2018 Ranger Z518 prop confirmation

I am new to the game and this site is my haven for info I have been told. I have a new 2018 Z518 with a new Mercury 150 fours stroke. I have about 3-4 hours on it so far. Have had a few issues with speed and performance. I have followed the break in instructions from the start. This was propped incorrectly and currently running a 17 Tempest plus on it which is now going to be changed to the prop recommended from ranger being a 22 tempest plus. I am only getting about 48mph with the 17 and rpms seem to lock out at 4500rpm. Not sure if there is other issues but I don't get any warning chimes. The motor is set to the middle location of the mounting bracket. Should a prop change to the 22 possibly solve my issue? My plan is to get the new prop on and run it and if no better, is my step going to merc dealer to have it checked? Just wondering what others with the same boat are running to get the correct performance. Any input greatly helps. I know there are many variables but should this setup typically get mid to high 50's mph. I know rpm's range on site says 5000-5800.

I too have the same boat and outboard. My Mercury has a 22 tempest plus. I have ran as fast as 54 mph (with gear, two 250+ men, two power poles, and a half of a tank of gas). The rpms are in the mid 5000's. My question I would like to see is if anyone has taken out any of the exhaust gas rings on the prop to help with hole shot and if so how many?

Is your motor also mounted on the middle hole of the bracket? There are 5, mine is mounted on 3rd leaving 2 holes above and 2 holes below. I believe my pad to prop is approx. 4 inches on this height. I have leveled the pad and the motor. Could this be a little low and possibly raising it one hole help?

I am experiencing the same problem with my 2018, Z518 with a Mercury 150HP four stroke. I have the Tempest 22" pitch prop. I bought the boat March of ‘18 and was only getting 46MPH. I talked with Ranger, Berkeley Outdoors in Columbia and the nearest dealer which is 2.5 hours from my home in PA. They all say I should be getting 55MPH out of the boat so I took it to the dealer in WV and he said the motor was to high. Well he didn’t have the plate to lift the motor so I had to make two more 5 hour trips because I had to leave the boat. Well after I got it home and took it out, I still am only getting 48MPH with two guys and a half tank. I did go back out alone and hit 51MPH.

The motor was originally mounted in the fourth hole from the top but the Ranger Rep said it needs to be in the middle hole where it is now.

I was in touch with Mercury and after the engineer that I was talking with did some research, he said I need to put on a 8” Slide Master jack plate to get 55MPH.

The Z518 is a nice ride but I expected better performance.

You need a jack plate on any of them to get speed.