2 blade props?

[mellowyellow]

my 16' bowrider with merc 1150 came with the<br />origional 2 blade merc prop, but since it was<br />pretty beat up, i never ran it and went out and<br />got a new 3 blade. were these 2 blades used<br />in the early 70's for a reason? not unhappy with<br />the 3 blade, but curious about the 2 blades...<br />was it a "speed" prop?<br />TIA,<br />M.Y.

 

[snapperbait]

Re: 2 blade props?

"Speed prop", yup... Theoretically the fewer the number of blades, the more effecient the propeller is supposed to be, especially at higher speeds.... <br /><br /> Dunno if it's true, but that's the way it was explained to me... Personaly, I'll take three or more blades on my prop, thank you! Better balance, less vibration..

 

[mellowyellow]

Re: 2 blade props?

thanks Snapperbait, maybe I'll send it to a propshop<br />to be re-worked and try it some day. think a 3<br />blade it better overall prop though.

 

[JB]

Re: 2 blade props?

Two blade props make less drag and will reach higher speeds, MY, but they don't get good bite at lower speeds.<br /><br />On a high torque engine like the 1150 they are prone to cavitate and give a poor hole shot compared to a three blade.<br /><br />I agree with Snapperbait. Three blades is a much more "all around" prop.

 

[mellowyellow]

Re: 2 blade props?

would it change the rpms though?

 

[snapperbait]

Re: 2 blade props?

If both props are the same pitch and diameter, yes, RPM would likely increase with the two blade... As for how much increase, I would venture to guess 100-500 rpm, maybe..

 

[LubeDude]

Re: 2 blade props?

Everything sounds good to me!<br /><br />Many years ago I had access to all the props I wanted to try,(Had a freind that owned a marina)! I had a 15" trihull boat with an 85 Merc (non power trim) on it! I think I tried every prop he had for a mercury and the fastest prop turned out to be a 2 blade prop! If you are going to use power trim a cupped stainless (or aluminum for that matter) prop will always outperform the 2 blade props! I think thats why you never see them any more!<br /><br />I dont think I would spend the money to have it fixed unless you need a spare!!<br /><br />LubeDude

 

[mellowyellow]

Re: 2 blade props?

she has an SS 19p prop now and has got plenty of<br />bite to pull up 2 skiiers, but top end speed for<br />a day sounds like fun. maybe it was meant to<br />overcompansate for being underpowered by 20hp<br />(115 vs. 135...1050lbs hull weight, max hp 135)<br />it's either have the 2 blade re-worked, or the<br />"used to be new" other 3 blade AL. that has a<br />90' bend on one blade. <br />don't ask.... stupid human trick 4 sure

 

[LubeDude]

Re: 2 blade props?

Like I said, I do not think you will improve your top speed if you intend to trim out! Maybe, stranger things have happened with boats! Whats good for one isnt always good for another!!<br /><br />Give it a shot and let us know!! <br /><br />LubeDude