Minimal-Viable Seastead — Containerized Solar Catamaran
1. Executive Summary & Top Findings
- CriticalThe hull sections do not nest as described. Four identical 33-ft frustums nested "like cups" only insert ~1 ft per joint (limited by wall thickness ÷ taper slope), giving a ~129-ft stack — far beyond a 40-ft container. Three fixes are proposed in §3; the recommended one also improves the boat (shorter, wider hulls).
- AnswerBatteries: ~80 kWh LFP total ≈ 1,600 lb (720 kg); four banks of 20 kWh ≈ 400 lb (180 kg) each. Details in §5.
- AnswerPerformance: unlimited-range solar trawling at ~2.5 kn; full-battery sprints give ~27 nm at 5.5 kn (5 h) or ~44 nm at 4.4 kn (10 h). Table in §6.
- WatchStability drives the beam: with a heavy elevated pod you want ~8.5–9 ft... i.e., ~8.5–9 m overall beam, which happily lands the beams near your guessed 45–55°. Sketch calc in §4.
- VerdictBattery shipping is a solvable paperwork/carrier issue, not a blocker (§14). Budget a separate DG booking or regional sourcing, 2–3 weeks schedule buffer, $2–4k.
- MoneyEngineering & compliance one-time: $140k–245k. First-unit landed cost ≈ $320k (ex-engineering); at 20 units ≈ $205k. Suggested retail after batch 1: $289k–329k turnkey / $159k–179k kit (§9–§13).
- The water-assembly method you describe is sound and is the right call — it sidesteps the "cannot lift as a rigid boat" problem entirely (§11).
Contents
- Executive summary
- Baseline assumptions
- Critical check: hull-section stacking
- Weights, stability & part sizes
- Battery answer (weight & banks)
- Speed / range table (cases 1–5)
- Foam vs. air bags vs. sealed voids
- Naval-architect & compliance costs
- Manufacturing cost (China), 1/20/50/200 units
- Shipping China → St Maarten
- Assembly in St Maarten
- Total program cost
- Pricing & competitor comparison
- Shipping the LFP batteries (DG)
- Design commentary (your specific questions)
- Feedback on your validation plan
2. Baseline Assumptions Used Throughout
Where you left dimensions open ("naval architect will pick"), I assumed the following so numbers are traceable. Treat all as provisional.
| Parameter | Assumed value | Rationale |
|---|---|---|
| Solar array | 9–10 kWp | Cabin roof 12.2 × 2.44 m plus 3-ft wings each side ⇒ ~4.27 × 12 m usable; 24 × 450 W panels fit (6 rows × 4 cols landscape) |
| Daily harvest (Caribbean, derated 0.78) | ~40 kWh/day | 10 kWp × 5.5 sun-hours × 0.78; seasonal band 30–48 kWh |
| Battery | 80 kWh LFP (2 days) | Your spec; 90% usable = 72 kWh |
| Hull (recommended revision) | 2 sections × ~19.5 ft + cap; large end ~4.6 ft Ø | Chosen so nested pairs physically ship (see §3); LWL ≈ 38 ft |
| Hull wall | 5–6 mm (not 10 mm) | 10 mm is ~2× typical for this size; saves ~40% hull weight & cost. NA to confirm |
| Displacement (light ship + ½ stores) | ~10 t | Bottom-up estimate §4 |
| Design draft | ~0.55–0.65 m | From buoyancy calc, Ø1.4 m hulls |
| Overall beam | ~8.5–9 m | Driven by stability with elevated pod (§4) |
| Thrusters | 2 × 10 kW pods, large slow props | Matches sprint cases in §6; differential steering |
| Propulsion chain efficiency | 0.52 | battery/motor 0.9 × transmission 0.95 × prop 0.6 |
| Hull resistance model | Pwater(kn) ≈ 0.045·v³ kW | Calibrated to clean sailing-cat auxiliary data at 10 t; ±30% |
3. Critical Hull-Section Stacking Check
You asked specifically how long the 4 sections are when stacked like cups. Here is the math — and it changes the design.
