prop slip
04-03-2006, 08:29 PM
#1
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prop slip
I was just going to call and talk to Matt but I thought others would like this topic so I am asking for opinions on target slip percentages ? maybe we should break down into pleasure verses race boats ( obviously a race boat is much more tolerant of ease of planning , mid range cruise efficiency etc) and 4,5 and 6 blade numbers
Larry
Larry
04-03-2006, 10:08 PM
#2
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Re: prop slip
There are previous threads refering to this subject if you want to scroll back.
Years ago, before my time at Mercury Marine, the standard Mercury set was 15% down to 10% was considered perfect numbers for sport boats and performance minded folks. Below that level was considered race ready set ups. Above 15% was concidered ok depending on the application.
Things changed a couple years ago with the invasion of steped hulls, more pleasure cats and 5 blade propellers. People started thinking they should all run 10% slip or less. In my opinion this just isn't true. I remember on this forum, seeing people state, "your slip is too high", when they were running 13% with a 36 Outlaw. Maybe they had a full cabin and a dance floor, who knew!
I believe anybody running under 15% is doing well. Of course the APPLICATION has to be put into perspective.
Slip is subjective. What I mean is, don't always concentrate on it. If the slip goes up and so does the speed, and speed is what you were after, speed wins!!
I have a couple boats running in the high teens slip wise, if we harness the slip, we lose speed......hmmmmmmm?
Great question but, I'm babbling...........................
Years ago, before my time at Mercury Marine, the standard Mercury set was 15% down to 10% was considered perfect numbers for sport boats and performance minded folks. Below that level was considered race ready set ups. Above 15% was concidered ok depending on the application.
Things changed a couple years ago with the invasion of steped hulls, more pleasure cats and 5 blade propellers. People started thinking they should all run 10% slip or less. In my opinion this just isn't true. I remember on this forum, seeing people state, "your slip is too high", when they were running 13% with a 36 Outlaw. Maybe they had a full cabin and a dance floor, who knew!
I believe anybody running under 15% is doing well. Of course the APPLICATION has to be put into perspective.
Slip is subjective. What I mean is, don't always concentrate on it. If the slip goes up and so does the speed, and speed is what you were after, speed wins!!
I have a couple boats running in the high teens slip wise, if we harness the slip, we lose speed......hmmmmmmm?
Great question but, I'm babbling...........................
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Brett Anderson / BBLADES Professional Propellers
920-295-4435 http://www.bblades.com/
[email protected]
Brett Anderson / BBLADES Professional Propellers
920-295-4435 http://www.bblades.com/
[email protected]
Last edited by bbladesprops; 04-03-2006 at 10:11 PM.
04-04-2006, 06:49 AM
#3
Registered
Re: prop slip
Larry,
It's has a lot to do with the boat and it's set up.
In your case, a single engine race V bottom, I want to see 6-8% slip with your 6 blade props. With 5 blade props on your boat I expect to see about 9-10%. Being very familiar with your class these are realistic numbers that you should shoot for. You will also find the best race performance at these slip numbers. You are not setting up a boat for pure top end speed but a compromise that works best on the race course.
For top end speed we would want to make some diameter, pitch and drive height changes.
Now get your boat dialed in for Pickwick and watch out for Randy this year. He has it all figured out and claims he will once again rule the seas.
Talk to you later.
Matt
It's has a lot to do with the boat and it's set up.
In your case, a single engine race V bottom, I want to see 6-8% slip with your 6 blade props. With 5 blade props on your boat I expect to see about 9-10%. Being very familiar with your class these are realistic numbers that you should shoot for. You will also find the best race performance at these slip numbers. You are not setting up a boat for pure top end speed but a compromise that works best on the race course.
For top end speed we would want to make some diameter, pitch and drive height changes.
Now get your boat dialed in for Pickwick and watch out for Randy this year. He has it all figured out and claims he will once again rule the seas.
Talk to you later.
Matt
