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Originally Posted by Griff
(Post 4874367)
It can be really hard to tell if prop has had work done and it should be if the prop was done right. It could have just been balanced, trued up the pitch and polished.
I'd wait for BBlades winter special. Deduct 1" of pitch for Bravo props for calculating slip. They are stamped heavy compared to actual pitch. Prop slip still way high. What are your WOT speeds/rpms?? We are typically running 40-42GPS @ 3500RPM, and 75-76GPS at 5100RPM, WOT and trimmed to the ragged edge. With the new prop, we were in the 33-34 GPS range at 3500RPM, and high 50s GPS at 5000RPM, but WAY off the WOT position on the throttle arm. I did not stick it or bother trimming it out. I've heard that a 28P Bravo, for example, will run about like a Hydromotive 26. Is this because Hydromotive is a bit more honest about their pitch declaration? Thanks. Brad. |
I ran 46-48 with a box stock bravo 26 at 3500rpm.
I ran a mercury labbed bravo 28 and i can't remember the actual mph was it was definitely higher than the 26. Something is way off with your new 28. |
Guys,
I think I found it: Trailing edge cup. Trying my best to duplicate measuring method and target points…..https://cimg7.ibsrv.net/gimg/www.off...6be185fe6.jpeg https://cimg8.ibsrv.net/gimg/www.off...49d95773e.jpeg Can you tell which one is faster? The older prop has an “X” marked in Sharpie on the hub, right above the “Bravo”. You can also easily feel the distinct reduction in cup in the last half inch or so of the trailing edge of the newer, slower of the two props. Also found this: https://cimg9.ibsrv.net/gimg/www.off...98a5ee609.jpeg Is that a BBlades documentation number? Thanks. Brad. |
Yes, that is a BBlades labbed serial number and they keep all the specs on file.
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Originally Posted by Brad Christy
(Post 4874409)
Griff,
We are typically running 40-42GPS @ 3500RPM, and 75-76GPS at 5100RPM, WOT and trimmed to the ragged edge. With the new prop, we were in the 33-34 GPS range at 3500RPM, and high 50s GPS at 5000RPM, but WAY off the WOT position on the throttle arm. I did not stick it or bother trimming it out. I've heard that a 28P Bravo, for example, will run about like a Hydromotive 26. Is this because Hydromotive is a bit more honest about their pitch declaration? Thanks. Brad. |
Your cruise and WOT numbers with the original prop are very similar to what my 28 Pantera was, except I was turning a custom labbed 26 and was a couple mph slower across the board
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Griff,
Originally Posted by Griff
(Post 4874502)
Yes, that is a BBlades labbed serial number and they keep all the specs on file.
Originally Posted by Griff
(Post 4874503)
Propslip is in the ball park of where it should be with your original prop at about 15%. Mid teens is normal for larger single engine V's
Originally Posted by Griff
(Post 4874504)
Your cruise and WOT numbers with the original prop are very similar to what my 28 Pantera was, except I was turning a custom labbed 26 and was a couple mph slower across the board
Thanks. Brad. |
Originally Posted by Griff
(Post 4874503)
Propslip is in the ball park of where it should be with your original prop at about 15%. Mid teens is normal for larger single engine V's
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Originally Posted by liberator221
(Post 4874526)
Griff, running his cruise numbers it shows about 30% slip but WOT is around 15% like you said. Is that typical? Less slip at WOT?
Makes sense to me. Less boat in the water, the faster you go. Don’t know it that’s the physics behind it or not, though…. |
Originally Posted by liberator221
(Post 4874526)
Griff, running his cruise numbers it shows about 30% slip but WOT is around 15% like you said. Is that typical? Less slip at WOT?
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