Work out voyage time instantly with clear inputs, formula shown and shareable results.
Passage time is distance divided by the speed actually made good, which is service speed reduced by a weather and current allowance of typically 3-8%. Adding port time at each end gives the round figure used for scheduling, chartering and bunker planning.
Voyage time
sea time = distance / (speed x (1 - weather allowance)); total = sea time + port time
Marine results are planning estimates only. Verify against the vessel's approved stability booklet, loading manual, class society rules and applicable maritime regulations before loading or sailing.
Trial speed is measured in calm water. Real passages lose speed to wind, sea state, hull fouling and adverse current.
Log speed is through the water; speed made good is over the ground and includes the current, which is what determines arrival time.