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Afloat Support

Underway replenishment units represent vital force multipliers, particularly for Australia where practically every conceivable operation must be conducted at considerable distances from shore bases and which will therefore require reach. The RAN possesses one multipurpose replenishment ship, Success, which is capable of transferring fuel, water and limited amounts of food, ammunition and stores. There is also one fleet tanker, Westralia, which is designed primarily for the transfer of fuel and water only, although it can also provide small quantities of food and stores. Resupply of fuel is important not only for the endurance of the ships themselves, but for their organic helicopters. Afloat support ships therefore carry separate supplies of both marine and aviation fuel.

Many constraints on logistic support in the maritime environment are set long before the unit is deployed on operations. The design of the ship, its operational concept, and the logistic support concept, including spares for its whole life, limit the time the ship can remain at sea. Ships have finite storage capacity as well as weight, volume and stability constraints. These characteristics are very difficult and expensive to change once the ship is built. For example, the size of storerooms constrains the amount of food and spares the ship can carry and thus the amount of time a ship can operate independently without replenishment support. These storerooms are difficult to enlarge after construction. In order to ensure that the ship can be supported for its required employment, these factors must be considered during the design phase.

Replenishment at sea (RAS) requirements are a major consideration in warship design. These factors include internal replenishment routes, liquid transfer and management systems, and materiel handling equipment. The design also needs to be compatible with replenishment systems of potential allies and coalition partners, and to incorporate measures to prevent environmental pollution. In the case of warships, there is also the requirement to operate weapons and sensors while undertaking replenishment. When these factors are not given due consideration, the ship requires time away from its tasking to replenish, either in port or at sea.

Ships operate individually or in task groups, and are required to be logistically selfsufficient for the initial periods of a deployment. In addition, ships may have to operate independently of continuous resupply channels, and often without continuous communication links with external supply support infrastructure.

The amount of support carried is based on the endurance expected of the ship and the size of the ship. Endurance is the amount of time a ship can stay at sea before resupply is required. Endurance can vary due to consumption rates and resupply available. RAN platforms range in size from minor war vessels to major fleet units, but all platforms need the same range of support services to function effectively: food, water, fuel, sewerage and rubbish disposal, personnel support, spare parts, and maintenance. Some ships require a greater degree of external assistance than others. Accordingly, the RAN operates its units under different support concepts dependent upon the size and logistics capacity of the unit.

The provision of supplies through underway replenishment ships and the ability to resupply at sea enables fighting units to remain on station for prolonged periods. RAS is a significant force multiplier that extends the range and sustainment of the ship. Afloat support ships provide greater reach and endurance and allow self-reliant and sustained operations to be conducted further away from shore based support. This support may be called upon routinely or as required during operations. The flexibility provided by this concept is particularly important when host nation or contractor support may be insufficient or unavailable. This may be due to remoteness of location, conflict and instability, or diplomatic considerations. The operational role of a maritime unit will be constrained by the ability of the logistic network to provide support to the unit on task. Warships will normally operate in task groups for reasons of operational flexibility, mutual support and to increase redundancy and support options for the Commanding Officer.

Replenishment Ships are specifically designed to support other ships with limited self-sustainment capacity. They carry, and have the ability to deliver provisions and general stores, and they deliver and receive fuel. As a rule, the RAN's replenishment ships do not maintain stocks of repair or spare parts, however, HMAS Success has the capacity to do so if necessary. These ships deliver logistic support, which extends the amount of time major fleet units or task groups can remain at sea beyond their initial endurance limit.