1 knot = 1 nautical mile per hour
D ÷ S = Time (in decimals of an hour)
To convert the decimals into minutes x 60
How long will it take to travel 3.2 nautical miles at 10 knots?
3.2 ÷ 10 knots = 0.32 x 60 = 19.2 minutes
Fuel Consumption: (Power Vessels)
Dependant on your speed, engine type, horsepower etc.
But a good rule of thumb is 1/3 out, 1/3 back and 1/3 in reserve