prop help arneson asd6 donzi 33
 

Can anyone give me prop tips ??
i have one asd6 and one 1721 arneson drive..
the boat is donzi z33 from 89
engines are gasturbines boeing caterpillar 553 giving 490 hp.
lots of torque..
the drives ratio 1;56:1
engine rpm max 4200
engine max torque approx 2000 nm (unsure).
boat weight approx 8500 lbs ??
where can props be found without having to rob a bank ??
i need 2 opposite rotating props..
i have gotten tip of 28-30" Pitch propeller. 4 Blades at the minimum and a 17" diameter !!!!!