Build timeline and cost#

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

This document follows Sunwake from the design contract through launch, showing what is built and paid for at each stage. It includes two estimates because they serve different purposes. Costing A covers materials and systems, with owner labour, shed and overhead excluded; it is useful for deciding whether the design is financially viable. Costing B reflects the chosen build plan: a full-time owner, one paid professional boatbuilder, a rented shed, and an owner-installed 352 V system with professional engineering, staged sign-offs and commissioning. This is the amount that must be financed. Costing A is roughly $0.57–0.97M. Costing B centres on $1.00M, with a range of $0.80–1.25M. Section 8 explains the difference. Figures are in mid-2026 USD; dimensions are metric, with knots and nautical miles retained. The nominal schedule is 26 months from design contract to launch.

1. What each costing assumes#

The two estimates include different costs:

Costing A — owner labour free, no overhead.

• The owner's ~5,500 hours are valued at zero. So is the shed, the tooling, the transport, the crane, the survey and the insurance.
• The complete high-voltage and propulsion package is bought professionally installed and commissioned, as a single vendor line.
• Contingency is carried as an explicit 15–20 % line at the bottom rather than folded into each item.
• Replace each estimate with a quotation as it arrives. Keep the contingency line until every major item has been quoted.

Costing B — the crewed scenario.

• Crew: owner full time (unpaid, ~160 h/month) plus one skilled boatbuilder full time from shed-open to launch, $65/hr loaded ≈ $10.4k/month, employed ~23 months → ≈ $240k of wages. Combined throughput ~315 productive hours/month against a ~6,150 hour scope — the 5,500 hour owner scope of section 2 plus ~650 hours of electrical install moved out of the professional package and onto the owner.
• Shed: ≥ 17 × 9.5 m with 4 m clear, heatable, ~$3k/month including utilities, 25 months → $75k, plus $22k of fit-out and tooling.
• Electrics: the 352 V architecture of Electrical architecture and insurability, owner-installed but never owner-energised. The battery is bought as certified, professionally built sealed packs — the insurability study's condition at this voltage, and the reason the DIY-cells arithmetic is dead. Modules stay below 60 V until the integrator makes the final series connections. The owner runs cable, conduit, trays, solar, MPPT mounting and the entire 24 V low-voltage boat, all dead; the integrator inspects at stages and performs first energisation and commissioning. Priced at ≈ $280k all in, against costing A's $250–400k professionally installed line: the install labour saved roughly pays for the certified-pack premium and the oversight visits.
• Contingency: 15 % is included in every materials and hardware figure below, while wages, rent and fees are carried at their stated amounts. The running tally is intended as a working budget.
• Excluded from both: land and mooring, the owner's living costs, financing, and the value of the owner's own ~3,000 hours.

2. Effort#

The build scope, from Construction, scaled for Sunwake's panel areas:

A single owner working full time would need about 2.5–3 years. At 20 hours a week, the work would take 5–6 years, long enough for the finish on hull 1 to start ageing before hull 2 is faired. This is the main reason costing B includes a second pair of hands. The owner can do the work, but 950 hours of long-boarding creates a serious risk of delay or burnout.

Hulls can be built serially in a smaller bay and joined in rented space if 17 × 9.5 m is not available in one piece, but the join onwards needs the full envelope.

3. Costing A — materials and systems, owner labour free#

The professional high-voltage package is the largest single cost at 41–44 % of the boat. Compared with a low-voltage system, the 352 V architecture supports twin 20 kW DC generators, CCS charging, the ~15 kt sprint and the planned level of redundancy. See Generator selection and Electrical architecture and insurability.

Two levers sit inside the materials line. The Materials takeoff prices the bottom-up purchase plan — 250 sheets of plywood to order against a 310-sheet budget envelope, about 1,000 m² of glass including the tape inventory, 785 kg of epoxy, combined roughly $44–47k — and meranti instead of okoume saves a further $10–15k at about 15 % structure-weight cost, which the weight ledger will charge back at roughly 0.11 kt per 500 kg. The kit premium is separately examined in Cutting the kit, where owning the router instead of hiring one comes out close to a wash on cash and turns on schedule control.

4. Costing B — the crewed build, phase by phase#

Centre-case figures, each ±20 %. The running tally is cumulative spend, contingency included.

Phase 0 — Design, paperwork, mobilisation (months 1–4) · ≈ $116k · running $116k#

• Engineering first. The naval architect of record is contracted for the lines plan, the ISO 12215 scantling book, CFD checks, the HV one-line and the CNC kit files — scope, deliverables and staging per Naval architect engagement. About $46k of the ~$64k design line lands in this phase; the rest trails the build as site visits and trials support.
• Insurance before hardware. Send the broker question list now. Bind builder's risk and obtain the underwriter's written conditions — especially battery certification and the staged-survey cadence — before any high-voltage order is placed. Any condition that makes the project unworkable is best found at this stage. (~$7k including first-year builder's risk.)
• Mobilise. Shed leased and fitted out — racking, dust walls, heat, three-phase for tools. Long-boards and vacuum kit bought. Okoume versus meranti settled by quote. The CNC kit is ordered with a deposit alongside the bulk plywood, epoxy and glass buy (~$35k of deposits). The generator RFQ issues once.
• The boatbuilder is interviewed and signed this phase, and starts on kit day.

