Sources and references#

Sunwake SW-15 · SW-REF Rev 1 · August 2026

This document collects the external sources used in the design: standards, vendors and products, precedent boats and their designers, relevant media, and the methods behind the calculations. Links were live in August 2026. An [inferred] mark means the organization was named in the design work, but the link is its main website rather than a page cited in the research.

Prices, underwriting requirements and product lines change. Inclusion here is not an endorsement. Before purchasing, confirm each vendor figure against a quotation that states its date and validity period.

1. Standards and regulations#

Waterway constraints are physical and legal limits rather than standards, but they set the air-draft and draft budgets: the Erie Canal low route at 4.57 m, the downtown Chicago River at 5.27 m, and the Bahamas banks below about 0.95 m. Illinois Waterway gauges can change by about 0.6 m in a day, so confirm the current level with the lock rather than relying only on the chart.

2. Precedent boats and designers#

The direct precedent#

Electric Philosophy — a 12.7 m stitch-and-glue solar-electric catamaran designed and built by Sam Devlin in 2021, 11.8 t, 9.5 kWp, twin 20 kW drives, with more than 3,000 nautical miles of service, including Alaska. It provides a close precedent for the construction method, boat type and size, and its service record helps calibrate the powering work.

• Devlin Designing Boat Builders — the design process
• Devlin — the design process in depth
• Sam Devlin profile — Power & Motoryacht

The solar-electric reference fleet#

A register of solar-electric catamarans and comparable solar-primary boats, held against a single schema so Sunwake's energy and weight budgets can be checked against boats that already float. The living register is maintained in the project workspace as issue SUN-20 with one profile per boat (SUN-21 through SUN-28); this section is the published snapshot, taken 29 August 2026 and retained here at Pete's direction. The principal comparison is energy per nautical mile against displacement; the surrounding fields explain each boat's position on that curve.

Every figure carries one of four labels, and unknown is used instead of a guess:

• measured — logged or instrumented first-hand by the owner or operator
• builder-reported — stated by the builder, owner or seller; no logs seen
• press-reported — manufacturer figures repeated by media, not independently verified
• derived — Sunwake arithmetic from labeled figures. Unless noted, Wh/nm is derived as propulsion power ÷ speed at the quoted cruise point, using the midpoint where a range is published, and excludes house load

Helios 11 — Lukas Sjöman's owner-built plywood-and-glass solar boat, sailed more than 3,000 nm from Finland to Ibiza without fuel. The headline is weight: ~1.5 t at 11 m. The ~590 Wh/nm is derived from 3.5–4.0 kW at 6.0–6.7 kn (midpoints 3.75 kW ÷ 6.35 kn), reported during a run into a 20 kn-plus headwind. Daily range is builder-reported at ~100 nm standard, ~40 nm in rough water under cloud, and ~150 nm on a bright day with the auxiliary sail up — the 40 nm figure is the one a passage plan has to survive. The hull type is reported inconsistently (monohull, catamaran, or monohull with added outriggers) and is treated as unresolved. Daily Galaxy · Supercar Blondie · Autonoción · greenMe

Skoota 32/36 solar — a Richard Woods Skoota plywood power catamaran built as a solar boat in Peru and offered from Paraguay. Two published operating points on the same 6 kW ePropulsion outboards Berenik-E uses: 6.0 kn at 3–4 kW (~583 Wh/nm derived at the midpoint) and 3.7 kn at 1.25 kW (~338 Wh/nm derived) — a 38% speed cut buying a 42% drop in energy per mile. Displacement is unpublished, so the boat cannot yet be placed on the Wh/nm-versus-weight curve. solar-motor-katamaran.com · Woods Designs — power catamarans

Wetdream — a year-2000 Gemini 105M sailing catamaran converted to full solar-electric and documented by its owner on a forum. The 5.3 kn at 3.2 kW sweet spot is the owner's own logged figure (~604 Wh/nm derived). The ~4.5 t is the Gemini 105M light-ship book figure, not a measurement of the boat as converted. The Gemini's unusually narrow beam (4.3 m) limits how directly the resistance figures transfer. Build thread · Related 100% solar cat thread

