Designing, And Constructing Seaplane Base Facilities CHAPTER 5



A service apron, tiedown area, and administrative building are frequently constructed around or near a seaplane ramp or dock. For safety and convenience, these areas should be separated from access roads, automobile parking areas, and other incidental activity areas either by a buffer zone or by fencing. Effective landscaping to separate airside and landside activities, as well as to improve appearance and attract customers, is recommended.

35. APRON.

The service apron and tiedown area size should be based on five year forecasted need. They should be sufficient to accommodate the based aircraft that will need landside tiedowns plus a conservative estimate of the peak demand for itinerant parking/loading or tiedown positions. A minimum size tiedown or storage area requires approximately one-quarter acre. A service apron normally requires at least one-quarter acre.


Most hangars used for land based aircraft are adaptable for use by waterborne aircraft. Hangars should have a functional and orderly relationship to haul-out and ramp facilities.

a. Location. Hangars should be separated from an administration building and/or the aircraft tiedown storage area to eliminate as much aircraft movement conflict as possible. The service and storage hangar area should be located relative to the ramp or marine railway so that aircraft may be moved to the hangar without requiring relocation of parked aircraft. Both storage and repair hangars should likewise be located so that delivery of materials and access by service personnel will not conflict with aircraft movements.

b. Size. The space required for service and hangar facilities will depend upon the number and the type of aircraft that are to be accommodated. Sufficient additional space needs to be provided for taxiing, turning, and temporarily parking aircraft.


a. Application. Where the shore is steep, a marine railway can be used to move aircraft from the water. The railway consists of a pair of lightweight rails placed on a support structure that slopes into the water. A flanged wheel platform car rides these rails, and a power unit draws the platform up the rails to higher ground. The car will return by gravity if the rail slope is 8:1 or steeper. When the incline is less than 8:1, a reversible power winch rigged with an endless cable will return the platform to the water level.

b. Depth of Toe. In cases where a marine railway is used, it should extend far enough below low water so that the platform carriage is low enough for an aircraft to taxi on the carriage with ease. A platform 20 feet (6 m) wide, 20 to 30 feet (6 to 9 m) long, and inclined at a slope of 7:1 or 8:1, will accommodate most aircraft. The toe of the platform should be able to be lowered 4 feet (1.2 m) below the low water mark. In all cases, depth dimension should be established at the low water level datum established for waterways in that locality.

c. Rail Supports. A system of rails, ties, and stringers supported by bents are an economical means of supporting a marine railway. Pile bents are used in water areas and at points on shore where the soil will not support other types of foundations. Concrete piers or sleepers may be used and at considerably less cost than pile bents if the soil at the railhead is stable and not subject to erosion. A wooden platform will stay submerged if iron and steel are used to fabricate the carriage. The weight of the carriage keeps the platform submerged and prevents the wheels from jumping the rails when aircraft taxi on the platform. The system used for decking a ramp can also be used to deck the platform.

d. Catwalk. A catwalk placed to the side of the bent or between the rails enables persons using the railway to reach the platform regardless of its location along the line. A turntable installed on the platform is a convenient means of turning aircraft.


a. Introduction. Hoisting devices such as a jib crane, pillar crane, or guyed derrick may be used to remove aircraft from the water. These facilities are frequently needed where installations are developed along a high seawall, bulkhead, or steep bank.

b. General Types. Many types of cranes or derricks can be constructed from suitable local materials, or prefabricated steel units can be obtained from manufacturers. Heavy duty hoisting devices are usually powered by gasoline or electric motors; however, a geared hand winch is adequate to lift most light seaplanes.

c. Capacity. Hoisting equipment should be capable of lifting a gross load of three times the maximum weight of aircraft to be handled. Cable and band type slings will be necessary to lift aircraft that are not equipped with hoisting eyes. Types of hoisting equipment and their use vary with the operating needs of the individual site. Detailed information on the capacity, design, and installation of hoisting equipment may be obtained from manufacturers and engineering reference manuals.


a. Multiuse Concept. At basic installations, it may be necessary to use a hangar for both aircraft service and office space. At larger facilities a separate administration building may be required to provide adequate space for the manager's office, passenger and pilot's lounge, display space, restaurant, snack bar, and observation deck. An uncomplicated, functional design that can adequately respond to the administrative needs of the facility is highly recommended.

b. Location. The building should be located in a prominent position on the site, readily accessible to aircraft, as well as to the arrival of customers and visitors from the surrounding community. Visibility of the water area from the administration building is desirable.

c. Outdoor Space. It is desirable to reserve an outdoor space immediately adjacent to the administration building for public use and recreational type purposes. This space should consist of a small lawn or paved terrace, preferably overlooking the shoreline and suitable for informal gatherings. The public area should be physically separated from the aeronautical activity area and/or areas used for fueling or storage of flammable materials.


Access to the administration building or public area, both for customers and for service personnel, should be by an all-weather road. The SBLP (seaplane base layout plan) should reflect the connection to a main highway or street.

a. Roadway Planning. The access or entrance road should have adequate width, serve the anticipated traffic, and permit safe and easy circulation throughout the landside of the facility.

b. Service Roadways. A public highway should never be part of the interior road system of a seaplane base. Vehicular through traffic will interfere with movement of aircraft and can be hazardous to aircraft operations, service personnel and other pedestrians. To permit authorized access and provide circulation routes for emergency vehicles, deliveries of gasoline, oil, fuel, and refuse removal, limited access service roadways are needed. These limited use roadways should be marked and controlled by devices such as removable posts or chains located at the entrance to the areas of aeronautical activity.


Parking space is frequently provided on one or both sides of the access roadway. Either along the access roadway or in a dedicated automobile parking lot, a 9 foot by 18.5 foot (3 m by 5.5 m), parking area should be provided for each car. A 26 foot (8 m) aisle width allows two-way circulation and is general used with 90 degree parking. The parking area should be located for convenient access to the various on-shore and shoreline facilities.


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