Phase 1 — Strongback, bulkheads, hull 1 (months 5–9) · ≈ $123k · running $239k#

• The kit arrives, the strongback goes down, and all bulkheads for both hulls are cut and glassed in one batch while the lofting checks run. Hull 1's panels are pulled to the bulkheads, stitched, taped both sides, sheathed and rolled upright.
• The photo build log starts at the first taped seam. Photograph every closure for the survey and insurance record. Start the weight ledger the same week: 500 kg costs about 0.11 kt at solar noon, so accurate weight tracking matters to performance.
• These are the learning-curve months: the pair runs slower than book rate while epoxy discipline, tape schedules and shop rhythm settle. Cash: wages $52k, rent $15k, kit and materials balances ~$48k, engineering trailing $8k.

Phase 2 — Hull 2 (months 9–11) · ≈ $41k · running $280k#

• The second hull should be about 30 % faster because the patterns and jigs are ready and the process is familiar. Both hulls are sheathed and rolled by month 11, providing a clear milestone within the first year and reducing the risk that the project stalls.
• These are the lowest-spend months of the build: wages $26k, rent and modest materials costs.

Phase 3 — Join, beams, bridgedeck, and the long-lead orders (months 11–14) · ≈ $141k · running $421k#

• Align the hulls on the wet-deck jig and join them, then install the plywood box beams and wet-deck panel. This is the most structurally sensitive geometry in the build, so the naval architect's site visit is scheduled here.
• Long-lead trigger. With the underwriter's terms in writing since Phase 0, place deposits of about 35 % on the certified 128 kWh packs, both 20 kW gensets, the drives, reduction and props, and the 15 kWp lightweight array. The roughly $90k of deposits should put delivery at the start of Phase 6. Ordering earlier adds storage costs; ordering later could stall the most expensive phase of the project.
• Cash: wages $26k, rent, join and beam materials ~$14k, deposits ~$90k.

Phase 4 — House, trunks, decks (months 14–16) · ≈ $46k · running $467k#

• Build the deckhouse, the trunk coachroofs over the hull queens, the decks and the aft-supported solar roof. The sprung sheer and arched-top lights in laminated frames give the boat its character without adding much cost in plywood, one of the reasons the Design brief chose this material.
• Glazing is ordered against finished openings and installed after paint. Cash: wages $21k, rent, materials plus the glazing order ~$18k.

Phase 5 — Fairing and paint (months 16–19) · ≈ $97k · running $564k#

• Allow about 950 hours of long-boarding to produce fair navy topsides. This demanding phase is a common source of delay on solo builds, so the schedule gives it three months and puts the professional in the lead.
• Epoxy barrier coat, two-part polyurethane navy topsides, cream house, gold cove and boot stripes. Paint before glazing, per the build sequence in Construction.
• Ship-systems early orders — heat pump, tanks, plumbing stock — land late in the phase so rough-in can start the moment paint cures. Cash: wages $31k, rent, paint system ~$14k, systems orders ~$44k.

Phase 6 — Systems and the owner-built 352 V install (months 19–23) · ≈ $292k · running $856k#

• This is the project's highest-spend phase. High-voltage balances fall due on delivery (~$167k), along with the remaining ship systems (~$63k), wages and oversight. Nearly a third of the budget is spent in four months.
• Owner scope, all of it dead: orange cable in glanded trays, service disconnects, tray installs, gensets set on double-elastic mounts, solar bonding and the MPPT wall, on-board chargers and isolation transformers, the entire 24 V low-voltage boat, plumbing and the heat-pump loop. The professional keeps carpentry moving in parallel and sets machinery.
• The owner-installed 352 V system follows three firm rules: packs arrive sealed and certified; nothing aboard exceeds 60 V until the integrator's visit; and first energisation is performed by the integrator, not the owner, hull by hull. Inspect the HVIL loop, insulation monitoring device and crash-stop wiring at each staged sign-off, and add the surveyor's photo checkpoints to the underwriter file as the work proceeds.
• Cash: wages $37k, rent $11k, hardware ~$230k, oversight visits $10k, second-year builder's risk $5k.

Phase 7 — Interior (months 21–24, overlapping) · ≈ $42k · running $898k#

• Modular furniture built off-boat and carried in: two queen berths over the battery trays, the saloon with its convertible dinette, the deck-level galley and the head with shower. White-painted panels, with varnished trim rationed to the weekend-a-year rule.
• Runs concurrent with late Phase 6 — one person on wires, one on wood. Cash: wages $21k, rent, interior materials ~$15k.