Berenik-E — an 11 m × 6 m converted sailing catamaran, around 5 t, owned and converted by Reinhard Leitner; a public build post names a Richard Woods design as the base boat. The owner's site reports 5.53 kWp of bifacial solar (14 × 395 W), ~30 kWh of LiFePO₄ (two 16S strings at 280 Ah), two 6 kW ePropulsion outboards, a Victron MultiPlus 5 kVA inverter/charger, and approximately 1,500 nm covered in the August–September 2025 season. Publication note: the owner has additionally supplied a measured cruise operating point and daily energy figures in private correspondence. Permission to cite them was requested on 29 August 2026 and is not yet on record, so this section carries only what his public pages support; the cruise point, and the consumption figure derived from it, are held in the project workspace (SUN-21) and will be published here — labeled as derived from the owner's reported operating point, with the arithmetic shown — once permission is recorded. solarkat-berenike.at · Technology · Builder's post naming the Woods base design · MarineTraffic

SoelCat 12 — a production solar-electric excursion catamaran for 16 passengers. The 2.17 kWh/nm is the builder's own consumption figure; it cross-checks against the claimed 120 kWh ÷ 60 nm battery range at 2.0 kWh/nm. The speed it applies at is assumed to be the 8 kn of the range claim — not stated by the builder. Included as the commercial-workboat end of the range: roughly 3.6× the energy per mile of the owner-built cluster, on a hull only a meter longer, from passenger payload, an 8 kn design speed and 60 kW of installed propulsion. Soel Yachts · Cruising Odyssey · New Atlas

Silent 60 — the best-known production solar cruising catamaran, claiming up to 100 nm/day on solar "for weeks". No power-at-speed figure is published, so Wh/nm cannot be derived; displacement is unpublished. Press reports of 2 × 200 kW propulsion conflict with Silent's own published 60-series options and are treated as unconfirmed. Silent Group · Electrek · designboom

Solarwave 64 — Michael Köhler's solar catamaran, the direct predecessor of Silent-Yachts, claiming ~100 nm/day. No power-at-speed figure is published. It contributes the register's only builder-published battery mass: ~590 kg for 100 kWh, about 5.9 kg/kWh installed — a useful validity check for any weight ledger. New Atlas · designboom · Yachting Magazine

Tûranor PlanetSolar — the first solar-electric circumnavigation: 584 days, 32,401 nm, 2010–2012. At 5 kn it averaged 17 kW of propulsion plus ~3 kW of hotel load — ~3,400 Wh/nm propulsion, ~4,000 Wh/nm total (derived). At 85 t with an 11.7 t battery (13.8% of displacement) and 93 kWp over 512 m² (182 W/m² of array area, with 2010 cells), it bounds the heavy end of the curve. Wikipedia · Ship Technology · Knierim Yachtbau

What the fleet indicates#

All ratios in this subsection are Sunwake arithmetic (derived) from the labeled figures in the preceding table.

• Three independent boats converge on ~583–604 Wh/nm at 5–6.7 kn — Skoota, Helios 11 and Wetdream — across 1.5 t to 4.5 t and across plywood, plywood/glass and GRP construction. A convergence within about 4% is the most useful single fact in the register: if Sunwake's resistance model lands far outside that band at similar speed and weight, the model needs explaining before the fleet does.
• Displacement dominates. PlanetSolar at 85 t uses roughly 5.8× the energy per mile of Helios 11 at 1.5 t, while going slower. The weight budget is not a housekeeping concern; it is the design.
• Solar power per tonne forecasts the outcome cheaply. Helios 11 carries 4.0 kWp/t and claims ~100 nm/day. Berenik-E carries 1.11 kWp/t and PlanetSolar 1.09 kWp/t — and PlanetSolar needed a 512 m² purpose-built deck to get there.
• Array per meter of hull is the real deck constraint. The fleet spans 0.41 to 0.94 kWp/m of LOA. The high end belongs to an 18 m luxury platform with an uncluttered hardtop; the two 11 m boats achieve 0.50–0.55 kWp/m.
• Storage sizing is genuinely contested. Battery capacity runs from 3.4 h to 16.8 h of array-equivalent storage with no consensus; Köhler — the most experienced solar cruiser in the register — sized the Solarwave 64 at 6.7 h. Battery is weight, so this is a decision to make deliberately rather than by copying anyone.
• Published daily range is nearly useless without weather. Helios 11 is the only boat that publishes its bad day (~40 nm), and that is the figure a passage plan has to survive. Everyone else quotes their good day.
• The counterpoint stands. Richard Woods — Electric powered boats for ocean cruising — argues the concept does not close, because drag grows with the cube of length while deck area, and so array size, grows with the square. The light boats in the preceding fleet entries hit his 6 kn target on 3.5–4.0 kW rather than his 5 kW because they are lighter than the boat he had in mind. The scaling law holds; the escape is to stay light and accept 5–6 kn, not to dispute the physics.

