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4 August 2008
Why Seaplanes?
Informal suggestions by Ken Fletcher
on seaplane transportation through 1945 (inspired by many sources)

Why Seaplanes?
by Ken Fletcher

Why are seaplanes so important in the Spontoon Island Archipelago?
(And for international air travel, through the 1930s?)

No investment in building a landing field is necessary. You may land your aircraft at remote, undeveloped locations that have about a half-mile of relatively calm water with about 1 to 2 meters of depth, such as:
     On a smooth, straight RIVER
     On a medium sized LAKE
     Within a protected HARBOR or LAGOON (either undeveloped areas or at seaports)
     And even on a moderately calm OCEAN (in coastal areas, near islands, or open ocean)

Most of the major cities and government centers in the Pacific Ocean region are seaports on the ocean, or built on lakes and rivers. Seaplane bases are relatively inexpensive to construct close to these large cities.. Many of the trade centers in the Pacific and the sources of raw materials are also near ocean, lakes, and large rivers. A seaplane base can be relatively quick to construct.

Much of the Spontoon Island Archipelago consists of reefs, shallow ocean banks, and atolls with surrounding islands and lagoons. It is difficult to find a half-mile or kilometer straight run of flat, cleared land on most of the islands, and it is usually difficult to land and supply heavy construction equipment. Regular airport runways for wheeled aircraft are unusual. (Wheeled aircraft might emergency land on (and take off from) flat, wet & firm low-tide beaches, but this could be very risky, determined by the beach and tide.)

With most of the islands in the Archipelago surrounded by shallow water, and having sheltered lagoons, there are many locations available for basic and elaborate seaplane ports for rapid transportation of passengers and express cargo. Seaplanes have been a useful fast transport supplement to the traditional small sailing canoes & boats and small power-schooners (which are still used).

Transferring cargo & passengers:

Seaplane hulls & floats have to be protected from punctures.  They are strong for their weight, but can be damaged if they hit driftwood or snags, or rocks or coral. Mooring areas have to be carefully checked for obstacles under the water. As best one can, the landing and take-off waterways have to be checked for floating debris. Like a boat, the hull has to be protected from hard repeated contact with a pier. A seaplane is not as sturdy as most boats, but can be just as versatile in unloading cargo.

With care, a seaplane can be beached on sand or pebbles (but I don't think that would be recommended).  Cargo may unload directly on a beach or waded-in.

A Seaplane may be anchored or moored like a small ship. Most seaplanes will carry a lightweight anchor and anchor-line, and will have equipment for mooring to a stationary buoy or pier-side.

Seaplanes can unload cargo alongside into canoes, rowboats, and small motorboats for transfer to land or other boats (or seaplanes). Cargo can also be loaded into cargo nets hanging from cargo cranes of larger ships.

Seaplanes can be moored to piers and unloaded. Most often, low floating piers are used (sometimes with taller piers), to allow for tides, and allow the seaplane's wings to extend over piers so the seaplane hulls can be within easy reach of the pier-side for loading.

Amphibian (wheeled) seaplanes may be taxied up a wood or concrete ramp from the water, and unloaded on a wooden or concrete landing platform.

Navigation, Safety & survival in a seaplane:

For any aircraft flying over the oceans: until the 1940s aircraft equipment and support is only partially reliable. That includes aircraft structure, motors, navigation methods, radio, & weather reports. Radar does not exist.  Reliable engines, safe for long distances, were not really available until the late 1920s. It will be the late 30s before most designs are reliable for long operation. Navigation over the ocean is theoretically possible but very dangerous if you are traveling over long stretches of empty ocean. Navigation is done with magnetic and gyroscopic compasses, sextant sightings of the sun, moon, or planets, compared to an accurate time. Calculations are then done with a reference book and a sliderule, with additional calculations done with pencil & scratchpaper. Any small degree of error in sextant observation could mean a position off by 50 miles after 5 hours of flying, when you might not be able to see an island over 8 miles away. In 1938 Pan Am Clipper navigators were making sextant observations and calculations every 15 minutes continuously for 13 hour flights! Winds could blow an aircraft sideways from its course, even though the compass setting would remain correct. Such drifting was more difficult to judge over the ocean, with no fixed references below. Over the ocean, radio signal direction finders were nowhere near as accurate as everyone pretended they were. Radios were not really sturdy. Non-repairable parts would break in flight. Weather reports were from your departure point, your destination, and possible ships that might report weather on your route. Ocean weather maps were just beginning. You were more likely to see your weather a short distance ahead, than hear about it in a radio report.

