British tenders were small craft of launch to pinnace size. These were used to ferry crews, stores and supplies between shore and the aircraft, to maintain the buoys used to mark out "taxiways" and "runways" and to keep these clear of debris to prevent foreign object damage, and in the case of emergency to act as rescue craft and airport crash tenders. All those functions that on land would require wheeled ground support equipment had a need for a watercraft equivalent.