Vessel Operations — Operational Requirements for The Claw

A converted Aframax tanker operating as a mobile plasma processing vessel in the Great Pacific Garbage Patch (GPGP), ~1,000nm from Honolulu. This document covers the full operational picture: power, cycles, weather, crew, maintenance, safety, and annual costs.

1. Power Budget

Vessel Baseline

A standard Aframax tanker has:

• Main engine: 11-14 MW (single slow-speed diesel)
• Auxiliary generators: Typically 3x diesel generators, 1.5-2.5 MW each (4.5-7.5 MW total installed)
• Emergency generator: 500-750 kW

For The Claw, the main propulsion engine is retained for transit. The conversion adds plasma processing equipment, syngas engines, and collection gear. The auxiliary power plant is significantly upgraded or replaced.

Power Demand by Mode

Transit Mode (Honolulu <-> GPGP)

Fuel consumption in transit: ~45-55 tonnes/day of heavy fuel oil (HFO) or marine diesel oil (MDO) at 14-15 knots. At 1,000nm each way and ~15 knots, transit is ~67 hours (~3 days) each direction. Round trip burns ~270-330 tonnes of fuel.

Sources: Aframax specifications via Wikipedia, Wartsila tanker design data

Processing Mode (On Station, Full Operations)

Critical note: The energy loop math (detailed in energy-balance.md) suggests syngas from 5-10 TPD of plastic can generate 4-9 MWh/day net after powering the torch. At processing rates toward 10 TPD, syngas should cover most or all processing + hotel load. Below ~5 TPD, diesel backup is needed.

Sources: PyroGenesis PRRS specs via pyrogenesis.com, plasma energy balance via NETL, syngas energy output ~815-900 kWh/ton via Science Council for Global Initiatives

Station-Keeping

Two options:

The GPGP is within the North Pacific Subtropical Gyre where currents are slow (0.1-0.3 knots). Plastic accumulates precisely because the water is relatively calm. Drift mode is the correct choice — the vessel drifts with the same currents that concentrate the plastic, repositioning with main engine or bow thruster only when needed to move to higher-density areas.

DP2 (redundant dynamic positioning) would be required if the vessel were holding station near a fixed structure (pipeline, wellhead). For plastic collection in open water with no collision risk, DP is unnecessary cost and fuel burn.

Sources: DP system overview via Kongsberg Maritime, Seavium DP guidance-for-your-offshore-operation)

Hotel Load Only (Standby / Weather Hold)

This is the weather-hold or maintenance mode. One auxiliary diesel generator covers it comfortably.

Source: Offshore vessel hotel load data via ScienceDirect, Marine Insight

Emergency / Backup Power

Diesel backup sizing: Even if the syngas system fails completely, the vessel must be able to run hotel load on diesel (~500 kW) for up to 30 days, plus transit home (~3 days at full power). This means carrying approximately 400-500 tonnes of diesel fuel as operational reserve, plus enough for the return transit.

Total Installed Power Summary

2. Operating Cycle — The 28-Day Rotation

Cycle Breakdown

Realistic Processing Uptime

Of the ~20 days on station:

• Weather downtime: 2-4 days (sea state too high for collection; see Section 3). Processing MAY continue if feedstock buffer is loaded, but collection stops.
• Maintenance: 1-2 days for plasma torch electrode swaps and equipment inspections
• Net collection days: ~14-18 days
• Net processing days: ~16-20 days (processing can continue from buffer stock during collection downtime)

Feedstock buffer strategy: Maintain a 2-3 day buffer of shredded, dewatered plastic in storage hoppers. This allows the plasma reactor to continue operating during short weather holds when collection is paused. Buffer capacity needed: ~15-30 tonnes (2-3 days at 5-10 TPD).

Crew Changeover

The changeover happens in Honolulu. The incoming crew flies commercial to Honolulu and boards while the outgoing crew departs. This is a hot swap — the vessel does not shut down systems. Key officers overlap for 4-8 hours for handover briefings.

Industry standard for remote offshore: 28/28 (equal time on/off) is standard for drilling and remote FPSO operations. Some operations use 28/14 (28 on, 14 off) to reduce crew costs, but 28/28 is better for retention and fatigue management at this distance.

