The Dual Identity of a Seaplane on the Water
Years ago in Nigeria, the Federal Inland Waterways Authority decided it had found a golden egg. Its agents ruled that my seaplane was a vessel, which meant my route between Lagos and Port Harcourt was a passage through their waterways, and such passages attract fees. They calculated the bill on the full route distance. I did not argue with their classification. I demonstrated the arithmetic: on a typical flight, my vessel spent about 2,200 feet in their jurisdiction, the length of the takeoff run, before it became an aircraft and left. Billing me would cost more than the invoice would recover. They withdrew the invoice, and I logged the episode under a heading I have used ever since: jurisdictional jurisprudence.
That story earns its keep because it contains, in miniature, the question every harbour master, aerodrome inspector, and port manager asks me first: is a seaplane an aircraft or a boat? The honest answer is that it is an aircraft that must sometimes behave like a vessel, and knowing precisely where one rulebook hands off to the other is the difference between a smooth approval and a decade of committee meetings. This article walks the boundary line, because the boundary is written down in black and white, even if few people on either side of it have read both halves.
The Rules Came from the Sea
It helps to remember which rulebook is older. Marine law had centuries of case history before the Wright brothers flew. When aviation needed rules for machines meeting each other in open space, it borrowed the logic of the sea: give way to the right, alter course to the right when head-on, and the overtaking party keeps clear. Aviation right-of-way rules are marine rules translated upward, so it should surprise nobody that when an aircraft descends onto the water, the two systems dovetail rather than collide.
The marine side says so explicitly. The International Regulations for Preventing Collisions at Sea, COLREGs 1972, define the word vessel to include every description of water craft, including seaplanes, used or capable of being used as a means of transportation on water, and Rule 3 goes on to define a seaplane as any aircraft designed to manoeuvre on the water. Rule 18(e) then assigns us our place in the pecking order: a seaplane on the water shall, in general, keep well clear of all vessels and avoid impeding their navigation. Translation for pilots: on the water, you are the give-way party to everything, from a supertanker down to a paddleboard, and I have given way to both.
The aviation side mirrors the same logic. In Canada, CAR 602.20 requires the pilot of an aircraft on the water to give way to another aircraft or a vessel on its right, to alter heading to the right when approaching head-on, and to keep well clear when overtaking. In the United States, 14 CFR 91.115 says the same. It adds the umbrella instruction that pilots operating on water must, so far as possible, keep clear of all vessels and avoid impeding their navigation: two legal systems, one choreography. A seaplane pilot who learned red-right-returning in a boat and a harbour master who learned the COLREGs on a bridge are already speaking the same language; most of them do not yet know it.
So Which Is It? Follow the Certificates
Having granted all that, I do not accept the folk version, the one that says a seaplane gains speed on takeoff and at some magic moment transforms from a boat into an airplane. Jurisdiction does not work by magic moments. It works with certificates, and the certificates all point in one direction.
Consider the asymmetry. A ship’s captain requires international certification to pilot a vessel, examinations in marine law, and a marine radio endorsement. A seaplane pilot requires none of those things, in any country I have operated in, and I have operated in eighteen. What the seaplane pilot carries instead is an aviation licence, the ability to fly an aircraft certified under aviation airworthiness standards, maintained by aviation engineers, operated under an air operator certificate, insured as an aircraft, and to talk on an aviation VHF radio to aviation authorities. If the seaplane were legally a boat on the water, every one of those arrangements would be wrong, and none of them is.
The tidiest confirmation comes from an odd corner of the rulebooks: wing-in-ground-effect craft, the machines that skim just above the surface on a cushion of air. The IMO and ICAO had to divide those between themselves, and the line they drew is instructive. A craft confined to skimming the surface is a ship and belongs to the IMO; a craft capable of sustained flight above ground effect, as a working figure above 150 metres, is an aircraft and belongs to ICAO. Every seaplane ever built sails over that threshold. In all circumstances and jurisdictions, a seaplane is an aircraft. What COLREGs Rule 18(e) and CAR 602.20 impose is not a change of identity but a change of manners: an aircraft that, while on the water, must follow the right-of-way rules, speed limits, and signals that govern vessels in that particular patch of water—an aircraft for everything else; a vessel for not hitting anybody.
