MARITIME – AFETY, URVIVAL & RECUE CALCULATOR
Man Overboard Drift
A precise tool.
What is the Man Overboard Drift & How does it work?
When a person goes overboard, the vesselβs wind and current continue to act on the body, causing it to drift away from the point of fall. The drift is a vector sum of the windβinduced motion and the waterβcurrentβinduced motion, each of which depends on speed, direction, and the elapsed time.
Wind creates a surface drift that is proportional to the true wind speed and a drag coefficient that reflects the exposed area of a person in the water. Current, on the other hand, moves the water mass itself and therefore transports the person at the currentβs speed and direction. By resolving both vectors into orthogonal components, we can predict the final offset from the original position.
The total drift distance is obtained by combining the windβdrift and currentβdrift vectors over the time interval since the incident. This calculation helps rescuers estimate a search area and improves the chances of a rapid recovery.
Delta x = V_{w}costheta_{w},t + V_{c}costheta_{c},tquadtext{and}quad Delta y = V_{w}sintheta_{w},t + V_{c}sintheta_{c},t
Vw = windβdrift speed (knots) β’ ΞΈw = wind direction (Β° from north) β’ Vc = current speed (knots) β’ ΞΈc = current direction (Β° from north) β’ t = time since MOB (hours)
Parameters
Result
β
Frequently Asked Questions
How do I calculate the drift of a person overboard?
Use the calculator by inputting the wind speed, current speed, direction, and elapsed time to determine the drift vector.
What factors affect the drift of a person in water?
Wind speed, current speed and direction, exposed area of the person, and the duration they are in the water all affect the drift.
Can this calculator be used for maritime emergencies?
Yes, it can help estimate where a person might be drifting to aid in search and rescue operations.
What is the difference between wind-induced and current-induced drift?
Wind-induced drift is caused by surface winds acting on the exposed area of the person, while current-induced drift is due to the movement of water masses.
How accurate is this calculator for real-life scenarios?
The calculator provides a general estimate; actual drift may vary due to factors not accounted for in the model.
Can I use this calculator for non-military vessels too?
Yes, it’s applicable to any vessel where wind and current could affect someone who has fallen overboard.
What should I do if a person goes overboard while at sea?
Immediately notify the crew, stop the vessel, throw life-saving equipment, and use this calculator to estimate the drift for search efforts.
Results are for informational purposes only and do not constitute professional advice.