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3 blade vs 4 blade pros and cons

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Fr8dog767

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I'm new to this forum and am building my bucket list boat. I have an aviation background and am familiar with the operational dynamics of 3 vs 4 blade setups on aircraft but not so much with a fan boat. My platform will be a 16x8 Diamondback powered by a Levitator LSX 454 engine. I'm thinking a 2:68 geared drive and an 84' Sensinich prop. I have heard some operators prefer a 3 blade setup as it will spin up faster. What are the benefits and drawbacks of 3 or 4 blades when considering the performance envelope. I plan to use the boat for fishing and gigging with a little dry running here and there. Thanks
 
What is the max rpm range of the Levitator and which Sensenich blades do you plan on using? a 4 blade JX would be my choice, at 5600 rpm with a 2.68 the prop speed will be just under 2100 rpm and 5400 would put it just above 2000. a 3 blade would probably work well also and save a few dollars but that is a big heavy boat, if you have the HP and gear to turn a big 4 blade which it sounds like you will the 4 blade should give the most thrust. A good friend has a 15x8 Alumitech with a 575 HP Mas 427 SBC/2.55 gear and 3 blade 82 inch JX, I haven't seen it run with a heavy load but it it is very impressive with an average load on water or dry ground. Darrin at Sensenich is great to deal with and will make sure you are happy. The best way to see which you prefer is test both setups in the same conditions back to back, it is well worth the time.
 
Swamp Thang is spot on. Call Darrin. I went thru the same thing just over a year ago. The team at DB was split on going with 4 or 5 JX blades for the boat they were building me. Darrin asked me some questions related to boat performance priorities, the custom engine I was having built and helped me decide on blades and gear box ratio. Darrin is great guy with lots of knowledge and more than happy to help answer questions. Let us know what you go with.
 
The Levitator 7.4 aka 454 is probably best with a 3 blade JX at that length. The 4 blade will work but with the "advertised" 525hp at 5,600rpm there is not a real need to add the extra blade.

I doubt you would be running much pitch with a 4 blade and you note your need is only for a "little dry running"

x3 Darrin with Sensenich is a great asset and he has a treasure trove of data to research
 
Most of the boats running the levitator/4 blade combo are your tour boats or work boats. You can expect more torque roll with the 4 blade. Whirlwind makes a damn good product for why you are trying to get as well. Patti or darrin will take care of you which every you choose.
 
65242342b905dd43171ee04afe0b0218.jpg

I just installed the 4 blade 88” jw ... switched from a 3 blade S. Curious to see the difference.
 
Pato Sicario said:
Swamp Thang is spot on. Call Darrin. I went thru the same thing just over a year ago. The team at DB was split on going with 4 or 5 JX blades for the boat they were building me. Darrin asked me some questions related to boat performance priorities, the custom engine I was having built and helped me decide on blades and gear box ratio. Darrin is great guy with lots of knowledge and more than happy to help answer questions. Let us know what you go with.
Click to expand...
What did you end up with and what is your engine setup? In the same predicament now!
 
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