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Old 19 October 2003, 14:41   #1
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Jet Propulsion

Read on Internet much concerning water jet propulsion and the advantages of it. But nowhere I can find something concerning the fuell consumption in proportion to propeller propulsion at equal speed. I want to purchase a rib boat, with aluminium keel, of 6.30 m. which has an inboard Steyr diesel engine of 212 hp with such a jet propulsion. Is the fuell consumption much more and what are the possible other disadvantages? Who has experience on this subject?
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Old 19 October 2003, 15:40   #2
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In general jet pumps tend to be a less efficient means of propulsion compared to a propeller drive system. This would mean that in order to get your boat to, at the same speed as the same craft with the same engine with propeller drive you need to use more power (higher revs) on your engine thus using more fuel.
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Old 19 October 2003, 17:26   #3
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This is true, but they are a lot of fum with a 500 hp diesel pushing. Before you all say anything it will be fixed soon!

This steyr boat has it got a costoldi drive?
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Old 19 October 2003, 17:43   #4
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No it's a Twin disc waterjet.
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Old 19 October 2003, 18:15   #5
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they get more efficent the faster you go, flat out they are as good if not better than a prop.
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Old 20 October 2003, 14:09   #6
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Quote:
Originally posted by chrisallse
they get more efficent the faster you go, flat out they are as good if not better than a prop.
And where did you get that from?
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Old 20 October 2003, 14:33   #7
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read a few articles on them i think hull design has a bearing as well.....dont you agree then?
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Old 20 October 2003, 15:00   #8
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Hasn't anybody got some scientific calculation methods to compare jet to propellor propulsion? It must be possible to calculate a hp to propulsion ratio...
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Old 20 October 2003, 15:46   #9
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Hamilton's web page is interesting.

A quote from it,

"High efficiency

Propulsive coefficients as good or higher than the best propeller systems achievable at medium to high planing speeds"
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Old 20 October 2003, 16:25   #10
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Quote:
Originally posted by chrisallse
read a few articles on them i think hull design has a bearing as well.....dont you agree then?
No I don't, and you haven't answered my question. As for Hamiltons web page, you don't suspect that they are a little biased then do you?
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