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Old 10-23-2015, 11:30 AM   #41
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It takes 21hp to push boat at 7kts with 130kg drag: 6.19hp/kg.

20kg of drag from freewheeling prop = 3.23hp loss.

If 18hp burns about 1 gal so thats about 0.18 gal loss.


Maths is not my strong point. Lol.

Anyone like to make up the numbers for twins ...
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Old 10-23-2015, 12:39 PM   #42
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Rusty,
It sounds like you're directing the prop drag info at me. Don't know why if true as I have never contemplated or otherwise supported running one engine on a twin and draging the prop locked .. or freewheeling.
We were talking about shaft drag before but not the props.
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Old 10-23-2015, 12:45 PM   #43
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Quote:
Originally Posted by manyboats View Post
Rusty,
It sounds like you're directing the prop drag info at me. Don't know why if true as I have never contemplated or otherwise supported running one engine on a twin and draging the prop locked .. or freewheeling.
We were talking about shaft drag before but not the props.
Sorry, wasn't directed at you.

I've never seen actual numbers for the amount drag a prop produces, only guesses.

Its very useful to know about 3 1/2 HP......
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