Interesting thread. I never really thought about a conversion between the two. I think the 100miles to 1hour one would probably work out about right unless someone really kept the hammers down a lot. For me Boating primarily at Loto I spend a lot of time at idle so that really affects my hours.

If you use Royal Purple 15W40 and MerCruiser oil and fuel filters, your engines will last longer, run cooler, wear out slower and make horsepower. Change all of them at 100 hours for naturally-aspirated engines and 50 hours for supercharged engines. You'll be stacking the deck in your favor as well as you can.

Yes Ed that's what I was asking.For example,how many "land miles" are on a boat motor with say,40 hours on the hour meter.

I ask this because my new boat with a repower 2 years ago has 40 hours on the engine.This last Memorial day weekend we were out on the water for two days at WOT when we were using the boat and the rest of the time was moored up in the no wake zone.Just under 2 hours were put on the boat that entire weekend.I was just curious how many land miles were put on the boat.So I think I have my answer...1 hour equals 100 miles.

If you were WOT the whole time I would figure a few more miles. I bet I don't go WOT for two hours in a couple of seasons.

Also, Don't forget about warm up and cool down time. Let everything get to temp. before you start slamming on the sticks and let her cool down before you shut her down.

yep