HIt something - What to check

Inspect the prop carefully. Look for exact same contours on each blade, if one has a bend or is shaped differently you found the vibration.
If you dont see any shape difference place two fingers on the prop, one inside and one outside and slide them up and down the prop leading and trailing edges. Sometimes you can feel bends that you can't see.
With the prop off you can take a magnetic mount dial indicator and check to see if the prop shaft is still straight at the prop mount location. As close as possible to the prop nut location would be best.
Eyeball the alignment of your strut to see if it is still square on the hull.
A 3 mph hit can certainly do damage but I would think it will be minor.
Any bend of even one prop blade can give you trouble.

KENO wrote: I can never seem to find anything magnetic under there,

That's why I have one of these:

Definitely the prop. Appreciate the info fellas.

I guess I am lucky, my trailer has a prop guard that runs directly under the prop shaft.
It is easy to mount the magnetic mount for the dial indicator on the prop guard to measure my prop shaft.   I realize some trailers do not offer this advantage. Good ideas on the work arounds you guys have come up with.

So i did get a new prop and all the vibrations are gone. Very smooth as it should be. My question is should I still check the shaft? I don't have the dial indicator and would have to purchase one. (I know they are fairly cheap) Not against it if you guys think I still need to check it. Thanks for all the info.

Gary

Thanks!

Probably not. Can you explain what "lapping" a prop in means?

Gary

Also I did do a very rudimentary test on the shaft. Took a level and held it about 1/16th from shaft while someone turned prop. Visually looked okay. I know this is far from scientific.... and/or a very accurate diagnosis.......

KENO wrote: To answer a question before you ask it, it's not something that has to be done, you might call it an enhancement to the installation process be sure it's well seated.

Gary,
Ken is correct but it's interesting that Acme actually recommends lapping. I recommend it on any brand of prop. Who's prop did you get?

Can't decide if the lapping is a joke or not, but I did not "lap" it in.

gary

Ok so I just realized there is a legit video in that thread. I thought you guys were being a bit crazy,(sometimes you can't tell when you guys are bantering with each other - example "Pete lapping is shaft"... - ) but I see it is a real thing. That being understood, do you think I should go back and do this? The prop now has several hours of slalom course runs on it. and it is not vibrating at all. Thoughts?

Gary

I'd leave it alone if you're happy with the way the boat is right now.

If you decide to do it or want to see the whole process look at the thread titled "Proper prop installation".

But beware, there are a lot of pictures of Pete lapping his shaft

Here's a link to it

link