What I mean here is there a formula or chart that will calculate total number of engine hours into actual miles?

There really isn't one. It all depends on the boat and engine package. If you equate a car needing an engine rebuilt at 100,000 miles, the Merc 1075's need to be done at around 100hrs, and on the low end the 502's need to be rebuilt at around 500-600 hrs. But it all depends on the driver and boat. There is alot more torque at 3500 RPM in a boat motor than rolling down the highway at 70 MPH.

Many years ago a study was done, but not on higher revving stern drive marine engines.
Boats with inboard or v-drive marinized heavy duty truck engines were found to have wear factors of about 200 hours equal to about 15,000 miles. Notice I said "about," due to the variables of how the boat was operated, maintained and how heavy the boat.
Since that study there have been many improvements in lubrication and metallurgy that would alter those figures.

Need to know speed to try and convert hours to miles.. It's almost impossible unless you have a GPS that records distance.

Alright,thanks.

Some folks have a 1 hour or better no wake zone-idle to open water.

Others drop right in at a ramp, and are full throttle w/i 100 feet.

It all depends. About 100 hours a year/season is pretty average for many folks; but year round season folks and folks that live on the water usually rack up a bit more.

Am I not underdstanding the question here?

My post answered the question of hours to miles on a land vehicle. Is that what you are asking?

Most people can relate to miles easier than hours because of the odometer on their cars.

Sorry if the question was different.

Mercruiser told me 1hour = 100miles

miles to hours conversion is strictly an opinion and based on a lot of assumptions, i really don't think they'r compatible.

15 hrs WOT is more like 100K miles if you look at wear and tear. I just don't think it's fair to assume.

At first I was shocked at that, but that translates to 200 hours = 20,000 miles which is feasible.