Duo-Prop size?

[PCUK]

Would anyone like to give us a rough calculation of the prop-set needed for the following set-up.
Boat 26ft semi-d about 2.5 tons. 22ft lwl approx',
Engine 170hp diesel at 3600
Reduction 1.95:1
Thanks.

 

[neale]

Would anyone like to give us a rough calculation of the prop-set needed for the following set-up.
Boat 26ft semi-d about 2.5 tons. 22ft lwl approx',
Engine 170hp diesel at 3600
Reduction 1.95:1
Thanks.

Hello Peter

It's a bit if a punt, but my Bayliner, 2500kgs, 25ft, planing hull, 170hp diesel, 1.95:1 reduction, max rpm 3800, was good with a5 or a4. A4 gave perfect top rpm but a5 was still in acceptable parameters.

Neale

 

[PCUK]

Thanks Neale, that gives us something to start from.

 

[Beever]

Hi

Thanks Neale, that gives us something to start from.

Hello, I believe you used to own Pershilla. I am in negotiation to buy it but would love to talk to you about her first, particularly fuel consumption and wing engine performance. Sorry for hijacking you thread!