Anyone have any ideas?

Today I was out on my 2016 t23 and all of a sudden felt a shudder. I stopped cause I figured I had brushed a stick or caught a rope etc. after inspecting I see nothing out of place or wrong under the boat. Prop and shaft look to be fine but any time I go over 5 mph I can hear a slight squeal and awful vibration. The faster I go the worse it gets. There is one small nick in the prop about 1/4 in MAX, I doubt that would cause all this ruckus?

Did you feel any kind of strike? Usually, vibration is caused by prop issue. May not be the case here but on newer boat like this, that would be the first place I looked. Have you been able to determine where the noise is coming from? The squeal makes me think there could be something else going on and maybe something struck your shaft and then hit your prop causing that ding....just thinking out loud here.
Hope it ends up being an easy fix for you. Nettle Props out of Austin TX is where I sent mine for repair...they do a good job and have a lot of experience.

Do those boats have the regular old style rope seal around the prop shaft ? Could that be dry causing a squeal ?

If you hit something hard enough to put a 1/4 inch "nick" in your prop, that is where I would start. That ear of your prop could be bent and you may not even be able to see it. It takes next to nothing to cause a vibration that you can feel in the steering wheel and floor.

guarantee its your prop. don't run it like that either, will mess up engine and vdrive. get it fixed. take this opportunity to buy a back up prop if you don't have one along with the tools to change it.

Agree. I barely bent the very tip of a prop a few summers back. Like a 1/16th of an inch on one tip curled over and there was a noticeable vibration. I know the NIBRAL is designed to protect the drive train, but it takes next to nothing to damage one. That wouldn't cause a aqua or squeal, but it would the vibration.