Underway Replenishment (UNREP) at Sea

Posted on Oct 18, 2024 in Social sciences

Definitions

Supply Unit (Replenishment Unit)

A group of vessels composed of providers, recipients, and rescue support.

Ship Control (Control Ship)

The vessel that controls the operation of the RAS unit.

Ship Guide (Unit Guide)

The vessel that maintains the course and speed for the approach and ensures other vessels approach safely.

Approaching Ship

The vessel that makes the approach.

Supplier Ship (Delivering Ship)

The vessel that initiates the maneuver.

Receiving Ship

The recipient of the maneuver.

Provider Supply Vessel (Supplying Ship)

The vessel that provides the elements to be transferred.

Customer Ship

The recipient of the elements that are transferred.

Unless otherwise ordered by the OTC, the Control Ship will always be the Guide and the Supplier, while the Approaching Ship is the Receiver. The Supplier Ship initiates the maneuver and does not necessarily provide the material.

Procurement at Sea: Organization and Control

Tactical Officer Commander (OTC)

The OTC is the senior officer responsible for the replenishment operation. Although responsible for the implementation of the RAS, the OTC should consider the views of other commanders. If the OTC is the Force Commander of Supply, they must generally comply with requests from the commander of the fighting force, such as the time and situation for the rendezvous and direction during provisioning. If the OTC is the Force Commander of Combat, they must carefully consider the recommendations of the Force Commander Supply, such as course and speed of transfer. The following paragraphs are based on the consideration that the OTC is the Force Commander of Combat.

Procurement at Sea: Major Force Procurement

The senior supply officer maintains a direct link with the commander of the fighting force regarding procurement and is responsible for:

  • Prioritizing the procurement of ships.
  • Recommending to the OTC the course and speed under optimal conditions for the supply.
  • Warning the OTC of any special limitations or vessel characteristics of their group, which could affect the supply or the sequence of RAS operations.
  • Exercising responsibility in the movement of supply units that target the rendezvous area and initiating movement reports when necessary.
  • Ensuring that procurement units in the group follow the OTC’s instructions on the rendezvous point, type of training, course, speed, communication plan, and degree of readiness for combat.

Procurement at Sea: Major Combat Force

The senior officer or commander of the force that will be provisioned must:

  • Choose and communicate the time and place of the rendezvous as soon as allowed by the procedure.
  • Coordinate requirements with the Force Commander of Supply but allow each ship to make specific requests to a tanker.
  • Ensure that the agreed-upon sequence of supply vessels is enacted and controlled, taking into account any last-minute changes to the fixed supply sequence.
  • Coordinate the transportation and sequence of passenger and mail flights and establish the priority in allocating them to the ships of the force or combat force that need to be distributed from the supplier.

A supply unit is defined as a group of ships consisting of one or more vendors, one or more receivers, and/or standby vessels and/or rescue units (SAR).

Within the supply unit, the following definitions shall apply:

  • Ship Control: The ship controlling unit RAS operations.
  • Unit Guide: The supply unit guide.
  • Delivering Ship: The provider rig.
  • Receiving Ship: The receiver rig.
  • Approaching Ship: The ship approaching or already alongside.
  • Supplying Ship: The ship transferring the goods.
  • Customer Ship: The ship receiving the merchandise.

These definitions are general. Unless otherwise ordered, the Ship Control will be the Unit Guide and the Delivering Ship. When this is not the case, the OTC shall assign these functions to more suitable vessels. Similarly, the Receiving Ship will usually be the Approaching Ship. It should be noted that the Delivering Ship (rigging supplier) will not necessarily be the Supplying Ship (transferring goods).

Civilian Auxiliary Vessels: Command

British supply ships belonging to Germany (Royal Fleet Auxiliary’s), as well as some U.S. Navy and German Navy vessels, are manned by civilian staff. A small group of U.S. Navy personnel embarked on such vessels maintains communications equipment and is trained in both NATO communications procedures and RAS. When these vessels are used in a supply unit, they should be considered non-combatant, so the Ship Control must be a combatant vessel.

Procurement at Sea: Planning

The overall effectiveness of a RAS operation depends on the care taken during the planning phase. A pre-conference is recommended whenever possible.

Factors

  • Estimate of Needs: The commander of the combat force must provide the Force Commander of Supply with an updated assessment of the solid and liquid load needs of the fighting force.
  • Rate of Transfer: The desired rate of transfer should be considered.
  • Difficulties in Scheduling: Avoid last-minute changes in the supply sequence, as this could cause a long delay in the trip.
  • Primers: Use the maximum number of primers for the maximum transfer rate.
  • Passengers and Correspondence: Plan for the transfer of passengers and mail.
  • MSCOM Conditions (Communications Restrictions): Consider any communication restrictions that may be in place.

The standard formats for ordering supplies are in the MTMS (Maritime Tactical Message System) (APP-4).

Method of Implementation:

  • OPSTAT RASREQ: Used by warships to communicate their needs. It is sent directly to the supplier or the OTC.
  • OPTASK RAS: Used by the OTC to enact the procurement program.
  • OPSTAT RAS: Used by providers to inform recipients of the details of their gear and the types of goods that can be transferred from their stations.
  • OPSTAT UNIT: Used by all ships to mark the details of their transfer stations.
  • OPSTAT CARGO: Used by providers to inform the OTC of their position after a supply operation or a change of operational control.

Phases of the Maneuver

Stages of the Maneuver

The various phases of supply at sea between two vessels are:

  1. Preparation
  2. Approach
  3. Maneuvering
  4. Station Keeping
  5. Transfer
  6. Completing the Maneuver
  7. Separation

Glossary of Procurement

  • UNREP (Underway Replenishment): Provisioning at sea.
  • CONREP (Connected Replenishment): Supply connection.
  • VERTREP (Vertical Replenishment): Vertical supply.
  • RAS (Replenishment at Sea): Transfer of weights.
  • FAS (Fueling at Sea): Oil at sea.
  • Standard Tensioned Replenishment Alongside Method (STREAM): Constant voltage method.
  • Standard Underway Replenishment Fixture (SURF): Astern.
  • High-Line Rig (USA): Lifts.
  • Manila High-Line (USA): Abaca lifts (light and personnel).
  • High-Wire Line (USA): Cable lifts (medium and heavy).
  • Light Jackstay (UK): Lifts out (usually abaca) (light and personnel).
  • Heavy Jackstay (UK): Cable lifts (medium and heavy).
  • Span Wire: Cable lifts for oil hoses.