Unless you were short-distance island-hopping, with a reliable map, it was easy to get lost over the open ocean. Pilots did get lost, miss the target of their island destinations, and did run out of fuel, or their airplane might have a mechanical break-down over water.

An emergency landing on water was more survivable in a seaplane.  It is designed to land on water and float! Once down on the water, it might be possible to repair damaged parts, and you may be able to take off again. (Some planes that couldn't take off from the water taxied on the surface for hundreds of miles.)  If your motor is disabled, you may stay in your floating seaplane and use the radio (if it works).  Once you have landed on water, you may have time to transfer to a liferaft or lifeboat, and transfer emergency supplies. Your floating seaplane is more visible from a distance. Your cargo (mail pouches, etc.) may be salvageable from a floating seaplane. Seaplanes are generally larger than landplanes and have more space for emergency equipment.

Huge seaplanes might have a tiny boat on board for the crew. Large seaplanes are likely to have liferafts for all aboard and an inflatable raft that the crew could use to row to a buoy or get onshore on their own. Inflatable (CO2) flotation bags (for the aircraft!) were often included in emergency equipment. Lifejackets were common. Seaplanes were usually designed with waterproof floatation compartments, and gasoline fuel tanks (full or empty) added floatation.

Seaplanes are a more survivable tool for flying over the ocean in the 1930s.

What do seaplane flying services do?

Commercial scheduled airlines:
(on a schedule, long-distance across-ocean (trans-Pacific, etc.), between specific major cities):


In the 1930s, mail (Government mail or business mail) is the main reason for having a scheduled airline route. Most often, an airline was subsidized by a government (or several governments), with money above the revenues from mail postage, to pay for flight costs plus a profit. A subsidized airline could be profitable just for providing mail service. (Imagine the information that Washington DC and New York businesses would want sent to and from Hong Kong via airmail). Airmail might take only 8 or 9 days (!) A surface letter might take 6 weeks by ship.

Mail also includes Express Freight: Objects that have to move fast: Urgently needed repair parts, perishable vegetable goods or animals, things that are high value for their weight, such as bonds, cash, gems, gold, entertainment (news, newspapers, magazines, film, audio records).


Passengers on scheduled routes (usually between major cities, but also travelling to transfer points). It is assumed speed of travel is required, and cost is no object:

Business people (Rich owners, or executives working for a rich company).
Diplomats & high-ranking colonial officers.
Military officers (if military flights are not available).
Rich travelers looking for fast novelty travel.
Airline employees (from management to aircrew to laborers at air stations).
Emergency charity transportation. (medical emergencies, as one example)

Frivolous fantasy adventure stories will add more categories:
University Archeologists would be an example.

Short-distance scheduled airlines exist between islands in the Spontoon Island Archipelago and the other island groups in this version of the Pacific. Such carriers might be more economical than the trans-Pacific airlines, and also be more likely to carry the standard adventure-story passengers.)

Commercial charter (non-scheduled) airlines:

These provide fast (& maybe expensive) taxi service between seaports, islands, coastal areas, & ships.  These may be round-trip flights, or one-way.

These services most often will be:

Express freight such as construction machinery equipment, repair parts, valuable raw commodities, etc.
Information and mail.
Aerial Observation: Mapping, aerial photography, geological survey, fishing survey & fisheries spotting.
Passengers: businesspeople, repair technicians, diplomats & colonial officers, military officers (when military flights are uneconomical), & medical staff. Air trips may be one-way or two-way. Charter passengers for shorter flights to-and-from seaports are more likely to include the typical fantasy adventure passengers: University Anthropologists, Zoologists, Missionaries, Wives of Plantation Managers, Entertainers, Young Tourist Couples, etc.
Medical services: medicine, evacuation ambulance, nurses & doctors.

