Should I change from 2 blade to 3 bladeprop ?

[George Leitner]

With my hunter 310 I also sometimes feel, that 18 Hp is not enough. Does the change from a 2 blade prop(which was standard) to a three blade prop increase the effciency ? Which make and size is recomemended for a hunter 310 ??Thanks and best regards

 

[Bill O'Donovan]

480 comments on this

...in the Archives under Prop AND three-blade AND two-blade. Check it out (and narrow the search by trying "Three-blade prop vs. two")

 

[Larry Watkins]

Prop

George; 18 HP should be plenty for a Hunter 31. I had a Catalina 30 that weighed over 10k pounds for several years with 11 HP and a folding two-blade prop and it was quite adequate. Maybe your current prop doesn't have enough diameter or pitch. What's your maximum RPM under full throttle in flat water/no wind/no current? Check with engine manufac. for suggested numbers. Good luck.

 

[Kevin]

310 prop

Hello George,Your 310 could see an increase as much as 30% in the propulsion efficiency when going from a two to three blade. You can check the current prop by giving the engine, away from the dock in forward gear, full throttle and witnessing the achievable maximum Rpm. In reality the propeller is a governor to the engine. To little diameter or pitch= to many Rpm’s and speed reduction. To much pitch or diameter= not enough Rpm’s or over loading to the engine. Your current two blade, type EA blade, is ok in very flat calm water and is ok in sailing. Add heavy winds or seas while motoring and zap there goes my prop efficiency and my boat speed. Place a three blade in there and the speed loss will be much less per given sea state but sailing speed now suffers a greater loss. The recommended three blade is a 15” x 11” RH 1” shaft. Of coarse this assumes you have the 15” x 12” two blade current. Hope this helps. Kevin.