2 blade vs 3 blade prop

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Fastcatak
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2 blade vs 3 blade prop

Postby Fastcatak » Sun May 13, 2012 6:03 pm

Hey everybody, this question is not trying to compare prop makers. What I'm trying to decide is whether to use a 2 blade 74" or 3 blade 72" for my 520 recently converted from a 470. I know there are a lot of threads comparing wt, q, ngh, h, r, etc. I'm trying to figure out if the 2 or 3 is going to have better low end push, run dry, top speed etc. on a 17'x7' boat carrying heavy loads with 3/8" UHMW.
So for each brand of prop, using their recommended sizes and styles, how would a 2 and 3 compare?
Thanks

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CONTINENTAL CRACKER
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Re: 2 blade vs 3 blade prop

Postby CONTINENTAL CRACKER » Sun May 13, 2012 6:38 pm

The 2 blade q has better low end and the 3 blade h has better top end. I likes the way my 3 blade h jumps out f the hole better than the 2 blade q and the 3 blade h also has way better top end. I have run all different props and I have like the 3 blade h better than them all so I have stuck with the 3 blade h. Now when I have the extra money I want to buy a set of ngh blades to put them in my 3 blade hub.I would like to try the ngh blades before I buy them. The 3 blade h in my opinion the 3 blade h is a real responsive prop, plus it had great top end and doesn't run out of push like other props I has run. I have run this 3 blade on a 220,470 carb and injection and now I have it on a 520 injected, but I did also have it on when my motor had a carb on it. But I didn't like the carb as much as I liked the fuel. Injection so I put my fuel injection system on my 520 and sold the carb. I have run a couple different props on my 520 and I ended up staying with the 3 blade h.
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atvracer16
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Re: 2 blade vs 3 blade prop

Postby atvracer16 » Mon May 14, 2012 10:13 am

So you're saying a 2 blade would be better if I wanted more low end?
13' Aluminum w/ SBC 350 (440hp), 2.38 Stinger Soft Drive, & 2 Blade 76" R Series

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plumcrazy
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Re: 2 blade vs 3 blade prop

Postby plumcrazy » Mon May 14, 2012 10:17 am

a 2 blade is more efficient in a wide blade and a third less money 8)

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jimmyflfr
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Re: 2 blade vs 3 blade prop

Postby jimmyflfr » Mon May 14, 2012 11:26 am

My caddy dd boat hauls loads of people. The 3 blade h flat out out preformed any 2 blade I've tried from push to top end. My boat won't run dry with any. Lol but it will haul, get on plane and more top end better with the 72" h. That's my experience.


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Re: 2 blade vs 3 blade prop

Postby DAGWOOD0520 » Mon May 14, 2012 3:53 pm

Just as important as the number of blades is prop diameter, how big of a prop can you get in your cage and still have 2" of clearance around the prop?

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Fastcatak
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Re: 2 blade vs 3 blade prop

Postby Fastcatak » Mon May 14, 2012 8:16 pm

74" would be max for my set up.

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JAMES
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Re: 2 blade vs 3 blade prop

Postby JAMES » Mon May 14, 2012 8:29 pm

JUST BECAUSE U HAVE A 3 BLD DOESENT MEAN IT WILL OUT PERFORM THE 2 BLD IVE HAD 2 AND 3 BLD PROPS IT ALL IN WHAT U WANT IT TO DO AND WHAT U CAN TURN PEOPLE PREACH ABOUT THE H I LIKED IT BUT I WOULDENT GIVE 100.00 FOR A NEW ONE THEY ARE LOUD AS HELL AND DEAD ON THE LOW END IF U ASK ME .. THEY ARE A TOPEND PROP ... + JMO THEY ARE THE FLATTEST BLDS OUT THEIR ANY WEAK MOTOR CAN TURN EM ..FROM WHAT IVE TRYED THE2-BLD Q IS THE BEST FOR PUSH THE 3-H BEST FOR TOPEND AND THE WIDE WHISPER TIP 2 BLD HAD EM BEAT ALL AROUND ... IF U WANNA GO FAST GET A WARP DRIVE .. PUSH Q- WT JMO THEIRS ALOT OF TALK ON THE FUNNY LOOKIN PROP THAT NGH :lol: GOOD TALK THOUGH
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Re: 2 blade vs 3 blade prop

