Sourced figures on what a medical diversion costs offshore wind operators — helicopter rates, vessel day rates — and how many evacuations are avoidable.
A medical diversion is an unplanned change to a vessel's or project's operations to move an ill or injured crew member ashore for treatment. In offshore wind, that usually means a crew transfer vessel (CTV) or service operation vessel (SOV) breaking off its work programme, an installation vessel suspending lifts, or a search-and-rescue (SAR) helicopter being tasked to the site.
Every operator accepts that some diversions are unavoidable — a suspected cardiac event or a serious crush injury leaves no room for debate. The commercial question is different: what does each diversion actually cost, and how many are triggered by conditions that could have been assessed and managed on site? The figures below are drawn from published industry and government sources.
Published government rates put a medium SAR helicopter of the type used offshore at roughly US$15,000 per flight hour. The US Coast Guard's reimbursable standard rates (2015) list the H-60 — the same airframe family used for offshore SAR in many countries — at US$14,979 per flight hour, and operating costs have only risen since that rate was set.
A round trip to a wind farm 40–60 km offshore, with time on scene for a hi-line or deck transfer, quickly becomes a multi-hour mission. In much of Europe the helicopter itself is state-funded, so the operator never sees that invoice — but the operational bill still lands on the project: work stops across the affected area, the casualty's team is stood down, vessels reposition to support the transfer, and the incident triggers reporting and investigation obligations. Every tasking also draws on a finite national SAR resource.
Charter day rates frame the exposure: around £2,000 per day for a CTV and around £30,000 per day for an SOV, both excluding fuel, according to the Guide to a Floating Offshore Wind Farm published by BVG Associates with ORE Catapult and The Crown Estate. During construction the stakes are an order of magnitude higher — Clarksons Securities modelled wind turbine installation vessel (WTIV) day rates at US$225,000 for 2023–24, with contracts around US$300,000 per day reported for 2025 (Riviera Maritime Media, 2023).
The day rate is only the visible part. A diversion in the middle of an installation campaign can forfeit a weather window that took days to open, idle a full technician crew and cascade into contractual delay. In merchant shipping, where these costs have been studied at scale, a 2013 International Maritime Health Association (IMHA) study covering 23,299 vessels put the average all-in cost of a medical diversion at US$180,000 — a figure that includes deviation fuel, port costs, delay and crew replacement, not just the charter.
Published estimates range from roughly 20% to as much as 30–50% of planned evacuations. The IMHA's 2013 study concluded that telemedical support could reduce unnecessary ship diversions by around 20%, worth an estimated US$168 million per year to the shipping industry. More recently, Ideagen (2026) cites industry data indicating that 30–50% of planned evacuations can be avoided through telemedicine consultation — either because the condition can be safely managed on board, or because the timing and destination of the evacuation can be optimised.
Two caveats. These figures come from merchant shipping and cruise operations, not offshore wind specifically — wind farms sit closer to shore, with shorter transits and different crew profiles, so the transferable number is directional rather than precise. And 'avoidable' never means 'ignored': it means a clinician assessed the case and confirmed it could be managed in place, with a documented plan for re-assessment and escalation.
Even at the conservative end, the arithmetic is meaningful. Ideagen (2026) estimates that for a mid-sized fleet, preventing just three evacuations a year is worth US$450,000–900,000 once diversion costs, schedule disruption and crew replacement are counted.
The table below assembles the published figures. They come from different sectors, years and currencies, so treat them as reference points for building a project-specific estimate rather than a single formula.
| Cost item | Indicative figure | Source |
|---|---|---|
| SAR helicopter (H-60 class), per flight hour | ~US$15,000 | US Coast Guard reimbursable standard rates, 2015 |
| CTV charter day rate (excl. fuel) | ~£2,000/day | BVG Associates / ORE Catapult guide |
| SOV charter day rate (excl. fuel) | ~£30,000/day | BVG Associates / ORE Catapult guide |
| Installation vessel (WTIV) day rate | US$225,000–300,000/day | Clarksons Securities via Riviera, 2023 |
| Average medical diversion, merchant shipping (all-in) | ~US$180,000 | IMHA study, 2013 |
| Share of planned evacuations avoidable with telemedicine | 20–50% | IMHA, 2013; Ideagen, 2026 |
Telemedicine does not decide whether an evacuation happens — the vessel master, the marine coordinator and the rescue coordination centre do, exactly as before. What a clinician-led telemedical service changes is the quality of the information that decision rests on: a structured clinical assessment, in real time, instead of a lay description of symptoms relayed through a radio chain.
That cuts both ways, and it should. In some cases the assessment confirms the casualty can be treated on site with the medical kit and trained first responders already there, with scheduled clinical follow-up. In others it does the opposite — identifying a time-critical condition earlier and giving the duty holder and rescue services a clearer clinical basis for tasking a helicopter without hesitation. Both outcomes are wins: the cost saved on the diversion that was not needed, and the time saved on the one that was.