3.1 Identical frustums barely nest
Two identical tapered shells can only telescope until the radial gap closes. The gap after inserting depth d is:
max depth d* = (wall + clearance) / taper_slope
For your stated 33-ft section (2 ft → 5 ft Ø): slope = 1.5/33 = 0.0455 ft/ft. With 10 mm wall + 5 mm clearance:
4-section stack = 4 × 33 − 3 × 1.1 ≈ 128.7 ft (39.2 m)
3.2 Fix options
| Option | Description | Containers | Verdict |
|---|---|---|---|
| A — Shorten sections (recommended) | Sections ~19.5 ft, large end ~4.6 ft Ø (hull LOA ≈ 41 ft incl. cap). Nested pair = 2×19.5 − 1 ≈ 38 ft ✓. Two pairs fit diagonally in one 40'HC: center-box check passes with ~15 cm margin (centers must be ≥1.44 m apart; available diagonal 1.60 m). | 2 × 40'HC total | Best Also improves the boat: LWL ~38 ft matches the cabin, easier handling, cheaper tooling |
| B — Keep 33-ft sections | Ship one section per container slot | 5+ containers | Reject kills the economics |
| C — Deliberate taper steps | Forward section sized to slide fully inside aft section; hull becomes stepped | 2–3 | Possible but hydrodynamically ugly and joints see bending steps; only if A fails |
4. Weights, Sizes & Stability
4.1 Part weights & container fit (Option A geometry)
| Part | Qty | Approx. size (each) | Unit wt | Lot wt | Fits? |
|---|---|---|---|---|---|
| Hull section (aluminum, 6 mm + framing) | 4 | Ø1.40 → Ø0.66 m × 5.9 m | 430 kg | 1.72 t | Nested pairs, hull-kit box ✓ |
| Pointy bow cap | 4 | Ø0.66 m → tip × ~2.2 m | 60 kg | 0.24 t | Nested ✓ |
| Joint flanges + watertight plates + fasteners | lot | — | — | 0.25 t | ✓ |
| Beams (aluminum box) | 4 | ~4.4 m × 0.25 m | 130 kg | 0.52 t | ✓ easy (<40 ft req. met) |
| Walkway + railings + ladders | lot | ~5 m × 1 m deck | — | 0.35 t | ✓ |
| Lateral fins / skegs | 4 | ~1.2 m² each | 45 kg | 0.18 t | ✓ |
| Solar panels 450 W | 24 | 2.0 × 1.0 × 0.04 m | 21 kg | 0.50 t | Stacked on edge ✓ |
| Mounting rails, wiring, MPPT ×3 | lot | — | — | 0.25 t | ✓ |
| Battery banks (see §5) | 4 | ~0.8 × 0.5 × 0.4 m | 180 kg | 0.72 t | DG — separate booking |
| Thruster pods + props | 2 | ~0.6 m pod | 60 kg | 0.15 t | ✓ |
| Inverter/charger, DC distribution, controls | lot | — | — | 0.10 t | ✓ |
| Water 400 L + waste 200 L tanks, pumps | lot | flexible tanks | — | 0.10 t | ✓ |
| Anchor 25 kg + 60 m chain + windlass | 1 | — | — | 0.30 t | ✓ |
| Assembly rigging (cables, turnbuckles, shackles) | lot | — | — | 0.15 t | ✓ (rent winches locally) |
| Living-pod outfit (glazing crated, galley, bed, head) | lot | inside pod | — | 0.60 t | ✓ |
| Total shipped (ex. batteries) | ~5.8 t | Payload limit ~28 t/box — fine | |||
4.2 Weight budget & buoyancy
| Group | Weight (t) |
|---|---|
| Hulls, caps, joints, skegs | 2.4 |
| Living pod (structure + outfit) | 4.5 |
| Beams, walkway, ladders, railings | 1.0 |
| Solar system | 0.75 |
| Batteries | 0.72 |
| Thrusters + electrical | 0.25 |
| Tanks, anchor, safety, rigging, spares | 0.85 |
| Light ship ≈ / loaded to ~10 t with crew, water, stores | ~10.6 |
Buoyancy: total hull volume ≈ 19–20 m³ (≈20 t) versus ~10 t displacement ⇒ ~100% reserve buoyancy, draft ≈ 0.6 m. Comfortable margin for the unsinkable-by-compartmentation strategy (§7).
