14x19 to a 14x21 big difference?

JaCrispy

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I have a 22' cuddy 260/5.7 Alpha One with a 14x19 prop. I'm looking for a little more top speed, not sure how much a difference is between sizes. I can't give an accurate current speed, but I'm guessing it's right around 48-50. I got a GPS reading a while back at WOT at 43 but that was with 2 dead cylinders (long story). Anyway, engine rpm is 4600. I can overrev a little more but I throttle back to 45-4600 normally. Engine runs strong, gets on plane quick.
 

SkiDad

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i would think that a 21 would get you 2 more MPH - of course that is my thought if you keep the same brand of prop.
 

Barramundi NQ

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Can the motor rev harder but yiu hold it back at the throttle? Adding 2 inch to the pitch othe prop usually drops 500 rpm.
 

Barramundi NQ

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There is a propeller selector tool above your first post. Have you looked there?
 

JaCrispy

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Can the motor rev harder but yiu hold it back at the throttle? Adding 2 inch to the pitch othe prop usually drops 500 rpm.


Yes, I can overrev with the current setup. I throttle back to 45-4600 rpm. Anything I've looked up shows similar props for my configuration. Looks like going from a 19 to a 23 might be a big jump. I can't overrev 6-800 rpm.
 

Barramundi NQ

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Another option is to go to a for a stainless steel prop. They have less slippage and flex. So they are more efficient. They've got a thinner blade surface too. Does your local marine dealer have access to spare props for testing? When you get a new prop explain your complete setup and ask for their advice. Your boat will most likely take a 21 pitch and maybe a 23. Is it a 260 hp ?
 

JaCrispy

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The current prop is stainless. Yes, it's a 260hp 5.7 Merc. I'd love to test a 21 and 23, is that normal for repair shops to rent out props? I was assuming they had a 19p prop because it's basically a ski boat.
 
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jc55

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That 23 is probably not going to work. I went to a 23 from a stainless 19 just to try it on a 22 ish Baja 260hp/alpha1 and maxed out at 4100 rpms @53mph. Of course going 26mph @ 2600 was awesome. I'd try the 21p first.
 

JaCrispy

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That 23 is probably not going to work. I went to a 23 from a stainless 19 just to try it on a 22 ish Baja 260hp/alpha1 and maxed out at 4100 rpms @53mph. Of course going 26mph @ 2600 was awesome. I'd try the 21p first.

Cool, thanks for the info. Did you wind up with a 21 or back to the 19?
 

jc55

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I sold the boat a couple of months ago, but had every intention of getting the 21p for lowering rpms during light cruise. The 23 was just too much load on the engine.
 

JaCrispy

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You know what, last time out the boat kind of felt like it was dragging something. That's why I've been looking at a prop change. I was thinking last night, my drive has a doel fin on it, maybe I should remove that?
 

500dollar744ti

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Jul 23, 2012
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try the 21p, I don't think you're going to see much of an increase with top end, depends how much your boat weighs. I think you will get about 52 mph, I wouldn't try anything different until you can verify your current speed with a reliable GPS. If you don't have something to compare the new prop with it's a crap shoot.
 

dazk14

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Yes, try it without the fin. As stated, we need real WOT rpm's. No way a 23" pitch on that rig.

150-200 rpm change for each inch of pitch. Even more if you run much outside the peak power band.

You can always bring along a car GPS for speed.

What brand/model prop do you have?
 

JaCrispy

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Yes, I'm going to use my wifes car gps. I took it out once before and id gave good readings. The prop is a Michigan 033004-1. Stainless 14x19 3 blade.
 

HT32BSX115

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Any GPS (iPhone, Droid etc) is good for checking your speed (unless you're on a fast moving river..... then you have to do 2 runs in opposite directions!)

Just as important is the need for a KNOWN tach! defective tachometers can be off as much as 500 RPM at the top of the range!

If you're using an inaccurate tach, you're wasting your time trying different props.
 

jestor68

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Jun 12, 2012
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Since the Mercury prop selector says a 17/18 pitch should do about 4600 rpm with your boat, it appears that we may be dealing with another whacky tachy situation.

I'd get that tach verified before running off to buy more props.
 

JaCrispy

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With the 19p and the doel fin still installed I got 4900rpm @ 43/44mph (gps). I was hoping for a little better mph than that. I'll try removing the doel fin next time out and see where I'm at.
 
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