Need more thrust.

Hello,

I have a 9m lifeboat, 3m wide, ~3000kg displacement hull. It has a perkins 50hp@3600rpm, 2:1 gear and a 15"-13" screw.

It is reaching its maximum speed (stern digs in) in still weather, but in moderate waves or headwind the speed degenerates a lot.

I figure I need a bigger prop, and I would like to install an adjustable one. I have my eyes on a three bladed 52cm dia adjustable prop, can I use it with the same engine and tranny?
Will that improve the performance in heavy weather?

Thanks,

Sigurd

 

Oddly, the Surfbaud xls sheet suggests that my pitch on my current setup should be 10, while the local propeller expert says that it should be 13, like it is now.