Mercury pro xs 115 getting on plane issues

[Cserafin]

Hello I have been making tweaks to my setup and it’s not happy still. I have a 2021 pro xs 115 on a caymas cx18. When I used the boat in less humid weather with a 23p fury prop it ran like a dream. I have a hydraulic jackplate. I changed some things on the boat, added lithium’s, a seastar pro pedal and it got warmer now my hole shot is terrible, top speed took a 9mph hit and my rpms went from 6450 to 5400. I started to lose water pressure if the jackplate wasn’t anywhere besides all the way down which was always a problem but got worse but got worse over time when adding the lithium’s and the temp outside rising.


Most recently, I lowered the motor one hole to get it to not lose water pressure which now it doesn’t at all. I had two other people on the boat the other day and I couldn’t get on plane normally. I could only get on plane when the jackplate was all the way up and it took over a minute to get planing.

the prop seems big for the motor but was working ideally just a few months ago, I wouldn’t expect this crazy of performance differences this fast. Next I’m wondering if there is some sort of venting issue as I can’t get on plane without being all the way up on the jackplate. Any ideas and troubleshooting steps? I’m going to try a 21p prop if I can actually get my hands on one (sold out everywhere). Thanks for the help. Any more information I left out please ask and I will fill you in.

[EuropeanAM]

Chris- I see (at least) three posts related to performance and holeshot.

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Hello I have a merc 115 pro xs ct

When I first got my motor either the dealer or mercury didn’t connect the main power properly and was disconnected conveniently on the water where I was stranded. I trolling motored back to the ramp and loaded the boat successfully but since I was trimmed all the way down when it happened I managed to bend the skeg on my way back to the dealer (right from the ramp). The dealer claims it was Mercury’s fault but will repair the skeg by sending it out and getting it bent back into shape and re-powder coated.

First off, you could imagine I’m not too happy with the dealer about the whole situation. They did say they would repair it however. I do have a mechanic I trust to do the work who said around $1400 to replace the gear case completely and it would be right instead of a repair. What would others do? Replace the whole housing by someone reputable or go get it done for free in the method mentioned above? Largely I don’t know if a heating and bending it back is a good idea. I know there is no right answer and lots of personal preference here but would like to hear other people’s opinions

What was done to repair this? AND... has the propeller been replaced since this occurred?

Worked fine before the lithium’s. Yes hydraulic and yes it is all the way down. I need it to be all the way down on plane as well to keep water pressure

Nope prop was fine. Got it up to 51 now. Basically the issue was the motor needed to go lower so it was moved a hole down. Not enough bite. What was happening is I would lose water pressure and the merc would go into its failsafe mode and only give me 62% throttle capability. Not enough power to get out of the hole. Lithium’s just made the water pressure issue a bit worse given the motor wasn’t low enough and the jackplate couldn’t go any lower. Interesting issue

I can certainly see the weight difference changing your performance, but from the above statement, it sounds like you regained your lost performance. What changed?