Source: Offshore rotation standards via WTS Energy, Worldwide Recruitment Solutions

Supply Vessel Schedule

A dedicated supply run is needed once per cycle (every 28 days), plus the vessel carries supplies during its own transit.

What must be delivered (cannot generate on board):

• Fresh food and provisions (frozen/dry stores for 28 days loaded in port; fresh provisions via supply vessel at ~day 14)
• Diesel fuel (if burn rate exceeds carried reserves)
• Plasma torch electrodes and consumables
• Medical supplies and pharmaceuticals
• Spare parts (pre-positioned based on maintenance schedule)
• Potable water chemicals (RO membrane treatment)
• PPE, cleaning supplies, operational consumables

What IS generated on board:

• Freshwater (RO desalination — 10-15 m3/day for crew of 25)
• Electricity (syngas + diesel)
• Vitrified slag (byproduct, inert — stored or dumped per permit)
• Metal ingots (from inorganic fraction — stored for port offload)

Maintenance Windows

During each 28-day cycle:

• Daily: Equipment inspections, greasing, filter checks (1-2 hours)
• Weekly: Comprehensive equipment inspection, fluid sampling (4-8 hours)
• Per cycle: Plasma torch electrode inspection/replacement (8-16 hours downtime)
• Per cycle: Collection equipment inspection, net/boom repair (4-8 hours)

During port calls:

• Stores loading (8-12 hours)
• Slag/metal offload (4-8 hours)
• Shore-side specialist maintenance if needed
• Crew medical checks

Bad Weather Protocol

Key principle: Collection is the weather-sensitive bottleneck. The plasma reactor, being internal, can operate in higher sea states than the collection equipment. The feedstock buffer bridges the gap.

3. Weather & Sea State — GPGP Conditions

Location

The GPGP is centered roughly at 25-35N, 135-155W, within the North Pacific Subtropical Gyre. This is the convergence zone of the North Pacific Current, the California Current, the North Equatorial Current, and the Kuroshio Extension.

Annual Wave Climate (Estimated from WAVEWATCH III Hindcast Data)

Note: These are estimates derived from North Pacific wave climate literature and NOAA WAVEWATCH III model outputs. The GPGP sits in the subtropical high, which is calmer than the storm track to the north (40N+) but still gets long-period swell from distant storms. Actual conditions vary year to year, especially with El Nino / La Nina cycles.

Sources: NOAA high seas forecast products, Copernicus satellite altimetry data, Colosi et al. 2021 — seasonal wave height cycles

Operational Season

There IS a season. The Ocean Cleanup pauses GPGP operations for winter (roughly November-March) because harsh winter conditions reduce collection efficiency and increase equipment damage risk.

Recommendation: Operate year-round but plan for reduced throughput in winter. Alternatively, use winter months for dry dock / major maintenance. The Ocean Cleanup returns to port for winter — a mobile processing vessel could do the same, scheduling the 5-year survey and major refits for November-February.

Sources: The Ocean Cleanup — System 002 seasonal operations, Ocean Cleanup — GPGP overview

Storm Frequency

The GPGP area (25-35N) is south of the main North Pacific storm track (which runs 40-50N). Direct hits from extratropical storms are rare in summer, more common in winter when the storm track dips south. Tropical cyclone (hurricane) risk exists June-November but the central Pacific rarely sees direct landfalls at this latitude.

Expected weather downtime: ~15-25% of on-station time annually (higher in winter, lower in summer).

Currents

Surface currents in the GPGP are typically 0.1-0.3 knots. This is the gyre's center — water moves slowly, which is why plastic accumulates. This is favorable for drift-mode station-keeping.

4. Crew & Logistics

Crew Composition

Total crew: 24-28 per rotation (two full crews needed for 28/28 rotation)

Key considerations:

• Plasma operators are specialized — they need PyroGenesis training. Cannot be filled from general maritime crew pool.
• 24-hour operations require 3-watch rotation for bridge, engine room, and plasma operations.
• No helicopter crew — helicopter is not based on board (see below).