These are comparison points, not Sunwake baseline inputs. No figure in this section feeds constants.py or any published Sunwake performance number. Whether any precedent transfers is a question for the resistance and energy models, which must reproduce both ends of the fleet's displacement span. Every figure here is published by a builder, an owner or the press unless labeled measured, and none has been independently verified by this project.

Conventional-power benchmarks#

Maine Cat of Bremen, Maine, built displacement power catamarans in Sunwake's size class. These conventional-fuel boats are not solar-electric analogues, and no figure in this section feeds a Sunwake baseline. The P-38 documents a public example of the hull-development work that Sunwake plans to commission. The P44 shows the displacement of a fully fitted conventional power cat with similar dimensions. The US Coast Guard manufacturer record lists Maine Cat as out of business as of January 2, 2023, so treat each figure as a historical record rather than a builder claim.

The P-38 → P-47 hull-development lineage (Oak Hill Marine Design). Oak Hill reports that Maine Cat's owner supplied preliminary sketches. Steve Hudson developed the 11.6 m (38 ft) displacement power-cat hull from those sketches. The work included a MultiSurf surface model, hydrostatics and hull coefficient checks at each pass, four major revisions of the lines, and two 1/10-scale models tow-tested on the Medomak River before approval. Oak Hill sent production geometry to the mold shop as IGES sections. The hull was built in winter 2006 and tested in April 2007. The supplied diesel-electric system did not reach the estimated full speed of 20 kn. The published account does not establish whether hull resistance or the propulsion package caused the shortfall, and the builder postponed repowering. From 2008, Oak Hill adapted the design into a 14.3 m (47 ft), 33-passenger US Coast Guard Subchapter T ferry. Oak Hill reports that the adaptation widened the hull beams by 0.3 m (1 ft) and had a lightship displacement of 9.5 t (21,000 lb). The ferry was commissioned in 2011 and delivered in 2012.

Sunwake draws two lessons from this record. These lessons are project interpretations, not statements from Oak Hill. First, the development sequence of sketches, a surface model, checked hydrostatics, scale tow tests, and production geometry matches Phases 1 through 3 of the naval architect engagement. Second, the propulsion shortfall shows why one party must own resistance verification and the propulsion interface. Two questions remain unresolved. The published account does not identify the cause of the P-38 shortfall. A ferry-variant lines drawing that Oak Hill supplied to the project lists 11.8 t (26,000 lb), while Oak Hill's page reports 9.5 t (21,000 lb). The project holds the drawing in the repository under Oak Hill's proprietary-rights notice. Workspace issue SUN-38 records the review.

• Oak Hill Marine Design — Maine Cat P-38
• Oak Hill — Maine Cat passenger ferry
• US Coast Guard manufacturer record for Maine Cat

**Maine Cat P44 *Acadia*** — a one-off or semi-custom P44 listed for sale in Rockland, Maine, in August 2026. Workspace issue SUN-37 profiles it as the heavy fitted conventional benchmark. The broker lists a 14.63 m (48 ft) LOA for the nominal 13.4 m (44 ft) model, a 5.18 m (17 ft) beam, a 0.91 m (3 ft) draft, an unspecified displacement condition of 16.33 t (36,000 lb), two 175 hp outboards, and 0.44 kWp of hardtop solar. A video claims a 10 kn cruise at about 1.9 L/nmi (2 nmi/US gal) but provides no logs. The listing and video are not survey measurements. Sunwake derives an array ratio of about 0.027 kWp/t, which makes the array a house-load supplement. This boat is a conventional power cat, not a solar-electric precedent, so it remains outside the solar-electric fleet table. It packages two walk-around cabins, two separate showers, laundry, 8.8 kW (30,000 BTU/h) of air conditioning, a generator, and a tender crane in dimensions similar to Sunwake. Its listed displacement of 16.33 t exceeds Sunwake's 12.70 t half-load estimate. Each comfort requires an explicit weight, energy, and cost decision. YachtWorld listing · Cruising World builder history