4.3 Stability drives the beam — your 45° instinct is right
Rough transverse GM with a heavy pod centered ~2.2 m above WL: two circular waterplanes (r≈0.7 m) spaced S apart give waterplane inertia I ≈ 2·[π r⁴/4 + A·(S/2)²]. Requiring GM ≥ +0.3 m with KG ≈ 2.2 m needs I ≈ 19 m⁴ ⇒ hull centerline spacing ≈ 7.5–8 m ⇒ overall beam ≈ 8.5–9 m. Beam drop ≈ 3.6 m and horizontal reach ≈ 2.6 m gives a beam angle of ~50–55° and beam length ≈ 4.4 m — close to your 45° guess, and all beams still ship easily. Consequence: side-to docking is impractical — which matches the anchor-and-mooring target customer anyway.
5. Battery Answer (asked in your item 7)
Total installed weight: ≈ 9 kg/kWh pack-level ⇒ ~720 kg ≈ 1,600 lb (realistic range 1,450–1,750 lb depending on enclosure/BMS).
Per bank (4 banks): 20 kWh ⇒ ~180 kg ≈ 400 lb each.
Footprint per bank: ~0.8 × 0.5 m, ~0.4 m tall — fits the small end of a hull section behind a watertight sub-bulkhead with deck hatch, exactly as you propose. Cells ~160 Wh/kg; expect ~45 L of cells per bank.
Your instinct to put mass at the hull ends is good for seakindliness (adds pitch inertia), with one caveat in §15.4 about hobby-horsing. Cost: see §9 (≈$20–22k prototype, $13–16k at volume). Buy catalog marine LFP packs that already carry UN38.3 test summaries — a bespoke pack triggers $10–30k of testing (§14).
6. Speed & Range Table (your item 10)
Model: 10 t cat, 38-ft LWL, Pwater=0.045 v³ kW, chain efficiency 0.52, harvest 40 kWh/day, hotel load 6 kWh/day with A/C / 3.5 without. Treat speeds ±25–30% until tow tests exist. If you keep the original 66-ft hulls, add ~15% to speeds/distances.
| # | Scenario | Energy available | Avg power to water | Est. speed | Distance | End state |
|---|---|---|---|---|---|---|
| 1 | Typical sunny stretch, A/C on, 24/7 ops | 34 kWh/day | 0.74 kW | ~2.5 kn | ~60 nm/day | Indefinite (battery cycles daily ~50%) |
| 2 | Same, A/C off | 36.5 kWh/day | 0.79 kW | ~2.6 kn | ~63 nm/day | Indefinite |
| 3 | Batteries full (72 kWh usable), spend over 5 h, no sun | 72 kWh | 7.5 kW | ~5.5 kn | ~27 nm | Batteries empty |
| 4 | Same over 10 h, no sun | 72 kWh | 3.7 kW | ~4.4 kn | ~44 nm | Batteries empty |
| 5 | Full batteries, 10:00 cloudless, 4 h, A/C off, solar + pack | ~57 kWh (29 solar + 28 pack) | 7.4 kW | ~5.5 kn | ~22 nm | Arrive ~60% SoC |
7. Foam vs. Air Bags vs. Sealed Voids (your item 7 follow-up)
- Your compartmentation already does the job. Each hull section is an independent watertight box (joint plates + caps) ⇒ puncturing one section leaves ~75% of buoyancy. Add a high-water alarm + manual bilge pump per compartment and a laminated damage-control card. This is zero-weight safety.