Postby WhirlWind Propellers » Mon May 14, 2012 8:38 pm

Fastcatak wrote:Hey everybody, this question is not trying to compare prop makers. What I'm trying to decide is whether to use a 2 blade 74" or 3 blade 72" for my 520 recently converted from a 470. I know there are a lot of threads comparing wt, q, ngh, h, r, etc. I'm trying to figure out if the 2 or 3 is going to have better low end push, run dry, top speed etc. on a 17'x7' boat carrying heavy loads with 3/8" UHMW.
So for each brand of prop, using their recommended sizes and styles, how would a 2 and 3 compare?
Thanks



This is a good question. Generally speaking, it is more efficient to move a larger column of air slower that to move a smaller column of air fast. There are less viscous losses and lower form drag with slowing air velocity. What this means to you is that the larger diameter 2-blade should deliver more thrust, all other things being equal. The smaller diameter 3 blade can be quieter because the blade tip speeds are slower.

When comparing a 2 blade to a 3 blade, it should be the same blade style and size (width, diameter, etc) otherwise you would be comparing apples to oranges. Ultimately, it boils down to getting the propeller that will have the optimum blade angle for your engine's power. The hp and operating RPM of your engine will dictate the propeller sizing options, including diameter, blade width, and number of blades for best performance. Other factors to consider are cage clearance, price, aesthetics, response and handling (i.e. personal preference).

A 520 that is putting out 285+ hp, could chose between the 2-blade 74" Whisper Tip standard and the 3-blade 72" Whisper Tip Narrow. Either propeller would be a great match for optimum performance.

Best to you.

Sincerely,
-Patti
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Re: 2 blade vs 3 blade prop

Postby SDeatherage » Mon May 14, 2012 8:40 pm

I had a three blade 74 inch H and now I have a 72 ngh it performs similar but the ngh has more down low push but still the same top end push. But the ngh is much quiter. My boat jumps on a plane with the ngh.
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Fastcatak
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Re: 2 blade vs 3 blade prop

Postby Fastcatak » Mon May 14, 2012 9:57 pm

Thanks for all the input. It seems that most are saying a 2 blade 74" would have more "low end push".
If that means to get moving with a heavy loaded boat or possibly off of a gravel bar then that's what I'm after. Not so much after the top speed.
Patti, Im not trying to compare apples to oranges. Just trying to determine how the two props you recommend would perform differently.
"A 520 that is putting out 285+ hp, could chose between the 2-blade 74" Whisper Tip standard and the 3-blade 72" Whisper Tip Narrow. Either propeller would be a great match for optimum performance. "

If they are so close that the performance difference is not noticeable by seat of the pants then I guess the price difference would be the deciding factor for me.

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Re: 2 blade vs 3 blade prop

Postby CONTINENTAL CRACKER » Tue May 22, 2012 9:39 pm

JAMES wrote:JUST BECAUSE U HAVE A 3 BLD DOESENT MEAN IT WILL OUT PERFORM THE 2 BLD IVE HAD 2 AND 3 BLD PROPS IT ALL IN WHAT U WANT IT TO DO AND WHAT U CAN TURN PEOPLE PREACH ABOUT THE H I LIKED IT BUT I WOULDENT GIVE 100.00 FOR A NEW ONE THEY ARE LOUD AS HELL AND DEAD ON THE LOW END IF U ASK ME .. THEY ARE A TOPEND PROP ... + JMO THEY ARE THE FLATTEST BLDS OUT THEIR ANY WEAK MOTOR CAN TURN EM ..FROM WHAT IVE TRYED THE2-BLD Q IS THE BEST FOR PUSH THE 3-H BEST FOR TOPEND AND THE WIDE WHISPER TIP 2 BLD HAD EM BEAT ALL AROUND ... IF U WANNA GO FAST GET A WARP DRIVE .. PUSH Q- WT JMO THEIRS ALOT OF TALK ON THE FUNNY LOOKIN PROP THAT NGH :lol: GOOD TALK THOUGH

