 inch RH and LH Rebel props to see what they do.
Cheers,
Huey.
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nkrith
Registered: 04/21/09
Posts: 10
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| | 02/13/10 at 02:00 PM | Reply with quote | #22 |
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I think the 25 inch Rebels is the test i have to make.
I agree with you 100%.
However what i am thinking is that probably i have to reduce the engine position in order to try the rebels since i have been told that they dont work well close to the surface .
I am also gonna repitch The 23 inch hydromotives to 24 inch to get better cruise and consumption and reduce the WOT rpm from 5850-5900 to 5500-5600 with considerable loads
thank you
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