I need a new prop for my boat, it has a aluminium 14 1/4 by 21 pitch. I would like to put a stainless on, but in the stainless should I go to a 23 pitch or stay with the 21 pitch. Right know I have a good hole shot & good top end with the 21. How will the 23 change that? Any suggestions would be great. 
What rpm do you run at WOT with a typical load?
Your dealer should have some demo props for you to try. If not. Go with the 21.
If you can, try out a 19p 4-blade. It will give that boat a lot of bow lift.
-J.
I just went thru this.
I was told to stay with the 21.
I have always had a great hole shot and top end was good in my books.
Next week we go look for the rock that caused this damage.
I may have a new smallie spot 
Red 3
Try this site,
http://www.turningpointpropellers.com/default.php
Hello
If you have a 21p yam prop and go to like a 23p lazer merc or turning point prop it might be a bit much because the yam props do not have a lot of bite where the tp laser have more bite if you have a couple 100 rpm to spare try a turning point in 21p I think you will be happy
later
Kevin
Your boat does run really good, don’t remember the exact rpm’s you were running, but I think a stainless in the 21 range isn’t going to be too far off, but like suggested find a dealer that will let you test them out. Long ago I think someone suggested Marine specialties in Redwing, never looked into it yet, apparently my wife doesn’t buy my excuses for a new prop quite yet. 
What rpms are you running at wot loaded and light?
Around 5000, the max is 5600 but I’ve never maxed it out. Now needing a new prop after hitting that submerged log on pool 3, I thought I’d upgrade to a stainless.
one other thing to remember is if you chose to go to a stainless from a alum and hit that same log it might cost you more than a new prop, Just a thought… stainless is nice but sometimes it is to strong…
later kevin
I have never know anyone that has wrecked a lower unit from having a SS prop. I think it’s more or a wive’s tale. Perhaps it happens on a very rare occasion, but most times I think the SS prop will win.
Mark, here is a good read that I used when selecting props earlier this year for my rude 150.
One thing, since your wot max rpm is 5600 and your running at 5000, I would try a 19 to see if you can pick up a couple hundred revs and gain a little on the top.
If you go to the 23, you would be running around 4800 revs at wot, your hole shot would improve, but you top end would suffer.
Jami
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If you go to the 23, you would be running around 4800 revs at wot, your hole shot would improve, but you top end would suffer.
I think you got that backwards. Holeshot will suffer if he goes from a 21P to a 23P.
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If you go to the 23, you would be running around 4800 revs at wot, your hole shot would improve, but you top end would suffer.
I think you got that backwards. Holeshot will suffer if he goes from a 21P to a 23P.
I agree. Plus increasing pitch is no guarantee you will pick up speed if it’s too much prop for the motor. Otherwise everyone would run 30p props!
Go with the 21p and the first time you run it open up that baby! Try to hit the rev limiter or 6000 rpm’s whichever comes first. If you hit 6000 and feel there is a lot more motor left, try a 23.
-J.
People say run them 6K all day long, though the owners manual seems to indicate running in the 4500-5500 range (I’ll be thats what it says), people who seem to know what they are talking about that I’ve talked with say 5500-6000 is more the range you should be shooting for.
I like Jon’s ideas 
Mark,
If you have time call Supreme Marine in Mpls they have the Merc demo prop system, 25.00 deposit and they will let you try a couple of diiferent props, I would not go any more then a 21p, you may end up with a 19p in SS, SS props typical have a larger blade surface and more cupping which gives more bite and are more efficient, you more than likely will gain rpm, speed and holeshot, a 19 or 21 Tempest would be a good choice.
I assume you have a 2 stroke, 18fisher tried a 21 and it was to much for his 1800 Fisherman with a F150 Yamy I think he ended up with a 19 Tempest, you dont want a small blade prop like a Laser 2.
Go to mercs web site and do some reading
What speed and rpms and what is your holeshot like now?
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Quote:
If you go to the 23, you would be running around 4800 revs at wot, your hole shot would improve, but you top end would suffer.
I think you got that backwards. Holeshot will suffer if he goes from a 21P to a 23P.
Yup, got it backwards…
http://www.boatramp.com/prop_applet/PropAnalyzerAppletG.html
Try this, plug in some numbers that you know
Kurt with the 21 alum. I’ve got a great hole shot & a top end of 50 mph at 5000 rpm. So hopefully the ss prop can improve that.
Go to that site and plug in some numbers, I found it helpful, remember to add a 1″ to the pitch for SS since it cupped.
I really think a 19 Tempest would be the ticket, when I ran 19 aluminum it would over rev a bit, I went to a SS 19 Pro Series on my My Pike with a F115 and found the rpms perfect 5700 vs 6100 rpm’s
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