- Pour foam: only ~100–130 kg to fill residual voids — cheap, but foam in aluminum hulls is notorious for trapping moisture against the alloy and hiding corrosion. Restrict it to the bow caps and stern peaks (impact zones) if anywhere.
- Air bags (I assume "air bangs" = air bags): fine as supplemental, removable flotation; they chafe, puncture, and shift, so don't make them primary. Valved inflatable bags lashed under the walkway are a reasonable option for peace of mind.
- Recommendation: sealed voids + alarms as primary; foam only in caps; bags optional customer choice.
8. Naval Architect & Compliance Costs (China-based firm, USD)
Typical rates $35–70/hr blended; Chinese firms usually quote lump-sum milestones. Timelines assume responsive client.
| # | Deliverable | Low | High | Duration | Notes |
|---|---|---|---|---|---|
| 1 | Feasibility / design review + build-cost estimate | $8k | $15k | 4–6 wks | Have them attack §3 nesting, §4 stability, joint fatigue first |
| 2 | Basic design: lines, GA, scantlings, weights, stability | $30k | $50k | 10–14 wks | To ISO 12215 / class-equivalent |
| 3 | Detailed production design: NC files, weld details, systems | $70k | $120k | 4–6 mo | The big-ticket item; includes jig design |
| 4 | Formal assembly-sequence engineering (incl. water-assembly rigging plan) | $8k | $15k | 3–4 wks | Can be folded into #3 for savings |
| 5 | Compliance package (itemized below) | $22k | $45k | parallel | |
| 6 | Quality control / inspection (per production batch) | $5k | $12k | per batch | See note below — yes, this exists and you should use it |
| 7 | Total one-time (items 1–5) | $138k | $245k | ~8–12 mo elapsed | Amortized: $10k/unit @20, $4k @50, $1k @200 |
8.1 Compliance package breakdown (item 5)
| Item | Low | High | Notes |
|---|---|---|---|
| Panama registry documentation (tonnage, particulars) | $2k | $4k | Plus ~$1.5–3k official/government fees paid directly; private yacht <24 m is straightforward |
| CSC safety-approval plate for custom container | $4k | $8k | Use certified ISO corner castings + third-party approval of the box to ISO 1496-1 principles; zero stacking rating is fine |
| Battery docs (UN38.3 summaries, MSDS, IMDG packing) | $1k | $2k | If catalog packs. A bespoke pack = $10–30k testing — avoid |
| Stability booklet + lightship check / inclining | $5k | $10k | Mostly from #2; inclining experiment extra |
| Electrical ISO 13297 / ABYC-style audit & docs | $5k | $10k | Insurers like this |
| Class-style structural dossier (optional) | $10k | $20k | Optional; helps resale/insurance |
8.2 Quality control — yes, this exists
- Third-party inspection firms (SGS, QIMA, V-Trap-style agencies): $300–600/inspector-day; typical 2–4 day pre-shipment inspection per batch.
- Witness points: material certs (5083/6061), weld visual + 10% dye-penetrant, dimension/nesting gauges, air-pressure test of every compartment (e.g., 0.15 bar soap test), load-test one beam+cable assembly to 1.5×SWL.
- Owner's engineer (your NA visiting) for the prototype: worth the flight money.
9. Manufacturing Cost — Parts Made in China (ex-works, USD/unit)
Aluminum fabrication commonly lands at $8–15/kg finished in Chinese yards; electronics at consumer-industrial pricing. Contingency not included here (added in §12).
