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Old 07 May 2008, 07:30   #1
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What is a "bow lifting" prop?

What do the prop manufacturers mean when they say a prop is "bow lifting"? Are they trying to describe a certain general characteristic of the rpm verses thrust curve?

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Old 07 May 2008, 08:21   #2
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It's a prop with a characteristic which causes it to pull the stern down into the water and therefore lever the bow upwards.
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Old 07 May 2008, 10:12   #3
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The idea of a bowlifting prop is to give better hole shot, 4 bladed props for example generally lift the bow more.
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Old 07 May 2008, 14:17   #4
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Do they mean that there is more thrust at lower rotational speed (i.e. more efficient low down) to pop it out of the hole - and does this automatically mean that there is a trade off at the high end?

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Old 07 May 2008, 14:44   #5
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Nope. Normal use is to get the bow lifted at high speed and so reduce the wetted area of the hull in order to reduce drag. It is more common not to require bow lift for getting onto the plane. In some prop/hull combinations using a bow lifting prop requires trimming the drive in to prevent the stern bogging down while the boat is lifting onto the plane.
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Old 07 May 2008, 15:04   #6
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one of these should lift the bow http://www.letsgoseeit.com/index/cou...e37_8in_30.jpg sorry too obvious to miss that one, I'm sure that we will have some more "big ones"
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Old 07 May 2008, 15:37   #7
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Quote:
Originally Posted by jwalker View Post
Nope. Normal use is to get the bow lifted at high speed and so reduce the wetted area of the hull in order to reduce drag. It is more common not to require bow lift for getting onto the plane. In some prop/hull combinations using a bow lifting prop requires trimming the drive in to prevent the stern bogging down while the boat is lifting onto the plane.
I agree with JW. I was getting a little confused with earlier posts relating to grip/holeshot. I have a Merc. Mirage ss prop. which they claim is bow lifting.
My limited experience is trim right in for hole shot and then trim out a little. As I get to about 4000rpm the bow lifts further and the boat starts to balance on the planing pad. The change is very noticable; vibration goes to almost zero and engine changes sound to a purr rather than a roar. Only testing I have done is in smooth conditions and I need more practice to get it right every time including adjusting my trim sensor so the gauge is more meaningful. I think it is going to take a few 100 dollars of petrol to learn how to drive the boat properly.
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Old 07 May 2008, 15:48   #8
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I need more practice to get it right every time including adjusting my trim sensor so the gauge is more meaningful. I think it is going to take a few 100 dollars of petrol to learn how to drive the boat properly.

No guage ever works for me, the best ones are my eyes and ears oh and yes .. my thumb on the button
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Old 07 May 2008, 15:54   #9
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No guage ever works for me, the best ones are my eyes and ears oh and yes .. my thumb on the button
I am sure you are right. however my gauge at present barely moves off the down postion so a little adjustment might help me get a useful reference/starting point.
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Old 07 May 2008, 16:04   #10
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Originally Posted by Bigmuz7 View Post
No guage ever works for me, the best ones are my eyes and ears oh and yes .. my thumb on the button
I am sure you are right. however my gauge at present barely moves off the down postion so a little adjustment might help me get a useful reference/starting point.
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