Amateur-build precedent in plywood#

• Dudley Dix (Dix Design) — Dix 430 (13.1 m), Dix 470, DH550 (16.8 m): radius-chine and sheet-plywood catamarans amateur-built worldwide, with a mature CNC kit pipeline. Dix 430 · plywood catamaran kits
• Richard Woods (Woods Designs) — the Skoota 28/32/36 plywood power catamarans, the closest existing owner-built power cat precedent, with a published shell takeoff. Power catamarans · Skoota introduction
• James Wharram Designs — Tiki and Pahi catamarans, plywood and epoxy, routinely amateur-built at and above this size. wharram.com

Candidate designers for the engagement#

See naval architect engagement for fit notes.

• Steve Hudson (Oak Hill Marine Design), Southwest Harbor, Maine — developed the Maine Cat P-38 power-cat hull and its 14.3 m (47 ft) Subchapter T ferry adaptation — Steve Hudson biography · Maine Cat P-38 · Maine Cat passenger ferry
• Kurt Hughes Multihull Designs, Seattle — multihulldesigns.com
• Bedard Yacht Design — solar-electric powercat design and plans — bedardyachtdesign.com
• Stephens Waring Design, Belfast, Maine — stephenswaring.com · their electric lake tender, in Maine Boats, Homes & Harbors
• Hylan & Brown, Brooklin, Maine — hylanandbrown.com/design · profile in Maine Boats, Homes & Harbors

Styling and systems reference#

• Silent Yachts — serial-hybrid architecture and the integral stern-platform styling device adopted into the lines plan.

3. Vendors and products#

Drives and propulsion#

• Danfoss Editron — the EM-PMI240-T180 PM machine and the EC-C1200-450 active front end; marine-class-approved power electronics, and the components behind the engineering-fallback generator build. Motor datasheet · AFE datasheet
• Cascadia Motion / Rinehart — candidate traction motor and inverter family. cascadiamotion.com [inferred]
• ePropulsion — I-series high-voltage inboards, and the I-40 / G102 packaged 96 V ecosystem carried as an alternative architecture. epropulsion.com [inferred]
• Torqeedo — Deep Blue and Deep Blue Hybrid, an established production example of a 348–352 V marine bus. Hybrid drives
• Sharrow / VEEM — toroidal propellers, evaluated as a deferred running change. The attraction is noise, not efficiency. sharrowmarine.com [inferred]
• Gates Poly Chain — the toothed-belt class specified for the 2.5:1 reduction. gates.com [inferred]
• Line cutters: Shaft Shark, Spurs, Shaft Razor class.

Generators#

• Fischer Panda — AGT 20-VS PMS, the primary recommendation, and the AGT 45-VS PMS that sits inside Torqeedo's Deep Blue Hybrid as a range extender. Hybrid-VS category · AGT 20-VS PMS · AGT 45-VS PMS · 2023 Hybrid Series brochure · PVMV-N custom-voltage program
• EPTechnologies — 12–20 kW Kubota-based DC generator, order-configurable from 48 to 800 V DC; the challenger, on weight. Generators · Product overview and the Sunreef 50 reference · METSTRADE listing

Ruled out, and why, in generator selection:

• WhisperPower — DC line tops out at 12 kW / 48 V
• Praxis Automation GreenGenerator — smallest is 140 kW
• Volvo Penta variable-speed sets — nothing below about 200 kW
• Yanmar YF12e — 48 V, 10.5 kW
• Genevos HPM-40 fuel cell — fits the bus window, quietest machine on the page, rejected on fuel logistics
• EODev REXH2 — hydrogen range extender, same reason
• Epic Power DC-DC modules — the stack-of-converters route to a 352 V bus, rejected

Batteries, BMS and power electronics#

• EVE — the prismatic LFP cell class used as the value baseline. evebattery.com [inferred]
• SVOLT and BYD — blade-format LFP cells, the packaging argument for putting a battery under a bed. svolt.cn [inferred]
• Orion BMS — US-made battery management in the EV-conversion class. orionbms.com [inferred]
• Lithionics — UL 1973-listed marine lithium products — UL 1973 for marine
• ROYPOW — DNV type approval announcement
• Victron Energy — MPPTs, inverter/chargers and the Cerbo GX class energy manager, including documented DC-generator support — generator auto start/stop
• Bender — insulation monitoring device class, one per hull. bender.de [inferred]

Structural materials and suppliers#

• Noah's Marine — BS 1088 Lloyd's-certified okoume in the sheet formats that matter: 1220 × 2500 · 1530 × 3050
• World Panel — marine plywood
• Meranti BS 1088 (Hydrotek class), Baltic birch and Douglas-fir marine plywood are specified by class rather than by brand — see materials takeoff §1.

