Three blade prop on O'Day 37cc

[Bill Paul]

Hello, everyone! Oh, boy, are we excited! We just bought a 1981 O'Day 37cc. She surveyed very well (phew!). She had been repowered in 1996 with a 38 hp Yanmar Diesel. The surveyor suggested we may want to think about switching to a 3-blade prop to help power us through heavier wind or seas. We are definitely cruisers, not racers. We will go to a prop shop to get the right prop, but our question for you is this - has anyone here done this? Are there any down sides you can think of? Did I mention that we're excited????Thanks,Bill

 

[Olivier Ruhlmann]

Congratulations!

Yes, there is a ownside to it:Three bladed props perform better:for the same size prop you will increase your range. On the down side you will also increase drag, unless you get a folding prop, which are expensive. My marina is located in a very wind place and coming back required motoring in a wind that often blows 30-40 mph. Our 30hp and our 2 blade prop has proven sufficient to us.No matrer what you do you will not be able to motor faster than hull speed (1.34*sqrt(lwl)). Our engine gets us close enough to it, so I imagine that yours would too. Since you have a little more power, having a three bladed prop might allow you to take full advantage of the extra 8 hp. If you don't plan on mottoring much, investing is probably not worth it, but if you plan on mottoring a lot it might be a good investment.