CALCULATING TIME SPEED DISTANCE 2011 Time Distance Speed

CALCULATING TIME, SPEED & DISTANCE 2011

Time / Distance / Speed Calculations

Time / Distance / Speed Calculations • All these calculations revolve around the following formula 60 D = T S

Time / Distance / Speed Calculations • T = time in minutes • S = speed in knots • D = distance in nautical miles 60 D = T S

Calculating an ETA

Calculating an ETA • Measure the distance along the course line to the destination in nautical miles

Calculating an ETA

Calculating an ETA • The distance from Ladysmith (top left hand corner) to off Norway Island is 12. 9 nautical miles. • Using 60 D = T S • 60 x 12. 9 = T in minutes = 25. 8 minutes 30

Calculating an ETA • Add this time to the departure time, e. g. 0800 LT, and your ETA off Norway Island will be around 0825 LT.

6 Minute Finger Method

6 Minute Finger Method • This method may be used with either dividers or fingers held a set distance apart for a rapid estimation of distance.

6 Minute Finger Method • At 30 knots the vessel will travel 3 nautical miles every 6 minutes. • Set dividers to 3 nautical miles on the latitude scale, and then run them down the course line counting off 6 minutes as you go.

6 Minute Finger Method

6 Minute Finger Method • Alternatively put two fingers over the 3 nautical miles on the latitude scale, and then run them down the course line counting off 6 minutes as you go. • This will give you somewhere around 24 minutes plus for a time travelled.