3 blade prop vs. 5 blade prop

[dksask]

I have a 2001 115 hp evinrude. It is on a 16'Larson Flyer and use it mostly for skiing. It pulls an adult skier out of the hole pretty good, but can only get about 45 MPH at WOT( the dealer told me it should get around 55MPH). It has a 3 blade 14" 17 pitch aluminum prop on it. I recently saw a boat with a 5 blade stainles steel prop on it. I was wondering what the difference would be if I was to put a 5 blade prop on and if it would get me anymore speed and/or thrust to pull. Any comments/suggestions on what to do.

 

[JB]

Re: 3 blade prop vs. 5 blade prop

Howdy,Don. You need to know/we need to discuss rpm at WOT. It is unlikely that a 4 or 5 blade prop would do you any good (except to excite people at the ramp).<br /><br />In general, three blade props are the most efficient in outboard diameters. Four and five blade props are compromises to allow for the diameters that outboards can carry.<br /><br />There is plenty of room to improve your prop without going to the inefficiency of more blades.<br /><br />Red sky at night. . .<br />JB

 

[JasonJ]

Re: 3 blade prop vs. 5 blade prop

Is that 45 towing a skier, 45 with just you in the boat, or 45 with several people in the boat? I would say you are doing alright getting 45 out of a 115 horse motor. More blades will not increase your top end speed, it will only increase your holeshot. Those props are usually on boats with serious power, so much power that they need the extra bite. The more blades you have, the more drag you have, and without the high torque to make up for it, you will lose speed. Do you have a tach? If so, just shoot for getting your rpms into the range they should be at WOT with a good three blade prop, and you will be happier. Good luck...

 

[Jacques321]

Re: 3 blade prop vs. 5 blade prop

Personally I think your dealer lied to you about that top end speed you should hitting with a 115. 45MPH sounds just about right. Now if you go to a Stainless 4 blade prop youl definately get a better hole shot, but you won't go faster, in fact you may drop a couple of MPH. The five blade props are geared towards 6 cylinder outboards.<br /><br />If you're serious about getting a SS prop contact your local dealer and experiment with 3-4 props(both 3 & 4 blade) one that will give you that added hole shot for skiing, and perhaps a few more MPH's at the maximum RPM range. Take your time and pick the right one... they're expensive, but are worth the expenditure. Who know's maybe you'll want a 3 blade for cruising and a 4 blade for skiing.<br /><br />Once you own a SS prop you won't go back to aluminum believe me. They don't just look good on your outboard they perform/handle better and last longer than aluminum props.

 

[eriklepe]

Re: 3 blade prop vs. 5 blade prop

A prop seller/maker here in Norway once told me that 4 and 5 blade props is only useful on larger and heavier boats. I have a small and light boat like you, and a 4/5 blade prop will only be good for greater accleration ( so it will be great to pull skiers), but you will loose 5-10 knots on the top speed. The best propeller for your boat is a OMC Raker SS prop 13 1/4' pitch 20-22 ( maybe less). This will increase your speed with a couple of knots when engine is tilt/trim is right. It sure did to mine... If the angine is new it should have about 5800 RPM, the older ones should have 5400.

 

[rlouns]

Re: 3 blade prop vs. 5 blade prop

From what I have read a one blade prop is the most fuel effecient and the most vibrating. Two blades less vibration less fuel economy. Three blades - the best trade off between fuel economy/vibration.<br /><br />Just my 2 cents.

 

[Dhadley]

Re: 3 blade prop vs. 5 blade prop

Here's a few "rule of thumb" things about props. A stainless runs at a higher X dimension than an aluminum. A 4 blade runs higher than a 3 blade. When the 4 blades first became popular you could gain a lot on bottom end and sacrifice a little on top. With todays technology and the correct set up you can usually improve your holeshot and gain top end. However, if you have the optimum set up for a 3 blade and simply try a 4 blade at the same X dimension I suspect you will be disappointed. Most of the time you will be able to raise the motor high enough with a 4 blade that a jackplate is required to take full advantage of the technology. In some cases we have been able to run 20" motors on 25" transom with the 4 blade props.<br /><br />I know this has been very general and quick. <br /><br />Good luck!