If the navy was to carry out its operational tasks in the Caribbean, it was not enough to ensure that the ships were manned, and fit for sea: they also had to be capable of fighting. The task of ensuring that they were adequately supplied with guns, and ordnance stores, fell to the Board of Ordnance. Unlike the Navy and the Victualling Boards, it was not a subsidiary board of the Admiralty. It was an independent body, responsible for supplying the ordnance needs of both the army and the navy. The Admiralty could only request that stores be sent out, not order that they should be, in practice an important distinction. The Ordnance Board could be much blunter with the Admiralty than the other boards. This is quite obvious in correspondence about convoys, where the officers of the Ordnance made a number of pertinent criticisms concerning various aspects of convoy sailings, criticisms which applied to all stores being sent from England, but ones which only an independent board had the courage to voice.

The basic method of supply was almost identical to those already detailed with regard to the dispatch of victualling and naval stores. The Ordnance Board ensured that ships fitting for the West Indies had a full quota of guns and stores and, periodically, it dispatched a supply of expendable stores to make good those that had been consumed. Theoretically, this dispatch would be based on the returns of gunners' stores, that commanders in chief were meant to send to the Board. But since these returns were not always sent regularly, problems arose.