CNC machines and cutting services#

• Avid CNC — PRO4896 (4 × 8) · PRO60120 (5 × 10) · PRO4896 review at MellowPine
• Sienci AltMill — sizes and prices
• Market context: 4 × 8 price tiers · used market · Surplus Record CNC routers
• Hewes & Company Marine Division, Blue Hill, Maine — an established kit-cutter for outside designers, an hour from a Downeast shed. Cutting for Vivier designs · Maine Built Boats profile
• Chesapeake Light Craft, Annapolis — custom CNC cutting at a published rate. Services
• 100kGarages — routing-rate norms. Cost estimating
• Professional BoatBuilder — CNC construction on the rise

Ship systems#

Specified by class rather than by brand, and listed here so the classes are findable: Kabola and Wallas for the HVO-fired hydronic backup heater; Spectra for the energy-recovery watermaker; TruDesign for composite through-hulls; Stat-X for aerosol fire suppression in the battery bays; Rocna and Spade for the primary anchor; Fortress FX-23 for the secondary; Garmin for chart plotters and digital switching; Starlink for satellite communications.

4. Insurance and underwriting#

The research behind electrical and insurability.

• Practical Boat Owner — "How I got insurance for my DIY eBoat" — the hard precedent: a 120 kWh DIY catamaran refused by multiple insurers over about two years before it was finally written
• PKYS — insurers and lithium installations
• Yachting Monthly — DIY lithium installation and coverage
• Marine Industry News — insurance refusals on lithium-ion boats
• Panbo — 2025 ABYC battery and electrical standard updates
• Small Craft Advisor — reader poll on wooden and home-built boat insurance
• Waterway Guide — the BoatUS fire-claims breakdown — 26% of boat fires from off-boat sources, about 47% from ordinary AC/DC wiring and engine-electrical faults, and 8% from batteries
• Yacht Sales International — electric boat company failures — background for assessing the risk of relying on a single vendor

5. Design process, fees and commissioning#

• Eric Sponberg — How to Commission a Yacht Design and Have It Built (PDF) — the fee-percentage bands
• Kasten Marine — Yacht Design Costs — the hourly-against-commission argument
• Caribbean Compass — conversion costs, part five — real-world DIY electric-conversion parts cost
• Practical Boat Owner — converting a catamaran to solar power

6. Video and media#

Four long-form build videos from a couple of physicists building a 68 ft custom solar-electric catamaran in Rayong, Thailand informed the systems thinking on this project — particularly on battery packaging, digital switching, and the serial against parallel hybrid question. Transcripts are not carried in this repository; the episodes are:

• "Inside Our Custom 68ft Solar Electric Catamaran — Full Tour" — interior and exterior, the bifacial solar roof and wing, a galley redesigned in Fusion 360, and the hull extension for the drivetrain
• "Our Electric Boat Runs on This Battery. Not Solid-State. Here's Why" — a 700 V, 254 kWh blade-cell LFP pack, cell spacing, and the argument against semi-solid-state, with an Orion BMS 2 in primary/secondary configuration
• "The System Behind Our New Solar Electric Yacht" — digital switching and propulsion control, and a clear treatment of serial against parallel hybrid architecture
• "The Unexpected Twist on Our Boat Build: Custom Wavebreaker Install" — the wave-breaker and nacelle install, and the battery module build

The design draws two points from this material: the thermal case for placing blade-cell packs low under the berths, and the need to plan digital switching as one system instead of adding relays piecemeal.

7. Methods, papers and computational tools#

The calculation package implements these methods directly instead of calling a library, so the references describe the methods rather than the software.

Software used or specified downstream: Rhino (.3dm) and STEP as the editable CAD deliverable formats; layered DXF for cut files; VCarve Pro as the CAM standard in the kit world; NumPy, SciPy and Matplotlib in the calculation package itself.

If a link is no longer available, the document that cites it still records the design decision and reasoning. Confirm any source that will be used to place an order or make a contractual decision.