My wife just loves the 72' 28 ft flybridge Sports Express. I have my eyes on one but before I decide, I have questions about the power set-up. The very kind, Rachel, at the Maritime Museum, stated that originally, the vessel had 245 hp with a 1.5:1 through a 3:1 gearbox and 1410 props in some instances. So, with the 330s and 1:1s, what's my ideal prop size?
Hopefully, someone reading this has had experience with the set-up and will pass along greatly appreciated knowledge. I'm trying to avoid the cost of experimentation. The story goes that the last props on the vessel were 1312s and I have no info as to their performance.
I just ran a few numbers through the Michigan Wheel online calculator. I assumed a few things for the calculations: 35 kts top speed, target RPM at WOT as 4400. Based on that and a 1:1 gearbox the recommended props come out as a 13x12 3 blade or a 12x13 4 blade.
So unless you have a good indication that the top speed with that power should be significantly off from 35 kts then the 13x12 props are most likely at least pretty close to ideal.