Its interesting that you ask about cost per unit distance. Wind
is free, so distance is almost irrelevant. You can cross an ocean without using any fuel.
However, you must eat, cook, drink water
, be entertained. IMHO, most people think of cost per unit of time. How much $ per month for example.
Coming full circle back to distance, my rule
of thumb is 1000 miles a week, and 100 miles a day. That applies for passages. For coastal cruising, assume 5 knots and about 10 hours a day, so 50 miles is a good day.
These general rules of thumb used to truly annoy a skipper
friend of mine. 100 miles a day does not equal 1000 miles a week. 5 knots does not equal 100 miles per day. Also, it does not consider the size of boat, hull speed
, rig, etc. What truly annoyed him though, was that using that rule
, I was able to predict the time required for us to cross the atlantic ocean
, correct within a few hours. I believe he started the engine
to WOT on the last day just to be sure I wasn't exactly right...which would have killed him, figuratively.
I believe I got those numbers from a sailing book, but can't remember who said it.