Prop question

I am very new to boating. Yesterday while towing a boarder, we heard a crack. I assumed I hit something so we checked the prop. There is a very slight scuff on it. I just purchased the boat I don't know if it was there or not.

So my question is
Is a slight scuff (we didn't even notice it at first) enough to cause vibration

or could it have been anything else motor wise, we didn't notice anything in the water

The scuff won't cause a vibration but it might indicate a hit that might bend the blade a little. IF you feel a vibration in the hull it's worth getting the prop looked at. If you don't feel vibration don't worry.
Usually it will get worse at higher speeds or come and go at different speeds due to harmonics.

Normally you won't hear a crack sound if you hit the prop. It's muffled by the water so it's more of a thunk or thud.

We feel a little vibration and it was more of a thud. I guess I was more wandering if there is any thing else mechanically that can cause vibration that would make you avoid taking the boat out.

We have a Dept finder on our boat. I highly recommend one. It tells you at all times the dept of where you are at and if you are coming up on something (well the one we have does) They range in price from $200 and up. You can get them online or at a local boating store.
My husband seconds the dept finder, it's the most important thing on the boat, if you plan on keeping it around very long.
As for the Vibration, the prop could be bent. Tell us more about it, is it alloy or Stainless Steel?

YES Art is right a scuff could and will cause a vibration usually only at one speed.. props are very well balanced and any time you have the drive shaft running threw the hull of the boat you will feel it if the prop is out of balance by just a hair. More so if you have an all composite boat wich most are now.. You can have the prop pressed and re-balanced... No big deal.. it sounds like a prop to me but you should get it checked out.. good luck