```html
MVP Seastead Design
MVP Seastead Design — "SeaPod One"
This is a Minimum Viable Product scaled-down version of the full triangular trimaran seastead concept.
The guiding principle is: every structural and float component must fit inside a single 40 ft high-cube shipping container
so it can be manufactured in China and assembled at the destination (Caribbean first).
40 ft High-Cube Container interior: ~39.5 ft long × 7.7 ft wide × 8.8 ft tall.
This is the hard constraint that drives all the dimensions below.
1. Scaled Dimensions
The original 70 ft × 70 ft × 35 ft triangle is far too big to ship. We scale by ~0.5× and change the geometry slightly
so the three main parts of the hull can nest into a container.
| Feature | Original | MVP | Rationale |
|---|
| Triangle sides (L & R) | 70 ft | 36 ft | Fits container length in 2 bolt-together halves (2 × 18 ft) |
| Triangle back (width) | 35 ft | 20 ft | Ships as 2 × 10 ft sections |
| Frame height (floor–ceiling) | 7 ft | 6.5 ft | Still walk-around; saves weight |
| Floor area | ~1060 sq ft | ~300 sq ft | Studio-apartment size, enough for 2 |
| Float/leg length | 19 ft | 16 ft | Fits diagonally in container; 8 ft submerged, 8 ft above |
| Foil chord | 10 ft | 5 ft | NACA 0030 shape retained |
| Foil thickness (width) | 3 ft | 1.5 ft | Scales with chord |
| Thrusters | 6 × 1.5 ft RIM | 4 × 0.8 ft RIM | 2 on the rear floats only; cheaper, simpler |
| Stabilizer "airplanes" | 3 | 2 (rear floats) | Sufficient for pitch/roll damping at MVP scale |
| Dinghy | 14 ft RIB | 9 ft inflatable w/ small electric OB | Lighter, cheaper, also fits in container |
2. Buoyancy & Displacement Check
Each float (NACA 0030, 5 ft chord, 1.5 ft max thickness, 16 ft long, 8 ft submerged):
- Foil cross-section area ≈ 0.685 × chord × thickness ≈ 0.685 × 5 × 1.5 ≈ 5.1 sq ft
- Submerged volume per float ≈ 5.1 × 8 = ~41 cu ft (plus some from the sloped bottom)
- 3 floats × 41 = ~123 cu ft submerged
- Buoyancy in seawater: 123 × 64 lb/cu ft ≈ 7,870 lb at the 50%-submerged design line
Target all-up weight: ~5,500 lb (leaves ~2,300 lb reserve buoyancy — plenty for stores, water, people).
| System | Est. weight |
|---|
| 3 composite floats (foam-cored FRP) | 900 lb |
| Aluminum triangle truss + floor + roof | 1,400 lb |
| Wall panels, glass, insulation | 800 lb |
| Solar array (~3 kW) | 250 lb |
| LiFePO4 batteries (15 kWh) | 300 lb |
| Inverter, MPPT, wiring | 120 lb |
| 4 RIM thrusters + cables | 200 lb |
| Watermaker, pumps, plumbing | 150 lb |
| Fridge/freezer, galley, head | 250 lb |
| 2 stabilizer "airplanes" | 120 lb |
| Dinghy + motor + davits | 200 lb |
| Furniture, personal gear, food, water | 800 lb |
| Total | ~5,490 lb |
3. MVP Feature List
Power
- Solar: ~3 kW of flexible/rigid panels on the triangle roof (~300 sq ft available, easily fits 3 kW).
- Battery: 15 kWh LiFePO4, 48 V nominal.
- Inverter: 3 kW pure-sine, 48 V→120 VAC.
- DC loads: fridge, lights, pumps, thrusters all 48 V to minimize conversion losses.
Sleeping & Living (for 2)
- Queen berth forward (in the pointy end of the triangle).
- Convertible dinette aft (can sleep 2 guests).
- Small wet head with composting toilet + shower stall.
- Galley: induction hob (1 burner), 80 L fridge/freezer combo (DC), sink.
- Storage: under-berth + under-seat + 2 hanging lockers.
Water
- 30 gal fresh tank + 20 gal grey tank.
- Small DC watermaker (~5–8 gal/hr, ~300 W) — Spectra Ventura-class.
Stability (the key selling point)
- Small-waterplane trimaran geometry: only the thin foil cross-sections pierce the surface → tiny heave response to waves.
- 2 rear "airplane" stabilizers with actuated elevators provide passive/active pitch damping.
