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Aviation History
1963
1963 - 1105.PDF
Air-Cushion Vehicles FLIGHT International supplement, 28 March 1963 BERTHING AND HANDLING OF HOVERFERRIES . . . feature of the coastline, as their slope and level is often dependent upon prevalent wave conditions. A beach that is perfectly suitable on one day may have disappeared the next. The likely range of beach move ment on the chosen site much be investi gated to ensure that it is within the capa city of the ferry; and the permanent facili ties, such as the berthing platform itself, must be designed so that the craft can operate under varying beach conditions. Earth-moving equipment should be avail able to make local adjustment to the slopes of beaches and approaches to berths. There must be sufficient land available be hind the beach for the ferry to be driven to a berth where it can be loaded and turned well clear of high water even under storm conditions (Fig 2). On accreting coastlines such sites are not difficult to find, but they may not exist at all on coasts where erosion is active, or on rocky coasts. In these cases artificial slipways will be needed, with some form of shelter to ensure an accurate approach (Fig 3). Such slipways would probably be built first within existing harbours, at less cost than deep water berths. Later they could be built with their own breakwater protection on coastlines previously not provided with harbours. The amphibious hovercraft has the addi tional advantage, helpful to rapid berthing and cargo handling, that it can be driven ashore and berthed firmly and accurately against a platform at deck level. Fig 4 illustrates possible loading methods. If a side-loading vessel is driven between two platforms (A) loading and unloading may proceed simultaneously. This pro duces a very rapid turn-round but imposes a "gauge" on the craft and also compli cates the traffic flow arrangements, as hovercraft and vehicle tracks are crossing. In method B the new load must wait whilst the old load is disembarking but this slight delay is probably offset by the greater flexi bility given to the hoverport design. End loading methods illustrated in C and D would be suitable for small craft berthing in protected waters but the bow doors would not be used for sea-going vessels. The straight-through loading method shown in C gives fast traffic handling but involves more awkward manoeuvres than arc required by the single-ended loading (D). Generally, therefore, layout B seems pre ferable. If the conventional ferry loading rates for cars and passengers are used it can be readily shown that hoverferries of this size could be turned round in less than 15min. including refuelling time. This very short period, only a fraction of that required by conventional ferries, is made possible by the special characteristics of hovercraft rather than by unusual cargo-handling methods. TIDE.IUWGE i J H.W.O. S.T. t4Tlie.lL SU'SEC SECTION EXAGGERATED VEMICAL SCALE Fig 3 Layout of hovercraft berth on cliff'girt coast Rigid-sidewall Craft These vessels are likely to be economical for runs in moder ately and well sheltered water. Where the shelter is very good, as in rivers, they may be berthed alongside conventional pontoons but if any appreciable swell is expected then greater economy of operation would be obtained by using the type of berth illus trated in Fig 5. A unique feature of the hovercraft may be used to achieve a positive ship-to-shore connection, namely, the vertical movement of the craft when it changes from hovering. By using this device the craft may be berthed on the submerged floor of the floating pontoon, which is positively con nected to the shore with a long hinged ramp and firmly restrained between piled dolphins. The craft will enter between adjustable fenders and settle on the open-grid pontoon Fig 4 Diagram of loading methods SIDE LOADING 'L ^]fJSZ3L^ S • u"n- EWD LOADING 38
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