2 blade prop ?

[daytrader]

Will a 2 blade prop F up a gearcase on a v6 if u keep rpms about 6k and below, I use to run one on my inlines and never had any problems, u know, higher vibration and stuff. Thankx, Gary

[150aintenuff]

as long as both blades remain loaded the vibration is minimal compared to that of a 3 blade, it you surface the prop it will destroy the case in short order if the blades begin to unload in the air and load in the water.. questio is why would you run a 2 blade?????? its old tech and i didnt think any 2 blade props were built for the v6 size case.

[daytrader]

Thankx for the reply, Mr partin, thats what I was wondering about surfacing the prop and causing damage. But youd be suprised how fast those old "elephant ears" can be. Thankx, Gary

[150aintenuff]

they are faster because their more eficient through the water a 1 blade prop would be the most efficient design if it coud be ballanced if you didnt surface or trim then a 2 blad would work extreemly well.. back in the day the a 2 blade was a speed prop and the 3 blades were the work or torque prop.

[fastercat]

two blade props are great for inboard boats due two beening under water was the only prop we ran on our flat bottom.two blads on out boards went out a long time ago 3 blads are way better. :D

[WATERWINGS]

...............and now they have 4, 5, & 6 blade props...................

WASSITALLMEAN ??

[stvhelm]

those hydros are running 2 blades and when they get moving that prop is surfaced. why wont it work on a outboard?

[150aintenuff]

inboard hydros have a few vibration resistant items called cutlass bearings that an outboard does not... and a surfaced 2 blade will take out a gearcase relitively quickly.. never said it wouldnt work... just asked him why?????

[SportJ-US-1]

those hydros are running 2 blades and when they get moving that prop is surfaced. why wont it work on a outboard?

The latest deal is more blades for less stress and vibration. Usually anyone running a 2 blade is not competitive. There are no unlimited hydos running 2 blades and haven't in 20 years. I think the drag guys live in a vacuum, the more power thing is what they live by. The tunnel boats have been using the 4 and 5 blades for better than 10 years also.

[stvhelm]

the unlimited hydroplanes and tunnel boats usually run in some nasty water and need the better handling of the extra blades in order to stay on the gas. But I still see 2 blades on those drag hydros running on flat water.

[Raceman]

In the 70's, even AFTER the introduction of the cleaver and the chopper, the two blade (over hub exhaust) was STILL the fastest blade made, and yes we did surface em. They would beat the carrier nut loose and let the whole propshaft/carrier assy. pop out the back. We drilled the gearcases and bolted em to lessen that problem. (I put 4 countersunk machine screws in mine 90º apart) A more serious and unfixable problem was slinging blades. I've never run a 2 blade of comparible pitch on a V bottom back to back with one of today's lab cleavers, but suspect it'd still run with one, or more likely be slightly faster. The 2 blades were discontinued by Merc not because of performance advantage of the other stuff, but rather the problems associated with usin' em. Mercury also made a round ear or elephant eared 3 blade prior to the chopper that was an EXCELLENT blade, but they threw blades off worse than the 2 blades for some reason. These props looked very similar to Mazco's RE3.

[150aintenuff]

it all goes to back to the DaVinci flying mancine.. a screw with a single plane of attack will be the most effecient of all propultion through a medium.. UNFORTUNATLY there is a problem with Ballance and vibration.. so yes a 2 blade is about as efficient through the water as a prop can get.. but it does vibrate and eat up parts when surfaced as raceman said..