A flatpack, solar-electric SWATH seastead that ships in one 40-ft container and assembles for two people living independently on the water.
The Tern distills your full-size trimaran/SWATH vision into a producible, shippable kit. It keeps the three NACA-profile legs, triangular truss living area, rim-drive propulsion, and solar-electric DNA—scaled so every structural member fits inside a single 40-ft High Cube container manufactured in China and bolted together in the Caribbean.
| Hull Form | 3-Leg SWATH (Small Waterline Area Triple Hull) |
|---|---|
| Overall Length | 22 ft (living platform) / 16 ft beam at aft |
| Legs (3x) | 14 ft length × 6 ft chord × 1.5 ft width; NACA 0030 profile; 5° sloped toe at bottom |
| Submerged Draft | ~7.5 ft per leg (50 % submergence) |
| Displacement | ~14,000 lb total buoyancy (3 legs) / ~4,500 lb operating weight |
| Living Area | ~160 sq ft triangular truss; 6.5 ft headroom |
| Propulsion | 4× compact rim-drive thrusters (12" Ø) — 2 on center leg, 1 each wing leg |
| Stabilization | Passive winglets on outer legs + 1 active pitch stabilizer on center leg (8 ft span, MVP version) |
| Mooring | 3-point helical screw anchors with 3/8" synthetic tension legs |
| Solar Array | 1.8 kW (6× 300W panels) over roof |
| House Battery | 10 kWh LiFePO4 bank / 3 kW pure-sine inverter |
Packing arrangement (lengthwise)
Every piece passes through the container door (2.34 m × 2.58 m). Longest member is 22 ft, well under the 39.5 ft interior length.
The triangular truss is enclosed with rigid honeycomb-composite wall/roof panels and sealed acrylic windows. Floor panels lock into the truss nodes with gaskets.
Four rim-drive thrusters are used for the MVP instead of six, keeping redundancy (critical for station-keeping) while saving cost and container volume. Two are mounted low on the center leg; one each on the port and starboard legs. All are at 3 ft above the leg bottoms, sitting below the waterline when trimmed.
The MVP keeps a narrow 2-ft cantilevered deck across the aft transom. The dinghy is a 10-ft roll-up RIB with an electric outboard for the MVP; it stores deflated on the aft deck during transit and inflates for local errands. A simple two-point bridle and adjustable rode allow it to ride quietly in the wake, sheltered by the living platform on long moves. Full hard-davit integration is a Gen-2 upgrade.
| Feature | MVP — The Tern | Full Vision |
|---|---|---|
| Triangle size | 22' × 16' × 6.5'H | 70' × 35' × 7'H |
| Leg scale | 14' × 6' chord × 1.5' wide | 19' × 10' chord × 3' wide |
| Thrusters | 4× 12" rim-drive | 6× 18" rim-drive |
| Active stabilizers | 1 center + fixed winglets | 3× airplane-style active |
| Shipping | 1× 40-ft HC flatpack | On-site build / multiple containers |
| Dinghy integration | Towed / stowed RIB | Hard davits + 14' RIB recess |
| Target price (kit) | ~$75k–$95k USD | $350k+ |
| Key inclusions | Solar, fridge, watermaker, desk, queen berth | Full home, guest space, ocean crossing speed |
By treating the container as the master constraint, the MVP forces every subsystem to be modular and countable. A factory in Zhuhai or Ningbo can laminate the foil legs, cut the aluminum trusses, and pack the power station into one bill of lading. A small yard in Grenada or Panama can receive it, assemble it, and launch it without a custom mold or a mega-yard.
Most importantly, the Tern validates the core seasteading assumptions on a human scale: (1) SWATH comfort is real even on a budget, (2) solar-electric station keeping replaces fuel logistics, and (3) a containerized supply chain makes remote ocean living reproducible.