Whose Water Is It? The Jurisdictional Ladder
Knowing what the seaplane is settles half the question. The other half is whose water it is sitting on, and that answer changes every few miles. I think of it as a ladder with four rungs.
The high seas. Beyond territorial limits, under the UN Convention on the Law of the Sea, no one owns the ocean, and no one’s permission is required to land on it. In practice, the high seas are the domain of navies and merchant fleets, not seaplanes, and any pilot who has crossed the Atlantic or the Mediterranean on a windy day and looked down at what we call Big Water understands why. I have landed out there a handful of times, each one a medical evacuation from a ship that could not reach port in time, and it wasn’t pretty. Appendicitis waits for no man.
Territorial and internal waters. From the coastline out, the sovereign state controls both the water and the airspace above it, and that control extends inward to bays, inlets, river mouths, and navigable rivers. Inland, jurisdiction usually passes to provinces and states, unless a federal designation such as a national park or a navigable waterway pulls it back up. This is the rung where my Nigerian friends at Inland Waterways lived, and where most of the world’s seaplane potential lies.
Local waters with local guardians. Island communities, park wardens, and environmental authorities sometimes hold jurisdiction over their own reefs and lagoons, and their interpretations can be creative. A marine biologist in the Philippines once refused me permission to land inside the Boracay reef because the fish would be frightened of a seaplane. I pointed out that seaplanes had landed among the same clownfish and parrotfish thousands of times in the Maldives lagoons without complaint. He replied, without blinking, that those fish were different: our fish are Filipinos. There is no annex in the ICAO framework that covers nationalist fish, so I temporarily moved the operation. Not every jurisdictional ruling can be appealed; some can only be outlived.
Ports and harbours. At the top of the ladder, the sovereign state sets the standard. Still, the port or harbour authority sets the rules, speed limits, signals, and standard operating procedures, and bears the liability that comes with them. Technically, no boat and no seaplane operates inside a registered harbour without the authority’s blessing; if nothing else, a takeoff run would shred the posted harbour speed limit. When I am siting a seaplane operation, I look for harbours before ports: ports carry more restrictions, more regulations, and container ships the size of a city block. This rung matters so much to seaplane operators that it gets its own article later in this series.
Compliance Can Be Bought at a Marine Shop
A war story from the top rung. Ten years after apartheid ended, I was setting up a seaplane operation in South Africa, and we wanted our base in Cape Town’s inner port. Who wouldn’t? The CAA had helped us with the AOC, but the final word belonged to the Harbour Master, and his first word, delivered by telephone, was that there was no way in hell a seaplane was operating in his port. So I bought him lunch. Then I took him and his family on a proving flight around the Cape of Good Hope and landed in his harbour, to let the operation argue its own case. Immediately after, we started devising a plan together.
One of his requirements was to comply with a standard rule that all vessels transiting the port use horn signals. Three short blasts and one long means a ship is backing out of its berth, a manoeuvre performed without the benefit of a backup camera. I am glad big ships have big horns, but no ship’s captain was going to hear anything mounted on my Caravan. So I walked into a marine chandlery and bought a perfectly legal handheld air horn, with the signal codes printed on the side of the can. It rode in my door pocket for years. I offer this as a general principle for operators and regulators alike: most marine requirements that seem like obstacles to seaplane operations can be satisfied cheaply and in full if both sides stay focused on what the rule is for rather than what it says about boats.
