efficiency of jets

[Lex47]

Can anyone tell me the efficiency of waterjets.

Regards
Lex

[Olav]

Lex,

as with a "conventional" open propeller, efficiency of a waterjet depends on the particular operating point. At zero boatspeed (bollard pull condition) efficiency is zero. With increasing speed it rises to a maximum value somewhere in the range of 50 to maybe 60% and then declines to zero again when the vessel approaches a speed at which the jet cannot produce thrust any longer.

You might find the following paper an interesting read (I did ;)): MacPherson, Donald M., "Selection of Commercial Waterjets: New Performance Coefficients Point the Way", SNAME New England Section, February 2000 (http://www.hydrocompinc.com/knowledge/publications/WaterjetPerfCoefs.pdf)

Hope this helps...

[Lex47]

Thanks,

I wil look into this pdf file.
I have got some information that the efficiency will vary between 50 and 56 %.
This depends on the speed. The faster the more efficient.

I keep looking into the matter and will report back.

Lex