HOCl for Cruise & Marine

A ship is a sanitation problem with no back door. There is no chemical store down the road, no extra pallet space, no way to take a delivery mid-crossing, and a population of several thousand people sharing handrails, buffet tongs and lift buttons for a week at a time. When something goes wrong, it goes wrong in public and it is reported by name.

That combination is why onsite generation suits vessels unusually well. A generator turns a consumable that must be bunkered, stored and rationed into something the ship makes from salt, water and power, at a strength the crew sets. This page covers what that means in practice: the organisms that drive the risk, how the CDC Vessel Sanitation Program frames the requirements since its 2025 rewrite, where solution is used from galley to cabins to the technical spaces, and what it costs across a fleet.

What makes a ship different

Onsite generation does not change the epidemiology. What it changes is that solution stops being a stored, rationed consumable and becomes a utility the ship produces — which is the difference between a sanitation plan that survives a fourteen-day itinerary and one that degrades by day nine.

The organisms that drive risk here

That last point is worth stating plainly, because it is where most vessel sanitation material goes wrong. Norovirus is a surface and hands problem. Legionella is a water-system problem. They share almost no controls. A supplier who offers the same answer to both has not understood either.

The research hub indexes published work on hypochlorous acid against norovirus and its surrogates, including virucidal efficacy on surfaces against murine norovirus and liquid and fog application against human norovirus on surfaces, together with work on inactivation of Listeria monocytogenes biofilms by electrolysed oxidising water and on neutral electrolysed water on stainless steel. These are studies under their own test conditions, not claims for our systems; the pathogens page takes each one in turn.

What the research on hypochlorous acid shows

One distinction is worth keeping straight here, because it is the one this category blurs most often. An EcoloxTech system is a device that produces a hypochlorous acid solution on site. We make no efficacy claims for the device, or for the solution it produces. What follows is research on hypochlorous acid itself, under the conditions stated, and it is offered as exactly that.

In virucidal hard-surface efficacy testing by Microbac Laboratories Inc. (Sterling, Virginia, August 2018), a hypochlorous acid solution at 50 ppm free available chlorine was tested against murine norovirus strain MNV-G — the accepted surrogate for human norovirus, which cannot be routinely cultured — on a ceramic tile carrier, with a 5% serum soil load, at 21°C. The contact time was one minute.

Both solutions passed. Two things are worth drawing out. First, 50 ppm is a low figure next to the concentrations conventional chlorine protocols work at. Second, and more useful, the two rows differ only in pH — same chlorine concentration, same organism, same soil load, same contact time. At pH 5 almost all of the available chlorine is present as undissociated hypochlorous acid; by pH 8 much of it has shifted to the hypochlorite ion. That is the argument for specifying a set point rather than only a ppm figure, and it is why the pH of a solution matters as much as its strength.

Both reports are in the research library in full: the pH 5 report and the pH 8 report. They are sponsor-commissioned laboratory reports from a named independent laboratory, not peer-reviewed papers, and they describe one contact time under one set of conditions.

Research of this kind describes what was found under the conditions tested. It is not a claim for any product. Where a documented disinfection claim against a named organism is required, it comes from a registered product used according to its label — for us, HOCl-AS200 (EPA Reg. No. 101112-1), whose accepted label lists murine norovirus MNV-G at a five-minute contact time.

The 2025 VSP Standards, in outline

The CDC Vessel Sanitation Program applies to vessels carrying passengers on international voyages that call at US ports. In 2025 it replaced the long-standing Operations Manual with the Environmental Public Health Standards — a genuine rewrite rather than a reprint, and the reference point for anything you write into a procedure now.

Three parts of it shape a sanitation programme directly.

AGE surveillance. Acute gastroenteritis cases among passengers and crew are logged and reported on a fixed schedule: a report 36 to 24 hours before arrival at a US port, and a further update when four or more hours out if cases have risen but remain below 2%. At 2% or more of passengers or crew, VSP provides support and technical assistance. At 3% or more, the event is classified as an outbreak and investigation and response follow. A reportable case is three or more loose stools in 24 hours, or vomiting plus another symptom.

Those thresholds matter operationally because they turn a curve into a deadline. The gap between 1% and 3% can be a single day, and what happens in that day — how fast cleaning escalates, whether solution is available everywhere at once, whether crew can actually get it — decides which side of the threshold the voyage ends on.

Water systems. Potable water is monitored continuously rather than by spot check: electronic data loggers must record halogen levels for at least 16 hours in each 24-hour period. That is a plant-monitoring obligation, and it sits with the technical department rather than with housekeeping.

Recreational water facilities. The 2025 Standards tightened the Legionella regime: quarterly sampling for spa pools, whirlpool spas and heated jetted tubs, which can extend to six-monthly after 24 months of negative results, and jetted tubs drained daily. Again, plant and water management rather than surface work.

