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Old 11-10-2017, 04:43 PM   #1
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Pre-swirl stator

Anybody to try this on his trawler?

https://www.marineinsight.com/shippi...fficiency/amp/

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Old 11-10-2017, 06:19 PM   #2
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I have no doubt that it may work well when clean, but I'm guessing it would foul up fairly quickly losing all of the efficiency gains, especially on a full displacement boat.

It could be protected with Propspeed or something similar, but since it isn't fast moving like a prop, it would still get a buildup and need regular cleaning.

The 2 year payback on investment, may apply to a large frieghter, but not most pleasure boats.
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Old 11-10-2017, 06:39 PM   #3
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Quote:
Originally Posted by AusCan View Post
I have no doubt that it may work well when clean, but I'm guessing it would foul up fairly quickly losing all of the efficiency gains, especially on a full displacement boat.

It could be protected with Propspeed or something similar, but since it isn't fast moving like a prop, it would still get a buildup and need regular cleaning.

The 2 year payback on investment, may apply to a large frieghter, but not most pleasure boats.


Agreed, moreover 10% saving on something eating 1 ton per hour is interesting, on 2 gal per hour, a bit less.

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Old 11-10-2017, 07:47 PM   #4
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I have not tried this yet. It was called a contra-guide when it was invented back in the 30's.
I have however tried a contra-rudder on my lobsterboat. I didn't see any real difference but then I didn't have the proper instruments to detect a small difference. I also had a good deal of fussing to get it so it wouldn't pull to one side at speed.
I also tried a airfoil rudder and and off-set that was not contra (like they had on the PennYan tunnel drives back in the day.
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Old 11-11-2017, 06:14 PM   #5
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I would think that would create more drag than anything else. I know the Navy has used essentially the same thing on Torpedoes to replace one of the propellers, they called it a "propulsor". This is my opinion but I don't think that would provide enough benefit to offset the cost of installing it on my slow trawler.

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