Help! 2013 520c sudden loose rear end

[JustFishFor5]

Gonnabe

Yes sir, I’ll give you a shout in a couple weeks if I can’t get this square. Not gonna be on the water til the first weekend in March.

[JustFishFor5]

1BADAIR,

You may be right. I’m gonna test this theory in two weeks.

[JustFishFor5]

2500,

This sounds plausible. I’m gonna rearrange some equipment and run it in a couple weeks. Not gonna touch the poles until I test this theory. I’ll make sure I raise the atlas to make my PTP between 3 and 3.5

[JustFishFor5]

kingwood 250,

I think this is when I noticed it. I’m gonna test this theory soon.

[Redngoo]

This seems like what I have called "prop walk". The boat looses bite for a split second causing the back end to "dart" in a direction on the backend. Raise the motor a 1/4" at a time untill it goes away. I have experienced the same issue when moving in lower speeds.

[Bryan O]

I had a ‘93 482V that would do the same thing. Especially when I had a 24 Trophy on it. Mid speed, middle trim, and jackplate low. A prop expert told me that it was actually “walking” on the prop. Walking from blade to blade to blade, and the real only solution was trim up for more force down on the transom, or trim down for more bow bite. Seemed to make sense. It only happened on that 4 blade Trophy, and never on the Lazer that I ran. It was scary when it happened, but it was over so fast you didn’t have time to react.

[JACQUART21]

If you’re running at higher speeds with the motor trimmed all the way down, you are plowing the water with your keel. That’s would be further exaggerated with the jp all the way down. That is dangerous at speed cause any shift in side to side weight or other water conditions can cause the keel to bite hard one way or the other. Also, I could see this being exaggerated with less weight in the rear from the lithiums. Motor needs to be trimmed up once your on plane and running to get the keel out of the water.

[JustFishFor5]

***UPDATE***

After lots of theories and trial and error, ultimately the issue was the loss of weight when switching to lithium batteries, and not having the prop to center correct when using the hydraulic jack plate. Thank you all for all the assessments and ideas!

[mactlman]

***UPDATE***

After lots of theories and trial and error, ultimately the issue was the loss of weight when switching to lithium batteries, and not having the prop to center correct when using the hydraulic jack plate. Thank you all for all the assessments and ideas!

running too high? 7-8 seems to be fine on mine but with lifepo4 need to drop an 1" or so likely