⚓ Naval architect contracts
for your seastead trimaran
🌊 80′×40′ solar aluminum · active stabilizers · TLP-ready
37,000 lb estimated
You’re not just designing a boat — you’re engineering a floating home with
vertical-float trimaran geometry, soft-ride dynamics, and tension-leg adaptability.
A naval architect (NA) becomes your co-pilot through design, testing, and build support.
Here’s how contracts, royalties, rates, and timelines typically work.
📋 Typical contract types what you’ll sign
📐 1. Preliminary design & feasibility
Fixed fee or hourly. Delivers general arrangement, weight estimate, hydrostatics, and a stability letter. Often used to validate your AI + model tests before full engineering.
⚙️ 2. Full engineering package
Detailed structural, systems, aluminum welding specs, class/ISO compliance. Usually lump sum with milestones (concept, detailed design, final plans).
🛟 3. Build support & supervision
Hourly or retainer. Naval architect visits yard, reviews first article, answers RFIs. Critical for aluminum construction and active stabilizer integration.
📄 4. IP & production license
Defines who owns the design. For a series of 100 seasteads, a per-unit royalty or one-time buyout is standard. See details below.
📦 Building 100 copies? Royalties & license fees
✅ Yes, if you build multiple units from the same design, the naval architect typically receives additional compensation.
This reflects the ongoing value of the intellectual property.
$1,200–$3,500
per unit (fixed fee alt.)
2–3× design fee
full buyout option
Common models for a 100-unit seastead series:
- Per-unit royalty: 1.5%–3% of construction cost (or a negotiated flat $1,500–$3,000 per hull). Aluminum trimarans in this size often fall in the $2,000–$3,500/unit range for a production run.
- Sliding scale: 3% for first 10, 2% for next 40, 1.5% thereafter — incentivizes both sides.
- Design buyout: Pay 2×–3× the original design fee to own the plans outright. No further royalties. Recommended if you eventually sell seasteads to others.
- Hybrid: Reduced upfront design fee + higher per-unit royalty (common with startups).
⚡ Your leverage: Because you're bringing scale-model test data and simulation validation,
the architect’s risk is lower — you may negotiate toward the lower end of royalty ranges or a capped buyout.
💰 2026 rate expectations & design timeline
⏳ How long does it take?
- Concept & feasibility: 4–8 weeks
- Full structural & systems design (aluminum trimaran 80ft): 12–22 weeks
- Production-ready package (with TLP anchors, stabilizers): +4–6 weeks
- Typical total: 4.5–7 months for a complete build-ready set
Your existing AI studies + model tests can compress early phases significantly.
💵 Hourly / project rates
- Senior naval architect / PE: $145–$225/hr
- Mid-level designer: $95–$140/hr
- Full design package (80′ aluminum tri): $65,000–$145,000 lump sum
- Build support retainer: $3,500–$7,000/month
Rates vary by region (US/Europe higher, but seastead-agnostic expertise is niche).
🛠️ Do they help during manufacturing?
Absolutely — and you want this written into the contract. An aluminum trimaran with active stabilizers and tension-leg hardpoints demands precision.
- 🔹 Yard liaison: Reviewing weld procedures, aluminum grade substitutions, frame alignment.
- 🔹 First-article inspection: Naval architect typically visits when hull #1 is framed and again at launch.
- 🔹 Change orders: They evaluate structural impact if you adjust solar layout or payload.
- 🔹 Commissioning: Stabilizer calibration, inclination test, and trim verification.
Many contracts include 40–80 hours of “build support” in the base fee, then hourly thereafter.
⚖️ What to watch for in the contract
©️ Ownership of plans
You typically receive a license to build, not the copyright. If you want to modify or sell plans later, negotiate joint ownership or a buyout clause.
🛡️ Limitation of liability
Standard: architect’s liability capped at design fee. Since you’re testing models and doing simulations, you can mutually refine assumptions.
🌐 Jurisdiction
Anguilla-based project? Choose a neutral governing law (UK/US common law) to avoid complexity. Many marine contracts use English law.
🧪 Testing & simulation data
Contract should acknowledge your scale-model data and AI simulations as shared reference — reduces rework and strengthens design baseline.
🔗 Tension-leg structure integration
Because your trimaran may serve as a TLP platform, the naval architect must design
reinforced hardpoints, tendon attachment structure, and load paths for vertical mooring forces.
This is a specialized structural task — ensure the contract explicitly covers “TLP compatibility and mooring foundation design”
as a separate deliverable or clearly scoped inclusion.
🧭 General advice for first-time builders
- 🔸 Start with a paid feasibility study ($6k–$14k) before committing to full engineering. It aligns expectations.
- 🔸 Share your AI simulation links and model test videos early. It demonstrates technical seriousness and saves billable hours.
- 🔸 Aluminum expertise matters. Choose a naval architect with documented aluminum yacht or workboat experience — not just FRP.
- 🔸 Stabilizer integration is cross-disciplinary. The NA will coordinate with the active stabilizer vendor (gyro or fin). Budget for that interface engineering.
- 🔸 Class / certification: Decide if you need ISO 12215, ABS, or DNV compliance. It affects engineering cost significantly.
- 🔸 Payment schedule: Typical: 15% at signing, 25% at preliminary design, 35% at detailed design, 25% upon delivery of final plans.
- 🔸 Visit the architect’s office or meet via video with screen sharing — review the 3D model together before freezing geometry.
🌐 Seastead.ai · naval architecture contracting guide
v1.0 · tailored for 80′×40′ aluminum trimaran · 2026 estimates
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