You need to make a decision about iron wind. On a "delivery trip", I'll
use the engine when speed drops below 4 knots to push along at 5.5
knots ( about 2000 rpm on my 55' monohull and minimal fuel usage). This
strategy provides a pretty reliable 140-150 mile 24 hour run.

When I'm out for fun - it's no engine and no hurry.

Carl