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Old 18 March 2009, 09:58   #21
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It could be because you have a stepped hull - they like to run flat.

Also prop choice may have something to do with it. Often they run cleaver type props when the engine is high up.
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Old 18 March 2009, 10:21   #22
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I use a 'cyclone' propeller 4blade and pitch 23'
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Old 18 March 2009, 10:46   #23
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It depends on the prop and gearbox and how high you take the engine - you need a low water pickup to get the engine high enough to make a real difference- you also have to factor in that you have moved the engine back, so you can in theory lift it higher the further back you move it.

There are a great number of factors here, and the other thing to bear in mind is that you lose bow lift the higher you raise the engine, you may then need a prop with more bow lift on it to make the best use of the new setup ......... it's complicated!
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When a boat looks that good who needs tubes!!!
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Old 18 March 2009, 11:15   #24
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you are right it is complicated.
The boat has already a build in bracket that is not touches the water. The trim was just a bit higher than the lower position (10%) the gear reduction is 1:85.
( so far before i fitted the power lift I had 55+ knots from this propeller at 5450 rpm)

Could you please explain that?
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you need a low water pickup to get the engine high enough to make a real difference-
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Old 19 March 2009, 08:41   #25
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On gearboxes like the Mercury race boxes the water intake is on the bottom of the nose of the gearbox which allows you to raise the engine without losing water pressure, with the normal intakes on the side of the gearbox they limit the height you can get an engine up to reduce drag.

Fuel consumption would only improve if you raise the engine up high and then throttle back to keep the boat speed the same - if you keep it at wide open throttle, the boat will go faster with more RPM, and may even increase fuel consumption, but you will be going faster!
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When a boat looks that good who needs tubes!!!
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Old 19 March 2009, 16:20   #26
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Thank you.
When I will try it again I will post my news.
3 blade or 4 blade suit better the power lift?
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Old 23 March 2009, 10:10   #27
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Originally Posted by Jorgos View Post
Thank you.
When I will try it again I will post my news.
3 blade or 4 blade suit better the power lift?
It's more a question of what suits the hull - 3 or 4 blades both work with a lifter ..........
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Old 23 March 2009, 14:35   #28
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Quote:
Originally Posted by codprawn View Post
Often they run cleaver type props when the engine is high up.
My Verado was set very high, (which is its correct fitting position) but I was surprised that the standard recommended prop had a relatively normal cupping on it, I experimented with a 4 bladers too and improved certain characteristics, but lost others
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Old 25 March 2009, 05:15   #29
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Originally Posted by Bigmuz7 View Post
My Verado was set very high, (which is its correct fitting position) but I was surprised that the standard recommended prop had a relatively normal cupping on it, I experimented with a 4 bladers too and improved certain characteristics, but lost others
Yes Verados do like to be run high on the transom - our 770 with a 250 ran 64mph and was quite high up on recommendation from Barrus.

Codprawn - Cleavers are run on boats because the hull likes the characteristics of those props, not only because they are high or running a lifter.

My opinion is that the only time to fit a lifter is for racing or when you regularly run in shallow water - pointless for regular leisure use ...............
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Old 31 March 2009, 17:01   #30
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I tried once but i did not ha the chance to see the top speed.
I got an increase on cruising speed ( in good weather) from 38,5 to 40 knots at 4000 rpm and 1liter per mile with the engine low

I will try again this weekend
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