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#11
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I greatly appreciate the advice thus far. It sounds more and more I am going with a 19 mirage or it's like. On the motor though there is already a 4 bladed prop, I have not gotten the numbers off of it yet, but I really do not think the 4 blade is going to help.
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#12
03-21-2012, 12:19 AM
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Well, the number of blades on a prop is a compromise between vibration and efficiency. In theory, a one bladed prop would be the most efficient, but it would also create a lot of vibration. As blades are added, the vibration decreases, but so also does the efficiency because of the added resistance. Most props use 3 blades, because it's a practical trade off between efficiency and vibration. So if you're using a 4 blade prop on your engine already, then you'll get less vibration, so your engine will be smoother, but your efficiency will also decrease. Again, it all depends on what you want your engine to do in what kind of conditions. 4 blade props give you better hole shots due to more blades biting the water, but your top end will suffer because of the reduced efficency. 3 blade props will give you less of a hole shot, but you'll have a higher top end due to increased efficency. This is, of course, assuming that all other factors like prop material, rake and cupping are equal between the props.
Each of them plays a role, which is why it's possible to have two19 pitch props of the same diameter but one performs better than the other. This is where a knowledgeable marina prop shop comes in. They can advise you better than anyone else as to what is right for your boat. 
__________________
1987 V20 w/1987 150HP Yamaha on a Shoreland'r Trailer 1978 16.5 Airslot w/1996 120HP Force on a Four Winns trailer 1996 V21 w/1993 200HP Mercury on a Shoreline Trailer All towed by a 5.7L Hemi Durango. If God didn't have a purpose for us we wouldn't be here, so Live simply, Love generously, Care deeply, Speak kindly. (Leave the rest to God)  Silence, in the face of evil, is itself evil. Not to speak is to speak, not to act is to act. God will not hold us guiltless.
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#13
03-21-2012, 06:55 AM
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Quote:
What numbers are you getting from the existing prop...  ...if it is getting the max rpms your motor's specs allow, and not causing any difficulties, you may already have the right one...Post up some numbers rpms/speed @ increasing rpm range 2000, 2500, 3000, 3500, up to mfg's max rpm for us if you can...top down, light load, slick water, etc... If you haven't gone through this test w/existing, you may not need to change props... 
__________________
'74 V-20/ BF 150 '95 V-21/ BF 150 '84 V-20/ 200 2.4 Merc '87 V-20/'18 F150 Yamaha 
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#14
03-21-2012, 10:18 AM
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4 blade props do lose a little top end, much the same as a large diamter 3 bladed prop does. Modern 4 bladed props do alot better than old ones did. It all boils down to the boat and the application. I know my flats boat would only get to 52 with any 3 bladed prop I tried, but the 4 bladed TROPHY plus I put on it hit 61 and was still climbing when the wife smacked me and said enough(sold it before I had a chance to see just where it would top out). And most of teh time what you lose in top end with a 4 blade, you make up for with improved hole shot and mid range cruising.
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2011 SUNDANCE B20CCR SKIFF, 2011 YAMAHA 90HP 4 STROKE, 2011 KARAVAN SINGLE AXLE ALUMINUM TRAILER, LOWRANCE ELITE-7 HDI, MINN KOTA RIPTIDE TROLLING MOTOR 2000CC HYDRA-SPORT 225+HP EVINRUDE SOLD  AND THE PINK JEEP!!!! R.I.P. http://www.wellcraftv20.com/communit...ad.php?t=11664 
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#15
03-21-2012, 01:01 PM
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The last woman that smacked me...I introduced her to my best friend...she married HIM!!...lol!!...today their youngest son is ex-marine, secret service in the white house... 
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'74 V-20/ BF 150 '95 V-21/ BF 150 '84 V-20/ 200 2.4 Merc '87 V-20/'18 F150 Yamaha
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