Summary
Your project sits between categories: it is small (45 ft) but technically novel (semi-SWATH, foil-section struts, tension-leg mooring, differential electric propulsion, planned volume production). China's largest design institutes are geared toward large commercial ships and may decline or deprioritize a project this size. The most realistic paths are (a) a design-build yard with in-house engineering for a craft this size, or (b) a two-track approach: a research institute for hydrodynamic model testing plus a yard for production engineering. Total engineering budget for a first-of-kind design like this will likely land between US$150k–$350k and 12–18 months to a production-ready design, regardless of which firm you choose.
Candidate Firms
1. MARIC — Marine Design & Research Institute of China (CSIC 708 Research Institute)
About: MARIC designs the full spectrum of vessels — merchant ships, offshore engineering structures, naval auxiliaries, and high-performance/special-hull-form craft. They have real experience with unconventional hull forms and would have no difficulty with the naval architecture and systems integration of your seastead. They can also arrange model testing through partner institutes.
Concerns: As a large state institute, their billing structure and minimum engagement levels are set up for commercial ship programs. A single 45-ft one-off may be a low priority unless you frame it as a volume-production program (which you intend). Expect bureaucracy and slower iteration cycles than a small yard.
2. CSSRC — China Ship Scientific Research Center (702 Research Institute)
About: CSSRC operates China's major towing tanks and wave basins and designed the crewed deep-sea submersibles Jiaolong, Shenhai Yongshi, and Fendouzhe. They are arguably the single best organization in China for your hardest technical question: the seakeeping, drag, and damping behavior of your foil-leg semi-SWATH, including the effect of the heave plates.
How to use them: Realistically they are a testing and hydrodynamics partner, not a full production-design house. The strongest overall strategy is CSSRC for model testing and hull-form optimization, paired with a design-build yard for structure and detail design.
3. Heysea Yachts (Haixing)
About: Heysea builds production GRP and aluminum yachts roughly from 40 ft upward, including for export. They have in-house design/engineering, experience with volume production of glass-reinforced-plastic hulls (your foil legs would be very well suited to FRP molding for volume manufacturing), and they already ship boats internationally.
Concerns: Their in-house team is geared toward conventional yachts. A semi-SWATH with tension-leg mooring is outside their normal envelope, so expect them to subcontract or partner for the hydrodynamics, and budget for independent review.
4. Sunbird Yacht / Sunbird Boat Manufacturing
About: Sunbird has extensive experience with welded aluminum vessels in your size range — patrol boats, workboats, and small passenger/electric ferries. If you build the legs and triangle frame in aluminum (which suits containerized bolt-together construction), a yard like this is a strong match for both engineering and volume production.
Concerns: Same as Heysea — the novel hull form requires external hydrodynamic support. Their strength is structure, welding, systems integration, and repeat production.
5. Yunzhou Tech / OceanAlpha
About: Yunzhou (brand name OceanAlpha internationally) designs and builds small-to-medium autonomous electric surface craft, including some large USVs. They are among the best in China at exactly the subsystems that differentiate your project: electric thrusters, battery systems, differential-thrust maneuvering control, and station-keeping logic — including the two-vessel coordinated control for the connected-walkway scenario.
Concerns: They are primarily a product company, not a contract design firm. Whether they would take on contract engineering is unknown — this may evolve into a partnership or technology-licensing discussion rather than a design contract.
6. SDARI — Shanghai Merchant Ship Design & Research Institute
About: SDARI is one of the world's most productive ship design firms for container ships, bulk carriers, and tankers. They are highly capable but firmly oriented toward large commercial tonnage. Include them on your contact list for completeness, but expect that a 45-ft craft is below their normal scope; they may decline or route you to a subsidiary.
Comparison Table
| Firm | City | Best role on this project | Est. cost (USD) | Est. timeline |
|---|---|---|---|---|
| MARIC (708) | Shanghai | Full design cycle, if they accept a small novel craft | $150k–$300k | 10–14 mo |
| CSSRC (702) | Wuxi | Hydrodynamics: model testing of foil legs, seakeeping, heave plates | $40k–$90k | 3–6 mo |
| Heysea Yachts | Zhongshan | Design-build, FRP hulls, volume production, export experience | $50k–$120k | 4–7 mo design |
| Sunbird | Hunan | Design-build, welded aluminum, workboat-class construction | $50k–$120k | 5–8 mo design |
| Yunzhou / OceanAlpha | Zhuhai | Electric propulsion, autonomy, differential-thrust control, station-keeping | $40k–$100k (if contracted) | 6–10 mo |
| SDARI | Shanghai | Full design cycle — likely below their normal project size | $120k–$250k | 10–14 mo |
Recommended Strategy
- Two-track approach (recommended): CSSRC model-tests the foil-leg hull form (drag, seakeeping, heave-plate damping) while a design-build yard (Heysea or Sunbird) does structure and production engineering in parallel. Total: roughly US$150k–$250k, 12–16 months to production-ready design and first prototype.
- Design-build single contract: Fastest and cheapest route, with the yard subcontracting hydrodynamics. Total: roughly US$120k–$220k, 10–14 months.
- Engage China Classification Society (CCS) early. Your seastead is a hybrid between a vessel and an offshore structure, and its regulatory treatment (and whether you can register/insure it) may influence the design. CCS plan-approval typically adds 2–4 months and US$15k–$45k. CCS's rules research arm (Wuhan Rules Research Institute) can advise on which rules apply.
What Will Drive Cost and Schedule
- Model testing is not optional for a first-of-kind semi-SWATH. Your heave-plate sizing and the 50% submerged foil behavior need tank validation.
- Structural FEA of the triangle deck, walkway attachments, and leg-to-hull joints (the containerized bolt-together joints especially — they carry the entire load path).
- Regulatory ambiguity: classification societies have limited precedent for seasteads; expect extra review cycles.
- Prototype iteration: budget for at least one design revision after sea trials — this is the largest schedule risk.
- Production engineering (molds/jigs for volume manufacturing) is typically separate from first-unit design.
Non-Chinese Alternatives Worth Benchmarking
Because your concept is closer to small-craft multihull/seastead work than to ship design, you may get better value benchmarking quotes against specialists such as LOMOcean (New Zealand, designed the Adastra trimaran), Kurt Hughes (USA, multihulls and panelized/seastead-like designs), Vripack (Netherlands), or Shuttleworth Design (multihull specialists). Even if you build in China, a Western small-craft designer with a Chinese builder is a common and often cost-effective structure.