We have deliberately not printed specific halogen set points on this page. They belong to the current edition of the Standards and to your own operating procedures, and a number copied from a 2018-era supplier sheet into a 2026 procedure is precisely the kind of error an inspection finds. Compliance and inspections covers how to structure the records.

Where it is used, deck by deck

The outbreak curve, and why supply decides it

Every experienced vessel manager knows the shape. A handful of cases on day three. A jump on day four. A decision on day five about whether to escalate to the enhanced protocol, which multiplies solution demand across every public area, every toilet, every cabin corridor and every galley at once — at exactly the point in the voyage when stores are lowest.

A ship carrying bought-in concentrate faces that moment with a fixed quantity aboard. A ship generating its own faces it with a production rate. Those are different problems: one is rationing, the other is capacity planning. Sizing for the enhanced protocol rather than for routine use is the single most important decision in a vessel installation, and it is the one most often got wrong.

Two supporting points. Solution has to be where the work is — a draw point three decks away means buckets, reuse and skipped testing. And it has to be acceptable to use continuously in occupied public spaces, which is a practical argument for a near-neutral solution at use strength over a pungent concentrate in a crowded atrium.

Sizing a system for a vessel

Storage deserves particular attention at sea, because warm, bright spaces are plentiful and cool dark ones are not. Published work on how these solutions hold their strength is indexed as stability of electrolysed oxidising water.

The economics across a fleet

Vessel economics differ from shoreside economics in one important way: the saving is per ship, but the decision is made for a fleet, and the fleet multiplies both the saving and the standardisation benefit. Identical procedures, identical logs and identical training across sister ships is worth a great deal when inspections are unannounced and crews rotate between hulls.

We have a real worked example: an EcoloxTech E-300 fleet analysis for Norwegian Cruise Line, showing per-ship chemical spend of roughly $285,000 a year falling to about $1,400, against approximately $130,000 of equipment, for a payback of around 5.5 months — and across 21 NCL ships, about $4.21 million a year. The full numbers, and the method behind them, are on ROI and savings and the vessel version is on the fleet ROI page.

Beyond chemicals, the lines that matter are stores space released, hazardous-goods handling removed, and the avoided cost of a single reportable outbreak — which in a public, published-score environment is the number that usually ends the discussion.

What it does not fix

• It is not a cleaner. Soil must be removed first. In a galley and in a cabin bathroom alike, the detergent step is what makes the sanitising step meaningful.
• It does not replace hand hygiene. Norovirus moves on hands. Availability, compliance and supervision do more than any chemistry.
• It does not manage Legionella. That is water-system design, temperature, flushing and monitoring under the Standards.
• It carries no label claims. Where a registered disinfectant is required — medical spaces, or a protocol that specifies one — use HOCl-AS200 per its label.
• It does not fix a schedule that does not fit the turnaround. If the protocol cannot be executed in the window available, the protocol is the problem.
• Ballast water is a different subject. Ballast treatment sits under the IMO convention and type-approved systems, and is outside this programme.

Beyond cruise: ferries, offshore and workboats

Cruise dominates the conversation because the inspection regime is public, but most vessels that benefit from onsite generation are not cruise ships. The constraints scale differently.

Two cautions. Vessels operating entirely outside US itineraries are not under VSP, and should work to their flag state, their port states and any applicable EU or WHO guidance instead — but the operational logic of generating rather than carrying is unchanged. And smaller vessels are sized by space and power long before they are sized by demand, so the survey question is usually “what will physically fit and run?” rather than “how much do we use?”.

Crew, training and turnover

The part of a vessel programme most often underestimated is people. Crew rotate, contracts end mid-season, and a housekeeping team can turn over substantially between one inspection and the next. A procedure that depends on the person who was trained at commissioning will not survive a year.

What works is the same discipline that works ashore, applied harder. Written procedures short enough to be read at speed, in the working language of the crew who use them. Training recorded by name and date, repeated at each crew change rather than annually. Test kits at the draw point, not in an office. Logs simple enough that they get completed honestly under pressure — a column of invented numbers is worse than no log, and an inspector can usually tell.

There is one genuine advantage at sea: the crew live with the consequences. A housekeeping team that has worked through an outbreak needs no persuading about hand hygiene or high-touch frequency. The training that lands is the training that explains the 2% and 3% thresholds and what each person’s task does to that curve, rather than the training that recites a set point.

The rest of this programme

This pillar is the overview. Six companion pages go deeper:

• Pathogens — norovirus, Legionella, the galley organisms and what each one needs.
• Applications — deck by deck, from galley to cabins to the technical spaces.
• vs. Chemicals — what a ship can actually store, carry and use at sea.
• Compliance & inspections — VSP, AGE surveillance and inspection day.
• ROI & savings — the fleet model, with a real example.
• Implementation & SOP — installing on a ship in service.

Frequently asked questions

The seven-part programme