David
Zagaynov

A flying boat, a Berkeley kid, and a math problem nobody wanted to solve

David Zagaynov runs a company whose whole pitch sounds like a dare. Build aircraft with no landing gear for runways. Let them take off from open water, from oil rigs, from coastlines that never see a tarmac. Name them after birds. Fly them from a laptop over Starlink. Then point them at the largest, most contested ocean on Earth.

That company is Poseidon Aerospace, and Zagaynov is its CEO and co-founder. He started it in 2023 with Parker Tenney, a former Lockheed Martin engineer, and Isaac Baumstark. Their shared fixation was not a market or a margin. It was a machine - the ekranoplan, a Soviet Cold War-era hybrid of boat and plane that skimmed just above the surface of the water, riding a cushion of air the engineers called ground effect. Western intelligence once nicknamed the things sea monsters. Then the Soviet Union collapsed, and the sea monsters mostly rusted.

Zagaynov could not let it go. "We thought that this is incredible technology," he said. "Like, why isn't it around right now?" Most people ask that question, shrug, and move on. He raised money on it.

Before the seaplanes, there was a year of code

The origin story does not begin in a hangar. It begins in a lecture hall at the University of California, Berkeley, where Zagaynov studied computer science. His father was an immigrant who built his own software engineering firm, so the idea that you could simply start a thing and own it was less a leap than a family inheritance. As a high schooler, he watched HBO's Silicon Valley - the satire, the absurd startup mania - and somehow took it as encouragement rather than warning.

After Berkeley, he did the expected thing. He went to Amazon and wrote software for about a year. By his own account, it did not take. He has said he wouldn't be caught dead doing that work anymore, which is a striking thing for a freshly minted engineer with a comfortable salary to say out loud. The complaint was not technical. It was existential.

Incremental efficiency gains in some backend pipeline were not it. A flying boat that could resupply an island, an oil platform, or an aircraft carrier - that was. By one account, the spark struck during San Francisco Fleet Week in 2023, watching the Navy's Blue Angels carve the sky over the bay. The question that surfaced was childlike and stubborn: why can't we build planes? He met his co-founders through mutual friends around the same time. The roommates became a company.

The fleet is a flock

Poseidon's aircraft are named with a naturalist's restraint. No thunder, no spears - just birds that live where land meets water. The first to fly was the Seagull, an unmanned carbon-fiber sea glider with a 13-foot wingspan, a quarter-scale proof that the physics held. It carries a modest payload, somewhere around 50 to 100 pounds, and it exists to answer a single question for investors and the Navy alike: does the thing actually skim?

The grown-up versions, Heron and Egret, are built around a single number that Zagaynov keeps returning to: cost per flight-ton-mile. Each is designed to haul up to two tons of cargo as far as 1,500 miles. The Heron is a seaplane, meant for water and coastline. The Egret is a short takeoff and landing aircraft, meant for the half-built airstrips of the world. Both are unmanned. Both are flown remotely. The pilot's office can be anywhere with a signal.

Strip away the romance of the sea monster and what remains is a logistics argument. Poseidon frames its whole reason for being as driving down the cost of moving a ton of cargo a mile, and it intends to start where the incumbents won't bother - remote communities and underserved routes that big freighters treat as rounding errors. A purpose-built airframe, the thinking goes, beats a decades-old plane retrofitted for a job it was never designed to do. Carbon fiber instead of aging aluminum. No pilot, no pressurized cabin, no expensive runway. Just the cargo and the cheapest possible physics.

That physics is the part most people miss. Ground effect is not a trick; it is a real aerodynamic phenomenon. Fly a wing close enough to a surface and the air trapped beneath it behaves like a cushion, suppressing the swirling vortices at the wingtips that normally bleed away lift. The result is more lift, less drag, and better fuel economy - if, and only if, you can keep an aircraft stable a few feet off the waves without dunking it. The Soviets built leviathans on this principle, including the so-called Caspian Sea Monster. Poseidon's wager is that modern autonomy, sensors, and satellite control finally make the idea practical at a sane size.

From stealth to eleven million

The money followed the prototype. Poseidon raised a $1.4 million pre-seed round led by Starship Ventures, emerged from stealth with a video of the Seagull on the water, and then, on November 5, 2025, closed an $11 million seed round led by Tamarack Global. The cap table reads like a defense-tech who's-who: Draper Associates, Starship Ventures again, Drover Ventures, Cade Ventures, GoAhead Ventures, Fortitude VC, and a roster of angels. Total raised to date: $12.4 million.

With the cash came a footprint. Poseidon keeps its headquarters in San Francisco, a satellite office in Washington, D.C., where the defense conversations happen, and a manufacturing facility in Brunswick, Maine, where the aircraft get built far from any startup cliche. The company has signed a CRADA - a cooperative research and development agreement - with the Naval Surface Warfare Center Panama City Division, which is the government's polite way of saying it is paying attention.

The geography is its own kind of statement. A software founder who wanted comfort would have kept the whole operation inside a single San Francisco office. Zagaynov instead spread the company across three corners of the country: the engineering and capital in California, the customer in the capital, and the actual building of carbon-fiber airframes in a Maine boatbuilding town that has spent generations making things that go on water. For a startup whose product is half-plane, half-boat, that last detail is almost too on the nose.

Two oceans on the whiteboard

There are two stories Poseidon tells, and they share an airframe. The first is commercial and almost gentle: food flown to archipelago islands, supplies dropped to offshore rigs, routes that conventional cargo carriers find too small, too remote, or too unprofitable to bother with. The math of air cargo, Zagaynov argues, has been broken for decades, weighed down by aging planes built for a different job.

The second story is sharper. Poseidon's own materials sketch a defense future in which runway-independent aircraft project American logistics across the Pacific - to Taiwan, to Guam, to allies in Korea - precisely because they don't need a runway an adversary can crater. It is the kind of dual-use pitch that makes a seaplane startup suddenly very interesting to people in Washington. In January 2026, Zagaynov was billed to speak at Apex Defense on the unglamorous, decisive problem of sustaining forces in a contested, dispersed theater.

The proof, as always, waits on flight. Heron and Egret are scheduled for testing in mid-2026. Until they fly at scale, Poseidon is a thesis with very good renderings and one small carbon-fiber bird that has touched the water. Zagaynov seems comfortable with that. He has bet his twenties on the idea that the most interesting place for an aircraft to live is the few feet of air just above the waves - the exact margin the Soviets found, and the West forgot.

It is a strange thing to be obsessed with. That is rather the point.