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First a disclaimer. There's a BUNCH of people who know more about props than I do.

Mercury has a prop selector on their web site that I think is pretty good.
What prop is on it now? What do you want it to do differently?

I slightly damaged my original prop. It still worked fine but I wanted a spare. I got a stainless steel prop from Prop MD, and kept my original one for a spare. I kept the same size and pitch, but in stainless. Holeshot is a little slower but it's faster overall. I normally cruise at 4500 rpm. The new prop is 3 mph faster at 4500 rpm. At full throttle it's 2 mph faster and 200 rpm lower than the original. My prop would porpoise when trimmed up. This one doesn't.

I contacted Prop MD, told them what I wanted, and got the prop they recommend.

FWIW, Tracker Classic XL, 50 horse Merc. Top speed, normal weather with the old prop trimmed up, porpoising was 35.5. New prop is 37. Cruise at 4500 old prop, 26, new prop 29.

Last winter when it was 22 degrees I got 38.9 mph with the original prop. I expect to go 40 in those conditions this winter. I don't care about speed. If I did I would have bought a faster boat. It's just something I have to know. I rarely go over 4500 rpm.
 
I fully understand about props, I am anal about props! Does your new prop have vents? On my older boat I ran a 22 pitch prop and finally ran all three plugs in, drilled out to 1/2 inch to keep the prop balanced.
 
A Z7 with a 175 should be able to turn a 25p or maybe even a 26p prop with ease. I say this because I have a friend who had a Z7 and a 150 that ran a 24P Tempest with god results----BUT what prop is best for you?? This is harder to determined based on many factors. What is best or better cannot simply be based on what someone else ran even with the exact setup. It may be close but never the same. Every boat is different based on one key factor--loading! Weight plays a pivotal role in every boat setup and not just the amount of weight but how it is distributed around the boat (300lbs of stuff in the back is not the same as 300lbs in the front). Lead acid batteries vs lithiums etc... Propping a boat comes down to expensive trial and error. Some folks may have friends with a few props they can borrow and try, some don't. Google and Youtube are great places to obtain information on "How To" but again it will come down to trial and error. I could tell you all day that a 25P Fury 3 or Fury 4 will work great but depending on a bunch of different things they may not work at all!! The perfect prop is one that has great holeshot, runs up to or near the rev limiter with a low slip percentage (meaning the best top speed), and handles great in rough water conditions.
 
For a two stroke outboard engine 24 or 25 pitch prop will work but I have a 4 stroke outboard engine, what I can figure out that a 22 pitch prop should work. I am running a 21 pitch prop and top rpm's is 5200 and about 55 miles hours
 
For a two stroke outboard engine 24 or 25 pitch prop will work but I have a 4 stroke outboard engine, what I can figure out that a 22 pitch prop should work. I am running a 21 pitch prop and top rpm's is 5200 and about 55 miles hours
Bobby, 1st let me say that based on the numbers you just gave that your setup is all wrong, you have a rigging problem or a problem in the motor itself. You should be running at least 5800 rpms at WOT. 5200 RPMs with a 21P prop on a 175 4 stroke on that hull tells me something is wrong. You may have the motor buried on the transom. Your not getting WOT which is a common rigging problem with 4 strokes (check the high and low stops if you have a hotfoot). Could be an actual problem with the motor. I have personally never owned a 150/175 4 stroke BUT from my experiences with the new larger 4 strokes is they have at or near the same rev limiter and LOTS more torque due to higher displacement. Having much more torque allows you to turn a larger wheel--not the opposite. If you can only get 5200 RPMS out of a 21p prop what makes you think a 22p prop would be better?? Another thing people don't realize is not all props have the same diameter. Props for bass boats will typically vary from 13 3/4 to 15 1/2 inches +-. This will allow a higher pitch with a lower diameter prop and visa versa with a larger diameter prop.
 
I have a 6 inch jack plate, atlas hydraulic one. The motor is mounted in the top holes to the jack plate and the jack plate is mounted bottom holes to the boat. And I have power poles too. I do think the setup is wrong. Looking at it wondering if the motor setting up to high. It's look like the original mounting of the motor sits lower, if the jack plate was not there
 
Bobby, 1st let me say that based on the numbers you just gave that your setup is all wrong, you have a rigging problem or a problem in the motor itself. You should be running at least 5800 rpms at WOT. 5200 RPMs with a 21P prop on a 175 4 stroke on that hull tells me something is wrong. You may have the motor buried on the transom. Your not getting WOT which is a common rigging problem with 4 strokes (check the high and low stops if you have a hotfoot). Could be an actual problem with the motor. I have personally never owned a 150/175 4 stroke BUT from my experiences with the new larger 4 strokes is they have at or near the same rev limiter and LOTS more torque due to higher displacement. Having much more torque allows you to turn a larger wheel--not the opposite. If you can only get 5200 RPMS out of a 21p prop what makes you think a 22p prop would be better?? Another thing people don't realize is not all props have the same diameter. Props for bass boats will typically vary from 13 3/4 to 15 1/2 inches +-. This will allow a higher pitch with a lower diameter prop and visa versa with a larger diameter prop.
Update lower the jack plate down one hole and I can get 5500 rpm's, got to work on figuring out the rest of setup
 
Bobby, everything has pretty much been covered by all on this topic. A very good you tube video is available on weight distribution. I am running a larger hp engine on my Z20, I have the ProXS 225 on my boat. As hole shot was mentioned I will mention mine. I have distributed the weight accordingly and with great results. My hole shot is explosive, I have a 23P Fury, my boat darn near comes out of the hole on a plane, the holes on my prop are wide open, no plugs. Also mentioned was the jack plate. I have an Atlas 10" hydraulic jack plate. After getting together with Dan White and Johnnie Morse at the Harris Chain Bass Masters this past season, they thought my setup was right on. With the jack plate set at 2 1/2" I get the best performance, this includes hole shot, as well as top end. My boat was initially setup by my marine outlet after coming off the truck, they said it was the fastest Nitro they had ever seen. On their test run they state they had it up to 78 mph, I have had it to 74, my question at that point was were you running the GPS of speedometer?? On my boat there is typically a 3 mph difference between the two, the speedometer was the 3 mph higher. I don't imagine your having chine walk issues with your boat but my starts at 68 mph and is tricky driving thru it. Glassy water conditions make it harder, a slight ripple really lets this beast go. Backing up a bit, there are factors, weight distribution is where you probably need to start. Hole shot and slippage is where I went from there. From there I went to handling at upper end. I tinkered with the jack plate, slightly raising and lowering before I found the sweet spot. I now have it dialed in and operate under consistent conditions. Bobby, for my setup the 23P Fury came with my engine and after experiencing the immediate explosive hole shot I saw no reason to fix something that wasn't broke. Hope this may help you..
 

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