Phase 8 — Rig-out, launch, commissioning, trials (months 24–26) · ≈ $102k · running ≈ $1.00M#

• Install deck gear, rails, ground tackle, the folding mast, tender and platform gear (~$29k), then set the glazing. Weigh the boat against the ledger before it leaves the shed. The lightship design figure is 11,798 kg including the 6 % margin; the measured figure will close out the weight estimate.
• Transport and crane day (~$14k): at 7.29 m beam the boat moves as a wide load, and the permits are booked weeks ahead, not the week before.
• The integrator leads commissioning (~$14k). With energisation already complete, the work covers EMS dispatch logic, charge-source tests, sea trials against the acceptance list, genset noise checks and calibrated speed/power runs against the predicted curve.
• Complete the survey, stability assessment and inclining check, then convert builder's risk to an agreed-value policy. The photo log, staged sign-offs, conformity statements and commissioning report are assembled from month 5 onward so the insurer has a complete record at launch.
• Launch: month 26.

5. Where the money went#

Costing B, centre case, $k:

Planning band for costing B: lean ≈ $0.80M (meranti, lower-cost vendor selections, $55/hr, 22 months) · centre ≈ $1.00M · high ≈ $1.25M (high HV quotes, 30 months).

6. Reconciling the two costings#

The gap between $0.57–0.97M and $1.00M comes from the costs included in each estimate.

Costing A prices the boat's contents: design, materials, kit, systems, the high-voltage package and a contingency on all of it. It deliberately values the owner's ~5,500 hours at zero and ignores everything that exists only because the boat is being built somewhere — rent, heat, tooling, the crane, the surveyor, the insurance premiums, the wide-load permit.

Costing B prices the project. Onto the same contents it adds about $240k of professional wages and about $110k of shed, overhead and launch logistics, and it moves the high-voltage install from the vendor's scope to the owner's — buying certified sealed packs and staged professional oversight instead of turnkey installation, which is close to a net wash at ≈ $280k against costing A's $250–400k line.

Without wages and overhead, costing B comes to about $630k, comfortably inside costing A's band and slightly above its midpoint. The estimates therefore agree on the cost of the boat itself. For financing purposes, however, the paid labour and shed cannot be omitted.

Use costing A to compare Sunwake with alternatives or to check whether individual items have drifted. Use costing B for financing, because it reflects the chosen build plan and its full cash requirement.

7. Alternatives if high-voltage quotes are too high#

The 352 V architecture accounts for the largest line in costing A. If quotations make it unaffordable, either fallback can use the same hull, lines and build sequence.

48 V fallback. A low-voltage version with two roughly 11–13 kW gensets, two 12–15 kW drives, an owner-assembled battery and an electrician's sign-off in place of a high-voltage integrator would cost roughly $0.39–0.71M on costing A's basis. It would give up CCS, the sprint and about a knot of generator passage speed, leaving a conventional displacement cruiser with less reserve speed for weather. Evaluate this option in Phase 0 if the high-voltage quotes and the underwriter's conditions make 352 V impractical.

96 V packaged ecosystem — an alternative architecture under study. The ePropulsion I-40 / G102 route is a single-vendor, dealer-supported CAN system: two I-40 inboards, twelve G102-100 packs for about 123 kWh, vendor solar controllers and roughly $85–110k of core hardware, compared with $250–400k for the professional 352 V package. Its clear product history and dealer support may make it easier to insure as an owner installation. The compromises are substantial: the vendor's prohibition on third-party chargers rules out the twin DC generator architecture, and there is no established 96 V DC genset market, so passage-making would require AC gensets feeding approved chargers. CCS would also go, and the sprint would fall to about 12.5 kt. In return, the system could save $150–250k and greatly simplify integration. The dealer RFQ questions needed to assess it are listed in Open questions.

8. Schedule risks#

• Fairing burnout. Nine hundred and fifty hours of long-boarding puts both the schedule and the owner's morale at risk. The professional support and the uncompressed Phase 5 allowance are intended to manage it.
• High-voltage quotes discovered late. Run the broker question list and equipment RFQs in Phase 0, when the only sunk cost is design fees. A problem found in month 2 leaves time to change direction; the same problem in Phase 6 could put $250k of the project at risk.
• Delivery slip on packs or gensets stalling Phase 6. Mitigated by placing deposits at Phase 3 with delivery dates written into the purchase orders, and by keeping interior work (Phase 7) available as parallel schedule slack.
• Shed availability and the wide-load permit. Both are long-lead in their own way; the 7.29 m beam is not a phone call the week of launch.

The remaining risk is the owner's stamina. The 26-month schedule assumes a crewed build and consistent full-time participation from the owner for more than two years.

Cross-references: Design brief · Design specification · Construction · Materials takeoff · Generator selection · Electrical architecture and insurability · Cutting the kit · Naval architect engagement · Open questions