| Line item | Proto ×1 | ×20 | ×50 | ×200 |
|---|---|---|---|---|
| Custom 40'HC aluminum living container (CSC corners, glazed, insulated, basic outfit) | 55,000 | 38,000 | 34,000 | 30,000 |
| Hull set: 4 sections + 4 caps + joints (~1.8 t aluminum) | 34,000 | 25,000 | 22,000 | 19,000 |
| Beams, walkway, ladders, railings, skegs (~1 t) | 16,000 | 11,000 | 10,000 | 9,000 |
| Solar 9–10 kWp: panels, rails, MPPT ×3, wiring | 6,000 | 4,500 | 4,200 | 3,800 |
| Batteries 80 kWh LFP + BMS (catalog packs) | 22,000 | 16,000 | 14,500 | 13,000 |
| Thrusters 2×10 kW + props + controls | 12,000 | 8,000 | 7,000 | 6,000 |
| Inverter/charger, DC distribution, monitoring | 3,000 | 2,000 | 1,800 | 1,600 |
| Plumbing, tanks (400 L fw / 200 L waste), pumps | 4,000 | 2,500 | 2,200 | 2,000 |
| Anchoring: 25 kg anchor, 60 m chain, windlass, bridle | 4,000 | 3,000 | 2,800 | 2,500 |
| Safety equipment (liferaft, vests, extinguishers, flares) | 3,000 | 2,200 | 2,000 | 1,800 |
| Assembly rigging: cables, turnbuckles, shackles | 2,000 | 1,500 | 1,400 | 1,200 |
| Spares & misc | 3,000 | 2,000 | 1,800 | 1,500 |
| Packaging, inland China transport, export docs | 6,000 | 4,000 | 3,500 | 3,000 |
| Total ex-works China | ~180,000 | ~120,000 | ~107,000 | ~94,000 |
10. Shipping China → St Maarten
| Element | Proto | Series (per unit) | Notes |
|---|---|---|---|
| Ocean freight, 2 × 40'HC | $9–12k | $8–11k | Via transshipment (Mediterranean or Miami); 5–8 weeks door-to-port |
| DG booking for batteries (Class 9) | $2–4k | $1.5–3k | Separate declared shipment or declared pallet section; see §14 |
| Marine insurance @1.5% | ~$3k | ~$2k | |
| Logistics subtotal | ~$14–18k | ~$11–15k |
11. Assembly in St Maarten (or similar Caribbean yard)
| Scenario | Duration | Labor + yard | Notes |
|---|---|---|---|
| Prototype | 6–9 weeks | $70–100k | Jig-making, learning curve, strain-gauge installs |
| Serial unit, yard does everything | 3–4 weeks | $45–70k | Crew of 3–4 @ $65–90/hr; travel-lift/crane $5–10k; consumables $3k |
| Serial unit, owner-assisted (your video/instruction model) | 3–5 weeks | $25–40k | Your water-assembly method shines here — see below |
Comments on your water-assembly sequence
- It's the right call: the tensioned-cable structure can't be lifted as a rigid boat, so building afloat avoids the problem entirely and cuts yard-space rental.
- Pre-bolt the two sections of each hull on land on a simple strongback (each section ~400–500 kg — needs a crane or gantry), air-test every compartment before mating, then launch hulls and float the pod between them.
- Specify the pretension procedure: load cells (even cheap dynamometers) on at least two cables, torque values + thread-locking on flange bolts, and a written sequence so different crews reproduce the same structural state.
- Needs a calm-window plan (leeward anchorage, <10 kt wind) and over-water work safety (harnesses, floats). Budget 2–3 "weather days."
- Final fit-out (batteries, panels, furniture) afloat is normal practice for small yards — fine.
12. Total Program Cost (China + shipping + St Maarten assembly)
| Stage | Prototype | Batch of 20 /unit | Batch of 50 /unit | Batch of 200 /unit |
|---|---|---|---|---|
| Parts ex-works China | 180k | 120k | 107k | 94k |
| Shipping + DG + insurance | 16k | 12k | 10k | 9k |
| St Maarten assembly (yard-complete) | 85k | 55k | 50k | 45k |
| Contingency / warranty reserve | 15% | 10% | 10% | 8% |
| Landed COGS per unit | ~320k | ~205k | ~183k | ~161k |
| + Amortized engineering/compliance | (separate) | +10k | +4k | +1k |
| All-in cost basis | — | ~215k | ~187k | ~162k |
To reach a proven prototype: ~$320k (hardware) + $140–245k (engineering/compliance) + model testing & trials ($30–60k) ⇒ roughly $490–625k all-in before revenue. Your deposit-crowdfunding idea (step 5) is a sensible bridge once the prototype has sea-trial data.
