If you look at the original
diesel tankage of most to all well considered
offshore cruising boats at the 42-50’ range it is around 300-400 liters (I have original 350 liters) - all for a reason. This is what the buyers are looking at.
Solar panels,
wind and hydro generators added a decent more
electrical power over the last 15 or so years but so the increase in the typical
consumption with more devices on board.
This should be more than enough for any serious
offshore cruising sailor. Yes, you sometimes need better
weather planning, patience and performance on maximizing the
sails inventory, trimming etc. For us, the
engine use, in most
remote offshore passages, was to escape or better deal with very bad weather/seas situations, not to speed up whenever we couldn’t get over, say, 4kts under
sails.
As such, we never ended a long
passage with less than 1/3 tank