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Old 17-08-2015, 07:00 PM   #1
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Extreme

Can anyone help, I have a merc 525 efi going in a extreme 24 and want to put a Bravo 3 leg on it. What ratio will be best for it 1.50 or 1.65 with what props? Thanks
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Old 17-08-2015, 08:28 PM   #2
bor
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why do you want to put a bravo 3 on it ?? you gonna put in a fast motor then you want to put a bravo behind it but keep in mind that mercruiser put a xr drive behind for the hp and tq !
The ratio you want a 1:50 in that application .
I would start whit a bravo 4 prop if you have any idea of speed you can calculate the pitch you should start whit

cheers

bor
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Old 18-08-2015, 09:25 AM   #3
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The higher the numerical ratio is, the faster you'll go, the theory being A slower turning prop with more pitch is more efficient than a faster turning prop with less pitch.

In reality, the theoretical top speed is the same, but the handling and acceleration may differ.

The difference between 1.36:1 compared to 1.5:1, or 1.5:1 to 1.65:1 is about 2.5" of propeller pitch. So if a 25" pitch works on the low ratio, then a 30" should do the same job on the highest one.
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Old 18-08-2015, 02:26 PM   #4
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Country: U.K.
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Boat make: Extreme 24
Engines: Mercury racing 525
Cruising area: Solent

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Quote:
Originally Posted by bor View Post
why do you want to put a bravo 3 on it ?? you gonna put in a fast motor then you want to put a bravo behind it but keep in mind that mercruiser put a xr drive behind for the hp and tq !
The ratio you want a 1:50 in that application .
I would start whit a bravo 4 prop if you have any idea of speed you can calculate the pitch you should start whit

cheers

bor
Thank for the reply
I have been out in a couple of extreme with duo legs and they are so much more stable than a single prop even with trim tabs.
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Old 18-08-2015, 05:01 PM   #5
bor
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Country: netherlands
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Interests: everthing what s fast
Boat make: p21,32 hustler
Engines: 408 v8 bravo 1x
Cruising area: ijsselmeer

Join Date: Jan 2008
Location: uithoorn
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Quote:
Originally Posted by paul180289 View Post
Thank for the reply
I have been out in a couple of extreme with duo legs and they are so much more stable than a single prop even with trim tabs.
That might have to do something whit drive height if its deep the prop have more leverage to the boat and it will chine walk more ,whit the duo props it s gone because they turn either a side .
I run a imco -3" shorty on my 21 phantom no tabs and have almost no chine walk at 96 mph whit a single bravo 4 blade prop ,If I put a regular bravo drive on it its a handfull to steer the chine walk out .

the duo prop will reduce your speed pretty much which is a shame when you put a 525 efi in I think .
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