Ship to Ship Oil Transfer

What is STS or ship to ship transfer?

A STS or ship to ship transfer refers to the transfer of ship’s cargo, which can be oil or gas cargo, between two merchant tanker vessels positioned alongside each other.

Either the ships can be stand still or the STS operation can also be performed while ships are underway. But it requires proper coordination, equipments and approval to perform such operation. Both the masters of the ships are responsible for the entire STS operation


As Per Resolution of MEPC (59) a new chapter 8 is added to MARPOL Annex I for prevention of pollution during STS operation between two ships.

This new regulation is applicable for oil tankers of 150 GT but bunkering operation and oil transfer operations for fixed or floating platform has been excluded.

Following are the requirements for conducting Ship to Ship transfer operation:

  • Adequate training of oil tanker’s staff carrying out the operation.

  • Proper STS equipment to be present on both the vessels and they should be in good condition.

  • Pre planning of the operation with notifying the amount and type of cargo involved.

  • Proper attention to the difference in freeboard and listing of both the vessel while transferring oil.

  • Taking permission from the relevant port state authority.

  • Properties of Cargo involved to be known with available MSDS and UN number.

  • A proper communication and communication channel to be set up between the ships.

  • Dangers associated with the cargo like VOC emission, chemical reaction etc to be briefed to the entire crew involved in transfer.

  • Fire fighting and oil spill equipment to be present and crew to be well trained to use them in emergency.

  • All guidelines to be followed as per MEPC 59, MARPOL Annex 1 chapter 8, SOPEP, SMPEP, STS transfer guide and operational plan.