Sources: Maritime salary guide 2026, Crewlinker offshore vessel jobs

Rotation Model

Recommended: 28/28 (28 days on, 28 days off)

This is industry standard for remote offshore operations (drilling rigs, FPSOs far from shore). The key reasons:

• Fatigue management: MLC 2006 and STCW mandate minimum rest hours. 28/28 prevents cumulative fatigue.
• Crew retention: At 1,000nm from port, morale matters. Equal time on/off is the industry norm for remote work.
• Total crew required: 2 full crews x 25 = 50 personnel on payroll (one crew on board, one crew on leave).
• Travel: Crew flies commercial to/from Honolulu. The vessel transits to port for changeover.

Some FPSO operations in West Africa use 28/14 for cost savings (28 on, 14 off), but this requires a larger crew pool and leads to higher turnover.

Source: WTS Energy — 28/28 rotation

Helicopter Logistics

1,000nm is beyond the range of ANY offshore helicopter.

At 1,000nm from Honolulu, helicopter crew transfer is not possible. Even the longest-range offshore helicopter (S-92) can only reach ~500nm, and that is one-way with no reserve fuel — operationally impossible.

Options for emergency medical evacuation: 1. USCG C-130 fixed-wing + rescue helicopter relay — USCG can deploy a C-130 from Barbers Point, HI to provide on-scene coordination and drop supplies. Rescue helicopter can be deployed from a USCG cutter if one is within range. 2. Vessel transit to meet helicopter — Steam toward Honolulu at 15 knots while helicopter flies out. Rendezvous at ~500nm from shore (~33 hours sailing + helicopter flight). 3. Medevac to passing vessel — Transfer patient to a faster vessel heading to port. 4. US Navy assets — Pearl Harbor is the closest major naval base. Navy can deploy long-range assets for life-threatening emergencies.

Cost: No helicopter operating budget needed for routine crew transfer (crew transfers happen in port). Emergency medevac would be a USCG operation (no direct cost, but insurance must cover it).

Sources: Fair Lifts — offshore helicopter guide

Supply Vessel Logistics

Frequency: Once per 28-day cycle (mid-cycle resupply of fresh provisions, mail, critical spares)

Supply vessel type: Platform Supply Vessel (PSV), ~60-80m, hired on spot or short-term charter from Honolulu.

Round trip for supply vessel: 1,000nm each way at 12 knots = ~83 hours each way = ~7 days round trip. This is expensive — the supply vessel is committed for a full week per delivery.

Alternative: Reduce supply runs by carrying more stores during the vessel's own port call at each crew change. If the vessel loads 28 days of everything in port, mid-cycle supply runs may be needed only for urgent/unplanned items (every other cycle instead of every cycle).

Medical Capability

At 1,000nm from the nearest hospital (Queen's Medical Center, Honolulu), the vessel is 24-48+ hours from shore medical care even at full speed.

Required medical capability (per STCW, MLC 2006, and flag state requirements):

The reality: At this distance, the medical strategy is stabilize and evacuate. Serious trauma, heart attack, stroke, or appendicitis requires getting the patient to shore ASAP. The vessel can steam toward Honolulu while coordinating USCG medevac.

Sources: STCW medical care requirements, MLC 2006 Regulation 4.1, MSOS offshore medical support

Communication Systems

Monthly satcom cost: $5,000-15,000 depending on bandwidth tier. Telemedicine requires reliable video capability.

5. Maintenance & Reliability

Plasma Torch Electrode Replacement

At 10 TPD, 24-hour operation: The reactor runs ~480 hours per cycle (20 days on station). Electrode replacement is needed at least once per cycle, possibly twice. Carry minimum 4 sets of electrodes per cycle.

Sources: PyroGenesis PRRS, Plasma torch electrode life data, PyroGenesis technical papers

Planned Maintenance Schedule

Critical Spares Inventory

Must carry on board at all times:

Dry Dock

Tanker vessels cannot apply for extended dry docking under current classification rules — The Claw must follow the standard schedule.

