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Old 03-03-2011, 08:29 PM
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Default 4 Blade vs 3 Blade Propeller

If I change from a 3 Blade to 4 Blade propeller would my fuel milage get better are stay the same? The motor would be pushing the boat easyer at a lower RPM right. I'm running a 1997 130 HP Johnson 20 ft angler.
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Old 03-03-2011, 10:05 PM
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Not sure, but I believe you should be able to stay on plane at a lower RPM ... should increase fuel economy. Word on the street says your top may come down but your hole shot should improve (better lift).
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Old 03-03-2011, 10:27 PM
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Call a prop guy and buy from him. You will get great advice and it wont add that much to your cost if at all. W
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Old 03-04-2011, 06:09 AM
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A four blade prop will pull better at low speeds and get you up on a plane quicker, but it will have more drag and be marginally less efficient at higher speeds. At cruising speed, chances are your economy would be a little poorer, but much depends on the boat, the weight, and the cruise speed.
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Old 03-04-2011, 07:14 AM
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Every additional blade on a prop slows you down.
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Old 03-04-2011, 08:42 AM
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I am a four blade fan.
I believe your fuel economy should be marginally better for the following two reasons--more efficient less cavitation and less wasted energy and plane at a lower speed in rough water eliminating running at that inefficient less than planing speed.
You will get better handling around the dock and yes, lower top speed.
Make sure your engine will reach desired rpms at wot. A four blade prop of the same pitch will run at less rpms than the three blade because of the greater efficiency.
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Old 03-04-2011, 08:56 AM
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If you do a lot of low speed trolling, you may notice that the four blade prop will cause your SOG to increase at the same RPM.
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Old 03-04-2011, 09:32 AM
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Quote:
Originally Posted by Jack Hart View Post
A four blade prop will pull better at low speeds and get you up on a plane quicker, but it will have more drag and be marginally less efficient at higher speeds. At cruising speed, chances are your economy would be a little poorer, but much depends on the boat, the weight, and the cruise speed.
What he said.

A lot depends on your boat and motor set up. One thing is for sure, a 4 blade prop will give you a better hole shot however it will have less top end. More than likely your fuel economy will be slightly less at higher speeds and at WOT and slightly better at lower speeds only because you can get on plain at a lower RPM. Either way, your fuel economy differences will probably be very minimal.

As stated above, talk with a prop expert as "pitch" and "cup" play a big part in your top end, hole shot, and the overall way your boat rides.
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Old 03-04-2011, 09:40 AM
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All depends on your current performance, how you load the boat, the speeds you want to run etc....

With your normall load......
What prop do you currently run.
What rpm/speed do you get at cruise and wide open.
What speed do you want to cruise.
Is there anything, such as ventilation in rough seas, porpoising, bow steering, minimum planing speed, top speed, acceleration, or anything that you would like to improve on or fix?
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Old 03-04-2011, 10:02 AM
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Does anybody run 4 blade on their skiffs ? I have a 22' Sundance ( similar to a Carolina Skiff ) & was considering a 4 blade prop ? Thx. for any help ...
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Old 03-04-2011, 10:33 AM
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Yamaha's site has tests of a 31' Contender with 3-bladed 21" prop and 4 bladed 22" prop. Looking at the date, I'm guessing it was the same boat on the same day.

MPG at 3500RPM was almost identical, but the 3 bladed prop was 3mph faster. MPG was with ~.1 MPG through the whole RPM range, and top speed w/ the 3-bladed prop was ~1mph greater. With this engine on this boat, it looks like the 3-blade has a slight edge, but like others have said, it depends alot on the boat.

In talking to a Yamaha tech about a repower, he said he likes the 4-blade for the extra bite in turns and out of the hole, but would test both on my boat before making the final call.
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Old 03-04-2011, 11:06 AM
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I had two different boats 31 Jupiter with F250 and a Ranger 2400 with an F250 that both had improved mileage and speed at cruise RPM's switching from 3 - 4 blades. In both scenarios I went from a Yamaha 23 pitch to Merc Rev 4 21P. I beleive a lot of my success was due to Mercury making a much better Propeller then Yamaha and in both scenarios the boat ran better with the bow lift created from the REV 4. I recently bought a 3 blade 23p Tempest Plus to try on my Ranger. I am very excited to see the results.
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