I have run the q and the wisper tip. I couldn't wait to get my 3 blade h back.I don't know why your motor wouldn't turn your 3 blade, all 3 of my motors I have had my 3 blade h on had no problems with snap or low end with the prop. I am also calling like I have seen it, I have let many people try my 3 blade h and all of them went out and bought one. When they were running my prop I was running there 2 blades and warp drives.I personaly like the 3 blade h. It is the best all around prop.I like the top end out of it for the low rpm crusie on the water and also like the top end for running on the hill where I spend most of the time I am up the river.I will be trying out the ngh blade in my hub. But I wouldn't ever go back to a 2 blade prop. I like how with the 3 blade on the hill loaded down all I have to do is feather the throttle and it goes. With the 2 blades in the same situations I had to stay in the gas. That is a no brainer. But everyone doesn't run with 3 adults 4dog and a couple hogs and run the hill like we do. Its not just me who thinks the same about the 3 blade h. The man who bought my old laser boat ended up getting ride of the 2 blade for the 3 bladeh
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Re: 2 blade vs 3 blade prop

Postby scottymartin » Wed May 23, 2012 7:08 am

Good question for all you Boys... I have a fresh O380-190hp, on a 12' Scorpion, with a 68"Q. Trust me I'm Free. I love the low end push, don't need top end. Would a 3 blade, help me, any more at low end ??
Little Bear 12' Scorpion w / O-360 200hp

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Re: 2 blade vs 3 blade prop

Postby air-roberts » Wed May 23, 2012 7:28 am

like patti said depending on the h.p. and blade type your gonna want 1. length 2. pitch so depending on your h.p.rating and getting the blade some pitch probably the 2 bld because it will let you get extra length and pitch more so than the 3 bld
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Re: 2 blade vs 3 blade prop

Postby swampjunkie » Wed May 23, 2012 8:42 am

Fastcatak, How many hunters do you have on the boat with that Moose on the bow? That's a lot
of meat to pack back to the river. Do you do guided trips? If I was buying the a prop I would talk
to the manufacture of your choice and have them send you a 2 blade hub and a 3 blade hub and then
3 blades in 72 and 3 blades in 74. Try the combos of 72 2blade vs 74 2blade, which ever one you like best . Then try a 72 3blade vs a 74 3blade. Then put the best 2 blade against the best 3 blade and see what you think works best.
Only then will you know what works best on your application. Then send back what you did not prefer.
If you ended up liking a 2 blade set up then I would keep 1 extra blade as a spare incase you damage 1 you will be
able to be back running in no time since all of the blades are matching sets. I know it is a extra up front cost but you will get refunded when you ship one of the hubs an blades back within 30 days . So the real extra cost ends up being the shipping back price of the undesired blades and hub. JMO

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Fastcatak
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Re: 2 blade vs 3 blade prop

Postby Fastcatak » Thu May 24, 2012 7:53 pm

There's two of us, most of camp, and a moose being hauled out.
That animal was taken on the river so we were fortunate to get the boat within 50'.
Not guiding just trying to put meat in the freezer.

Btw we chose to go with the 74" 2-blade whisper tip. Excited to try it hopefully
In the next couple weeks. Thanks for all the input.

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Re: 2 blade vs 3 blade prop

Postby CONTINENTAL CRACKER » Thu May 24, 2012 8:04 pm

190 hp I don't think I would have gone with a 74" prop try a 72" 3 blade h. I have seen on here people say a 220 gpu is nt 220 hp. But motor builder say they r 220hp who knows. I know I had a 3 blade h on my stock 220 on a big heavy boat and it woke up big time. It would go anywhere after igot the 3 blade h loaded down and good low end and great top end. I like the top end more than I wanted low end for crusie rpm and for running the hill.jmo
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