Sources: Marine Insight — dry dock cost estimation, ResearchGate — tanker dry docking cost modeling

At-Sea Repair Capability

The engineering team (Chief Engineer + 2nd + 3rd + ETO + 2 motormen) must be capable of:

• Plasma electrode replacement without shore support
• Diesel generator overhaul (top-end)
• Hydraulic system repair (collection equipment)
• Electrical fault-finding and motor replacement
• Welding and fabrication (dedicated workshop on board)
• Basic hull patching (above waterline)

What cannot be repaired at sea:

• Main engine crankshaft / bottom-end failure (tow to port)
• Propeller / shaft damage (tow to port)
• Major structural damage (emergency response)
• Reactor refractory rebuild (port-side maintenance)

6. Safety & Emergency

Emergency Response at 1,000nm

Reality check: At 1,000nm from shore, the vessel is largely on its own for the first 4-6 hours minimum. Self-sufficiency in firefighting, flooding, and medical emergencies is essential.

Firefighting for Plasma Operations

Plasma gasification involves:

• Temperatures exceeding 3,000C in the plasma arc
• Syngas (hydrogen + carbon monoxide — flammable and toxic)
• Molten slag at 1,400-1,600C

Syngas-specific hazards: CO is odorless and lethal. H2 is explosive in air at 4-75% concentration. Fixed gas detection with automatic ventilation and alarm is mandatory in all spaces where syngas is present.

Evacuation Procedures

Environmental Spill Response

MARPOL compliance: The vessel must meet MARPOL Annex I-VI requirements. Plasma processing emissions need to meet applicable air quality standards (MARPOL Annex VI, possibly EPA requirements given US flag/port).

Coast Guard / SAR Coordination

• File voyage plans with USCG before each transit
• Maintain AMVER (Automated Mutual-Assistance Vessel Rescue System) reporting
• Daily position reports via Inmarsat
• USCG District 14 duty officer contact maintained at all times
• Nearest USCG cutter position tracked (USCG publishes positions for SAR planning)

7. Annual Operating Cost Model (OPEX)

Assumptions

• 10-12 operating cycles per year (2-3 cycles lost to dry dock, major maintenance, or winter weather stand-down)
• 28/28 crew rotation, 2 full crews
• Honolulu as home port
• Vessel is owned (not chartered) — no charter/lease cost in OPEX
• All figures in USD, 2025 estimates

Crew Costs

Sources: Maritime Salary Guide 2026, Securewest salary guide

Fuel

Note: If syngas system achieves target reliability, on-station diesel backup drops significantly. First-year costs will be higher as the system is commissioned.

Consumables

Maintenance & Repair

Supply Vessel

This is one of the largest variable costs. Minimizing supply runs by maximizing stores at each port call is critical.

Insurance

Note: This is a novel vessel class performing a novel operation. Underwriters will price uncertainty. First-year premiums may be higher until loss history is established. Estimates based on general FPSO and tanker insurance data.

Sources: Lloyd's List — vessel insurance

Helicopter Operations

$0 for routine operations — crew transfer happens in port. No ship-based helicopter.

Emergency medevac is covered by USCG (no direct cost) and insurance.

Port Fees & Shore Support

TOTAL ANNUAL OPEX SUMMARY

Rounded Estimate: $12M - $21M per year

Central estimate: ~$15-16M/year assuming moderate supply vessel frequency, reasonable syngas reliability, and no major unplanned events.

Cost per Tonne of Plastic Processed

For context: The Ocean Cleanup's cost per tonne is not publicly disclosed but is estimated at $5,000-20,000/tonne for collection alone (no processing). The Claw's cost includes full plasma destruction.

Key Uncertainties & Risks

Data Sources & Confidence Key

• KNOWN: Published specifications, regulatory requirements, established industry data
• ESTIMATED: Derived from analogous operations (FPSO, offshore drilling, tanker operations) with reasonable adjustments
• SPECULATIVE: Novel aspects of this operation with no direct precedent — flagged explicitly

Most cost figures are ESTIMATED based on analogous offshore operations. The plasma-specific costs are the least certain, as shipboard plasma gasification at this scale has no operational precedent.

Last updated: 2026-03-04 Research compiled from public sources including PyroGenesis technical papers, NOAA oceanographic data, maritime industry publications, and offshore operations benchmarks.