Diameter of Propeller

I want to choose a propeller for a tug with the following particulars:
Main engine power(single screw): 3300bhp
RPM: 600
Gearing rate 1:2
which want to tug a 5000 tonne weight in 6 knot speed. and does not have kort nozzle.
please inform me about the specifications of the best propeller which can satisfy my needs. i want to know the type, No. of the blades, and the diameter of the propeller.
Tnx

 

The most suitable diameter is likely to be the largest you can swing if the shaft and thrust bearing can handle it. How much clearance from shaft to hull?

If you are making a serious request then you need to provide more information on the shape and dimensions of the barge to be towed.

Rick W.

 

tnx alot. but what about the type of the propeller?

 

If you provide the detail on the barge you are towing it will be possible to do a useful calculation.

For a prop spinning at 300rpm, 4-bladed, doing 6 knots and diameter of 3m you will have a bollard pull of 30 tonne. Efficiency will be 40%.

You need to talk to a propeller manufacturer. But no point doing that unless you give some useful detail on what you actually want to tow.

This is the sort of information you need to supply to get a prop sized:
http://www.propellerpages.com/?c=articles&f=2006-08-08_Correct_Propeller

You should also be aware that fitting a kort nozzle would lift efficiency to about 70% for such a heavily loaded prop. Would save a huge amount of fuel if you are doing the tow regularly.

Rick W.

 

Thanks alot for your help dear.