- Result: a measurably softer ride than comparable-displacement monohulls or catamarans, at least while at anchor or at low speed.
Propulsion
- 4 × 0.8 ft RIM-drive thrusters (one each side of the two rear floats).
- Design speed: 3–4 knots cruise, 6 knots burst. This is a slow, efficient passage-maker, not a sport boat.
- All-electric; solar-only range at 3 kt ≈ unlimited in sunny conditions; reserve 8–10 hrs motoring on battery alone.
4. Container Packing Plan
Everything must nest inside one 40 ft HC container (inside: 39.5 × 7.7 × 8.8 ft).
| Item | Shipped form |
|---|
| 3 floats (16 ft × 5 ft × 1.5 ft) | Each split lengthwise into 2 × 8 ft halves, stacked. Inner cavities hold small parts. |
| Triangle truss (3 sides × 36/36/20 ft) | Each side shipped as 2 bolt-together sections (max 18 ft). Flat-pack aluminum. |
| Floor + roof panels | Honeycomb composite, max 8 × 4 ft, stacked. |
| Wall / glass panels | Modular 4 ft wide panels in a crate. |
| Solar panels | Flexible/rigid, stacked flat. |
| Batteries, inverter, thrusters, watermaker, galley, head | Pre-palletized at rear of container. |
| Dinghy | Roll-up PVC inflatable + electric OB in a crate. |
| Stabilizers | Detached wings, ship flat. |
Assembly time target: 2 people + 1 crane/forklift, 5–7 days on a boat ramp or beach. Bolt-together, no welding required on site.
5. Simplifications vs. Full Concept
- Drop 1 of 3 stabilizers — 2 rear ones handle pitch; roll is already well-damped by the wide trimaran geometry.
- Drop 2 of 6 thrusters — 4 is enough for the smaller boat; differential thrust gives steering.
- Smaller dinghy — a 9 ft roll-up RIB keeps shipping simple.
- No "sport" lift foils on bottom of legs — keep the 5° sloped bottom (cheap geometry) but don't design for planing speeds.
- Single enclosed interior, no subdivided cabins beyond head + main cabin + forward berth nook.
6. Target Price & Market
| Item | Cost (USD, est.) |
|---|
| Float & structural kit (China-built, FOB) | $35k |
| Shipping to Caribbean | $6k |
| Solar + batteries + inverter | $12k |
| Thrusters + controls | $10k |
| Watermaker + plumbing | $4k |
| Galley + head + furniture | $6k |
| Dinghy + OB | $4k |
| Assembly labor + launch | $8k |
| Contingency/margin | $15k |
| Approx. turnkey price | ~$100k |
At this price point the MVP competes with a used 30–35 ft cruising catamaran but offers:
- Far better motion comfort (small waterplane area).
- All-electric, solar-sustained operation.
- Modern apartment-like interior with panoramic glass.
- Low maintenance (no diesel, no rig).
7. Development Roadmap
- Phase 0 — CAD + CFD (3 months): finalize float geometry, confirm drag and stability numbers, structural FEA on the triangle truss.
- Phase 1 — Scale tow-tank test (2 months): 1:6 model tested for motion in waves, drag vs. speed.
- Phase 2 — Prototype build (6 months): one full MVP unit built in a Chinese yard, shipped to test location (e.g. Puerto Rico or USVI).
- Phase 3 — Sea trials & certification (3 months): verify motion comfort, energy balance, safety.
- Phase 4 — First 10 customer units: refine manufacturing, build dealer/assembly partner in the Caribbean.
Open technical questions to resolve in Phase 0:
- Exact center-of-gravity placement — queen berth forward may need to move aft to balance the dinghy+motor weight at the stern.
- Wave-piercing behavior of NACA 0030 sections at the waterline — is 30% thickness enough to avoid slamming on short-period Caribbean chop?
- Thruster cavitation at shallow 0.8 ft diameter — may need to mount deeper on the float, or go to 1.0 ft.
- Solar shading from roof structure vs. flat-panel yield.
8. Summary
The MVP "SeaPod One" keeps the distinctive features of your full concept — a triangular trimaran on small-waterplane foils,
all-electric, solar-sustained, with stabilizer airplanes — but shrinks everything to fit one 40 ft container. It targets
2 occupants, ~$100k turnkey, and a motion comfort level no similarly priced yacht can match. It's a scalable platform:
once the MVP is validated, the full 70 ft version becomes the "SeaPod Pro" with no fundamental design changes, just bigger parts and more containers.
```