Duo-Prop set - size advice please

[PCUK]

170hp at 3600rpm. 1.65:1 DP-C. Displacement 2.5 tons. LOA 26ft LWL 24ft. Semi-D.
We could do with a starting point for a prop-set please.

 

[[2068]]

Is this Groundhog Day?

Nothing has changed ... how do we escape from the time loop?

http://www.ybw.com/forums/showthread.php?331407-Duoprop-propellers

 

[[2068]]

The most important piece of information, you have not supplied, which is "Current Top Speed".

 

[PCUK]

The most important piece of information, you have not supplied, which is "Current Top Speed".

And of course there is the problem. We don't know. How could we when the boat hasn't been afloat! That's the problem with all these useless tables. With a normal prop' calc it will tell you the top speed, not ask you for it. That's the trouble with Volvo, they expect everyone two have a production line clone.
And yes it is groundhog day or maybe old timers disease day as I'd forgotten about the previous thread which didn't help anyway.

 

[[2068]]

If it were me, I would start by trying to borrow a duoprop set size "A1", if you think the boat might make 20kts+.
But this is just guesswork based on a completely different type of boat, and your drive ratio.
I'm not aware of any proper estimating tools for Volvo duoprops based on boat weight etc. that are available to the public.

 

[PCUK]

Thanks FP