Prop gel coat burn or not??

I wonder if it's possible for the shaft to flex enough so that the prop can hit the bottom of the hull.

It looks like prop strike scars on the backs of manatees.

Thanks.
While the prop is in, I will go ahead and get it trimmed down. It looks like I have been pushing the limits. I have been VERY happy with the prop. The boat will throw your head back at all speeds. Maybe it will run even smoother after the change.

I will try for 1'' to 1.5'' clearance

I do now concure with Billy. The gouges do look like they are from the prop.

I dont know that you will get an 1", I measured my 75 mustang over the weekend and it only had 7/8" max with a 12" prop. The 13" 540 would have left me with 3/8". Even with the 12.5" I will only have 5/8" clear.

I am mailing the prop to ACME in Michigan today.   It is in for basic repair and also they are going to take off a .5 inch and make it a 12.5'' (just like the new ACME 1210 model). I will reply back and let everyone know how much clearance I have after that.

I pulled the prop off last night. The strut and everything are rock solid (as I pulled hard on the wrench to get the last torque on the puller).

I have only been out 3 full ski days this summer. The boat feels fine as wine. I have never had any problems with the 540. I have LOVED the prop for 3.5 years. Although the boat is like a 1970s muscle car and not a $50,000 new Nautique.

I hit a piece of firewood in the lake. I found it afterward. It was water logged with soft exterior. I don't think the scrapes came from it.

It is a mystery. The scrapes were not there last year. I have always been a little conscious of the close clearance. The distance between the two scrapes is too far. I would bet I got into some small rock of the right size to do it. Although the shape of the scrapes does tend to look like repeated revolution hits intead of a one time debris slam.

THANKS GUYS for the input and conversation.

My boat has the same marks. Previous owner hit something bending the strut shaft and rudder, prop strike caused it. Those cuts look old, sure they werent there from before? Also, they are out of line, like they were caused by 1 or 2 revolutions from a very bent shaft and propeller, just like mine.