13. Pricing After the First 20 & Competitor Comparison
You hope volume lets you run thinner margins than yacht-industry norms — agreed, but don't underprice the first years: you need warranty reserves, field-support travel, and design-change money. Target 35–50% gross margin initially.
| Channel | Recommended price | Notes |
|---|---|---|
| Turnkey, assembled & in the water, Caribbean | $289k–329k | vs. ~$205–215k cost basis ⇒ healthy but disruptive margin |
| Kit, FOB St Maarten (containers + docs + video support + remote help) | $159k–179k | Customer adds local assembly $25–70k ⇒ all-in ~$200–250k; you hold less cash & liability, scale faster |
| Prototype / early-adopter units | $399k+ | Funds development; find founders who value influence over price |
13.1 Comparison — new yachts delivered to the Caribbean
| Vessel | Price delivered | Living area | Draft | Energy | Delivery pain |
|---|---|---|---|---|---|
| This seastead | $289–329k | ~30 m² + large decks | 0.6 m | Solar only, silent | Built regionally — none |
| Lagoon 42 (new) | $850k–1.05M | ~100 m² | 1.25 m | Diesel + sail | EU delivery $25–60k, 2–6 wks, wear & insurance |
| Fountaine Pajot Astrea 42 | ~$1.0M | ~95 m² | 1.15 m | Diesel + sail | Same |
| Leopard 46 (new) | $1.1–1.3M | ~110 m² | 1.4 m | Diesel + sail | Same (Cape Town/SA builds sometimes) |
| Silent-Yachts 55/60 (closest solar competitor) | €1.7–2.5M | ~100 m² | 1.0 m | Solar ~10–15 kWp | Austria build — worst-case delivery logistics |
| Used 2019 Lagoon 42 | $500–620k + survey/refit | ~100 m² | 1.25 m | Diesel + sail | Already regional, but condition lottery |
Positioning truth: you will not beat a Lagoon on space — you beat it on price per unit of autonomy: no diesel, no sails to learn, no marina bills, 0.6 m draft for gunkholing, apartment-stable platform, and a price point (~⅓ of a new 42-ft cat) that opens a market segment that literally doesn't exist today. Your niche logic (older couples, tech nomads, thrifty liveaboards) is coherent; the honest counterpoints to publish are: less interior volume, 5.5–7 kn top speed, 8.5–9 m beam limiting dockage, and unproven resale.
14. Can the LFP Batteries Ship Inside Our Custom Container?
- Lithium-ion batteries (UN 3480) or in equipment (UN 3481), Class 9, move in ISO containers every day under the IMDG Code with: DGD (declaration), UN38.3 test summaries, MSDS, packing to P903, terminal protection, Class 9 labels/markings.
- Carrier policy is the wildcard: some lines decline DG mixed with household goods in one box, and several impose state-of-charge limits (commonly ≤30–50%) for UN 3480. Book the batteries as their own DG container or as a clearly segregated, palletized, declared section, and confirm SoC policy at booking.
- Use catalog marine LFP packs whose UN38.3 certificates already exist; a custom pack means new testing ($10–30k, 2–4 months).
- Plan B (robust): source batteries regionally (Florida/Puerto Rico/USVI distributors) or ship them as a small separate DG shipment — LFP is commodity enough that this costs little extra.
- Panama flag registration doesn't care how the batteries arrived. Budget: 2–3 weeks schedule buffer, $2–4k incremental cost.
15. Design Commentary (point-by-point)
15.1 Concept & market
"Moveable home first, transportation second" is a genuinely distinct product category, and Starlink removes the last big objection to living at anchor. Targeting outside the hurricane belt in season keeps structural demands modest — but design the mooring gear for a named-storm escape plan anyway (customers will push their luck).
