3blade vs 4 blade prop

[tbulhead]

I have a Lund 1800 Fisherman with a 115 4-stroke Johnson which came with a 3 blade prop. I can hit 42 mph when it is calm, but often when Lake Ontario gets those 2-3 foot rollers I am often doing 20 mph so my fishing buddies stay in one piece. Would a 4 blade prop improve the ride when I'm going 20-25 mph on a wavy day on Lake Ontario or not?

[Capt Vince Pierleoni]

There are many different reasons why a 3 blade or 4 blade prop could be better than the other. In your case, the 4 blade prop will not help you "soften" the ride. The prop you have gives you plenty of push, you are slowing down to spare your passengers the brutal beating. In waves like that, a boat is a battering ram. The only way to improve the ride is with more length, or more weight, as your boat already has an excellent hull design for it's size.

[jimski2]

20 MPH is plenty fast. 8 MPH is what you will do when they get the price of gsoline where they want it and you raise your sails.

[Has Been]

My boat came w/ a 15/17 pitch prop. Hit it on a rock & took it to Spinneli to repair & buy a second. On his advise I went to a 15 1/2 / 15 or 15 1/2 diameter & 15 forward per rotation. That prop is what I use now . more of a power prop. Trolls better to keep R's up & Boat does not want to "lunge" forward in the rough seas on LO that we get so often when planned out . Lost about 6 MPH on top end but I did not care. When boat is loaded , less stress on the Engine, just don't redline . Also more presice to adjust trolling speed.

[Jack]

I think if you want to soften your ride you may want to try Trim Tabs or a Hydrofoil .

Good Luck JT

Found this about props.

A 4 blade propeller has more blade area than a 3.

This increased blade area will provide better maneuverability on the low end.

A 4 blade propeller will generally handle weight variations less noticeably than a 3.

A 4 blade propeller will generally come "out of the hole" better.

A 4 blade will run harmonically quieter than a 3.

Because of the extra drag caused by the 4th blade, a 4 bladed propeller will be slower on the top end than a 3.

A four blade propeller will have to be smaller in diameter, pitch, or cup to achieve same rpm's as a 3 blade.

[jimski2]

Unlimited hydroplanes have only two blades, so if you want speed at the top end go that way. If you want trolling speeds, acceleration with a full load, longer engine life, go with the four blade.

[ReelPower]

IMO, the answer is yes. I find that the four blade gives better control in the slop. There's more power available and responsiveness to adjust to the the angle/size of the waves. I feather the throttle alot in those conditions to smooth the ride out and the four blade makes this easier.

15x 15 Powertech stainless on a GM 305/Cobra 22' '88 Trophy hardtop. Heavy rig for its size. Had a 15 x 17 three blade aluminum to start with. Nice for flat out running. Not so nice in the slop and around the dock.