The In-Between: Where the Two Worlds Actually Meet
If seaplanes are aircraft in the air and well-mannered guests on the water, where is the real safety problem? In the in-between: the takeoff and the landing, the only phases where a machine doing sixty-five knots shares the surface with machines doing five. This is the moment that scares regulators, and it deserves respect rather than dismissal. A seaplane captain knows that an aircraft in the landing phase has the right of way under aviation rules. The captain of the sailboat below has never read that rule and never will. The rules do not conflict; the perspectives do.
There are two ways to resolve it. The reflex of a nervous regulator is prohibition: ban the seaplanes, or exile their operating areas so far from the traffic that the service dies of inconvenience. The proven alternative is integration, and Canada wrote the textbook. It should tell you something that Canada and the United States, with more seaplanes between them than the rest of the world combined, barely regulate water aerodromes at all. What they regulate is behaviour. Victoria Harbour publishes a joint aviation and marine traffic scheme that defines the seaplane taxi, takeoff, and landing areas as protected when active and open when not, and that simple, ingenious document lets kayaks, whale-watching boats, ferries, and a hundred seaplane movements a day share one small harbour safely. Vancouver Harbour adds a dedicated control tower. Neither solution required banning anything; both required the aviation and marine authorities to sit at the same table and draw the same map. That map, and how to draw one for your own harbour, is where this series goes next, but wait – there is more.
What This Means for You
For the aerodrome inspector: the seaplane never leaves your jurisdiction. Its airworthiness, crew licensing, and operational oversight remain aviation matters on the water just as in the air, so resist any suggestion that the file belongs to the marine authority once the floats are wet. What you should ask of an operator is evidence that its procedures incorporate the marine rules of each site: COLREGs right of way, port by-laws, speed limits, and signals, written into the operations manual and the route guide.
For the harbour master and the port manager: the seaplane on your water is bound by your by-laws and the collision regulations, and a professional operator will arrive already knowing them, sometimes better than the local boaters do. You are entitled to demand horn signals, speed compliance, defined operating areas, and coordination with your traffic scheme, and you should. What you do not need to do is invent a prohibition. Victoria, Vancouver, Cape Town, and a century of precedent show that the sharing problem has been solved, and the solution is a published scheme, not an empty harbour.
For the airline pilot considering the water, your instincts about right-of-way must be rebuilt for the surface. In the air, category and geometry decide who gives way; on the water, you give way to everything, and the discipline is defensive from the moment the floats touch. Learn the marine rules as thoroughly as you once learned the aviation ones, because CAR 602.20 and 14 CFR 91.115 assume you know both, and so does every boat in the harbour.
Where We Go from Here
An aircraft that borrows the manners of a vessel, operating on water that changes owners every few miles: that is the legal identity of a seaplane, and none of it is improvised. The definitions sit in COLREGs Rule 3, the pecking order in Rule 18(e), the aviation mirror in CAR 602.20 and 14 CFR 91.115, and the jurisdictional ladder in the Law of the Sea and a thousand local by-laws. The next article climbs down from the law books. It gets its feet wet: how to find, assess, and win approval for the water itself, from a scouted cove to a certified waterdrome, and why the site selection survey is the most valuable document a new seaplane operation will ever produce.
References
International Regulations for Preventing Collisions at Sea, 1972 (COLREGs), Rule 3 (definitions, including seaplane) and Rule 18(e) (seaplanes to keep well clear of all vessels).
Transport Canada, Canadian Aviation Regulations, CAR 602.20, Right of Way — Aircraft Manoeuvring on Water; TC AIM guidance on operations in harbours and ports.
FAA, 14 CFR 91.115, Right-of-Way Rules: Water Operations.
United Nations Convention on the Law of the Sea (jurisdiction over the high seas, territorial waters, and internal waters).
IMO and ICAO treatment of wing-in-ground-effect craft (division of jurisdiction between maritime and aviation regimes).
ICAO Asia Pacific Regional Office, Regional Guidance on Requirements for the Design and Operations of Water Aerodromes for Seaplane Operations.
Victoria Harbour joint aviation and marine traffic scheme; Vancouver Harbour Water Airport (CYHC) published procedures.