15.2 The container-as-cabin fit
The corner-fitting synergy you spotted is real: ISO corner castings are rated for ~86 t compression, ideal anchor points for cable pretension. Keep the castings permanently installed (needed for CSC anyway) and galvanically isolate stainless shackle hardware with isolator bushings/washers + sealant; the aluminum pod otherwise pairs safely with aluminum hulls/beams. Watch condensation: an aluminum box needs a proper thermal-break insulation layer and ventilation design, or owners will fight mold.
15.3 Beams & cables (the Wharram parallel)
Your Wharram observation is apt: a tension-compliant joint distributes loads and forgives misalignment. Engineering consequences: (a) beams become struts in compression — check buckling, not just bending; (b) flange bolts see cyclic loads — specify friction-grip bolting, Belleville washers, re-torque schedule; (c) cables need turnbuckle adjustment + optional load-cell telemetry; (d) design for one cable failed survivability explicitly in the FEED (your model-test item 3 — good).
15.4 Hobby-horsing & thrust modulation
Yes — with thrusters low and aft, differential/alternating thrust gives meaningful pitch damping authority at 2–5 kn; implement as a software mode. Counterpoint: putting all four battery banks at the extremes maximizes pitch inertia, which damps swell motion but can worsen short-chop hobby-horsing. If sea trials show it, relocate one bank per hull toward midships — the modular bank design makes that a 2-hour change.
15.5 Boards, steering, props
Fixed shallow skegs (0.3–0.4 m) on each hull kill three birds: lateral area for crosswind, prop protection, beaching tolerance. Retractable daggerboards add windward ability but cost/complexity a thrifty buyer won't pay for — offer as option. Differential-thrust steering is fine underway but weak when stationary in wind; either accept it (anchor lifestyle) or add a small retractable bow thruster as an option.
15.6 Regulatory flags worth knowing early
- French-side St Martin / Guadeloupe / Martinique are EU territory: commercially selling new recreational craft there nominally triggers the EU Recreational Craft Directive (CE). Private sales and use under a foreign flag live in grayer zones — get one legal consult before pricing into French islands.
- Import duties: assembling from parts may classify differently (and cheaper) than importing a completed yacht — engage a customs broker early; this can swing landed cost several percent.
- Charter use later would trigger passenger/crew requirements — out of scope now, but don't accidentally market it as charter-ready.
- Insurance: the ISO/ABYC-style documentation package (§8.1) is what gets a surveyor to say yes on a novel design.
16. Feedback on Your Validation Plan (steps 0–5)
- Step 0 (scale model): strongly endorse. Suggestions: do the container-fit/nesting study in CAD first (free, catches §3 immediately); print at 1:10 Froude scale; add a torsion twist test (hulls twisted relative to pod) and the one-cable-cut test you listed. Test mooring/snubbing loads too.
- Step 1 (NA loop): gate spending: pay for feasibility (#1) only after the CAD nesting fix is chosen. Ask bidders to critique §3–§4 of this document as their interview.
- Steps 2–3 (prototype + trials): your strain-gauge and energy-logging plans are right. Add: cable-tension monitoring over weeks (creep detection), galvanic potential logging, and a 48-hour "silent ship" test (no shore power, A/C at night) — that's the demo video that sells this product.
- Step 5 (deposit-funded batches): sensible; take deposits only after sea-trial data exists, escrow them, and pick batch size by deposits ÷ 0.4 (never fund more than ~40% of a batch from deposits).
17. Immediate Next Steps
- Decide the hull-length question (recommend Option A: ~19.5-ft sections, ~4.6-ft large end, 41-ft LOA) and re-run the CAD nesting study.
- Get 3 quotes from Chinese NA firms for item #1 (feasibility), sending them this document's §3–§4 as the challenge set.
- Parallel-track: Panama registration agent consult + customs-broker consult for Sint Maarten import classification.
- Shortlist catalog 20-kWh marine LFP packs with existing UN38.3 (this single choice de-risks §14 completely).
- Start the 1:10 model print + CAD fit study in-house while quotes come back.