4 blades better than 3?

[Wet-Net]

I currently have a 14 x 19 aluminium prop that needs
some rework. It is on a 19 ft Intruder Sterndrive W/ Mercury 4.3L-190 HP V6. I will have it repaired and keep as
a spare. Been checking new props and wondering if anyone
out there is using a four blade prop and willing to comment
on pro's, con's & overall performance vs a 3 blade?

[Starfish]

I've tried a 4-blade and a 3-blade and settled on a 3-blade for my boat. Top end is generally better on a 3-blade. A 4-blade is generally a little better holding in rough water and in turns. But you'll also find variations in performance from material (aluminum vs. SS), rake, cupping, diameter, and blade shape that can change the performance.

[Beefcake]

My last boat had a 3.0L Merc sterndrive. I changed the prop on it from the stock 3-blade 19P to a 4-blade 20P aluminum prop at the recommendation of a Merc dealer (Staff Jennings). I loved it! Better hole-shot because of the 4 blades, and slightly better top-end because of the slight pitch change. I can look up the specs if you want (it was a factory Merc prop, but I'd have to look up which one), or better yet, I still have the prop if you want to try it sometime. I am planning to try it on my new boat, so I'm not looking to sell it, but it would give you an on-water test to make your decision before you buy.

[BrassMonkey]

Give the 4 blade a try. I changeg from a 3Blade to a 4 blade and Love the hole shot.Also keeps the bow down and will even let you trim it higher when running @ WOT.

[Wet-Net]

I'm going to try the 4 blade Mercury Alpha4 14x20
Picked one up on a "Try before you buy" from my favorite dealer, I just installed it and will post my thoughts & impressions after I get back from the water.

[Wet-Net]

Well,
Went out and tried the Mercury Alpha4 14x20,
Aluminium 4-blade prop on my 19ft Alumaweld
Intruder V6 Sterndrive.
With aprox. 30 gallons of gas(1/2 tank), canvas up,
two adults and "Ozzy"(my Black Lab)aboard.
Here are my First Impressions:
A Faster Hole Shot than the stock 3 blade prop.
Continuiously smooth power pulling up on plane.
Roller Coaster like turning W/O cavitation.
Better steering response at low speeds @ 3-5 MPH
A smaller wake was produced through all speed ranges.
Top end speed 44.3 MPH per GPS @ 4200 RPM.
I think I'll try the next pitch up & see what that does.

[BassinFever]

Well,
44.3 MPH per GPS @ 4200 RPM.
I think I'll try the next pitch up & see what that does.



You will be lugging the engine if you do, Your WOT RPM should be around 4500 or maybe a bit better. If anything I would think you should go the other direction.

[Twoshottom]

Thanks for the report Wet-Net. I still need to get a spare prop for my suzuki 140 hp four stroke and appreciate reading these report. :cheers:

[backlash442]

Wow I'm surprised you can get that kind of speed out of your engine. I have the same engine but in a Seahawk. No way can I get anywhere near 40mph at 4200rpm gps or no gps. Using a 3 blade 20p prop maybe high 30's at w.o.t (4800).

I also have a 4 blade 15p for tubing and high elevation. The wake this thing kicks out is much larger than the 3 blade. Kids don't like me to use the 3 blade because of the wake even though I can tow them faster with it. Hole shot is far better with the 4 blade as well as turning. It was never bad but the 4 blade makes you have to hold on tight or you will go flying. Think I'm going to have it repitched to 16 as there really is no top end speed. Still get some cavitation though.