Private (non-commercial) seaplanes:

These could exist, but would be unusual. One could include aircraft owned by businesses or business co-operatives, used only for the businesses' passengers and freight. In the Spontoon Archipelago, there might also be seaplane "rich people's toys" or "air yachts". There would be some aircraft dedicated to civilian pilot training, and used by the civilian air pilot schools.

Aircraft are very expensive to fly (fuel & oil) and to keep in mechanical repair. Repair expenses can be sudden, and very expensive. Most private aircraft (that are not owned by the rich), are likely to be informal commercial charter aircraft, available for hire, when not needed for the owner's business. Work-for-hire might include sightseeing, guided fishing & island-camping expeditions, & smuggling.
Military & Coast Guard Seaplane services:

Sea Search: for rescue and military intelligence: Spot, map, identify.
Sea Rescue: Drop supplies, direct rescue ships, pick-up survivors. (In a civil emergency, such help would be expected of civilian aircraft.)
Exploration: Aerial photos, check maps, drop-off explorers and pick them up. In some isolated areas of the Pacific, this was being done through 1960. (An excellent cover for spying.)
Courier: Messages, orders, & maps between Military bases and ships at sea.
Utility: Light priority air freight (such as electronic parts) between Military bases and ships at sea.
VIP Transport: Officers, spies, diplomats between Military bases and ships at sea.
Ambulance: casualties to medical care; medical care to casualties.
Espionage: Aerial photos, check maps, drop-off and pick-up agents.
Naval Warfare: Aerial photos, check maps, search for enemy ships, targeting & spotting for naval guns, attack (torpedo, bomb, strafe), escort convoys, ferry high-priority personnel and supplies, drop-off and pick-up raiders.

Military Seaplanes can operate from very primitive seaplane bases: A sheltered cove with fuel storage is enough for a temporary base. This allows for aircraft to be dispersed, especially among atoll islands. Seaplanes can also operate with warships, including specialized seaplane tenders. They can fly with (or be carried by) warships on naval operations.

Air Exploration:

By the late 1930s, most of the Pacific Ocean area has been at least superficially explored. Almost all the islands are located, almost all the inhabitants have been met. It might still be possible for a trader or anthropologist to fly to a Pacific Island that has had minimal contact with European-style civilization.

When seaplane routes and facilities are planned for new locations, there are often "Survey Flights" (done with the aid of ship-based expeditions) to photograph & map potential landing areas and check water and weather conditions. This might be an on-going activity for commercial airlines, and is a good cover for gathering geographical information & military intelligence.

Advantages of smuggling with seaplanes
(Commercial, Military, & Freelance):

Speed: Fast movement of valuable cargo. Outrun patrol boats.
Avoiding customs officers at seaports: Transfer of smuggled goods at isolated beaches, coasts, harbors, lagoons, & islands.
Flexible rendezvous for transfers: On open sea or sheltered water with canoes, boats, ships, other seaplanes, & submarines.

Seaplane types:
Flying boats -- a boat-design hull, often with a "V" bottom. Often for stability there are 'sponsons' (wide sections of hull at the waterline) or 'waterwings' (short & stubby wings at water-surface level that are often used for fuel tanks).  Often there are also small pontoons (floats) at the end of the wings (these keep the wingtips out of contact with the water.

Floatplanes -- An aircraft, often of standard design, with one or two large floats replacing the usual wheels for landing gear. A floatplane with a single float will often have 2 floats at the end of the wings to protect the wingtips.

Amphibian --(sometimes called Amphibion): A Flying boat or Floatplane with wheels (usually retractable) on the hull or floats, so the aircraft can choose to land on a regular airfield.

Original version-- November 1997 and printed in Spontoon Island Guide #1 in 1998.
Revised and expanded June 2007, November 2007, March 2008, August 2008.