Water: The Shipboard Resource We Still Underestimate

Around 30 years ago — here he goes again — I was responsible for daily engine-room operations on a proper big boat.

There was often a “discussion” about water at the morning Shipboard Management Team meeting.

“Discussion” is being polite.

It was usually the Mate, invariably backed up by the Old Man, asking whether it was OK for the deck crew to use freshwater in their ongoing battle against corrosion above decks.

Otherwise known as deck maintenance.

At the time, water was simply another consumable that had to be managed. Drinking, cooking, accommodation and sanitary systems quite rightly took priority. Deck washing came further down the list.

I think we should look at it very differently today.

Modern Reverse Osmosis (RO) technology means seawater can be converted into high-quality water onboard, economically and with relatively low energy consumption.

And importantly, RO water isn't just for drinking.

Technical water can be more valuable than potable water

Ships consume water for accommodation, cooking and drinking, but also for cleaning, machinery maintenance, deck washing and a whole range of technical applications.

This is where the quality of RO-produced water becomes particularly interesting.

A properly designed RO system removes the vast majority of dissolved salts, producing water with extremely low chloride levels.

That makes RO technical water particularly useful for final deck rinsing and equipment cleaning.

Why does that matter?

Because chlorides and marine equipment are not good friends.

Salt left on decks, pipework, machinery, fittings and steelwork contributes to corrosion. Washing with low-chloride RO water helps remove salt contamination without simply putting another significant chloride load back onto the surface.

And that brings us to something shipowners understand very well:

The dry dock

Good deck maintenance isn't about making a ship look pretty.

It is about protecting the asset.

Poorly maintained decks and external equipment can mean more corrosion, more steelwork repairs, more coating preparation, more observations during inspections, more blasting and painting — and ultimately more work during dry docking.

And dry-dock time is expensive.

A vessel entering dry dock with significant corrosion and poorly maintained equipment can require substantially more remedial work, potentially extending the docking period as well as increasing the repair bill.

For an owner, preventing corrosion during the vessel's operating life is almost always cheaper than repairing it in dry dock.

So good-quality technical water isn't simply a housekeeping issue.

It can form part of the vessel's wider asset-maintenance and lifecycle-cost strategy.

Why use potable water for technical applications?

This is another question worth asking.

If you're washing a deck, cleaning machinery or carrying out another technical task, does the water really need to be potable?

Probably not.

So why use water that has been treated, stored and managed specifically for human consumption when an RO system can produce the appropriate technical water onboard?

Potable water for people.
Low-chloride RO water for technical applications.

Simple.

And much more logical.

The economics have changed

Modern membrane technology has made RO considerably more attractive.

Depending on the application and system configuration, modern units can produce substantial quantities of high-quality water at a production cost of less than $1 per cubic metre.

That changes the economics of onboard water production — particularly when you consider the alternatives.

Bespoke rather than off-the-shelf

This is where I work with a designer and manufacturer of bespoke RO solutions who are, quite simply, water nerds.

And I mean that as a compliment.

They love a challenge.

Rather than starting with an off-the-shelf package and trying to make it fit the vessel, we start with the requirement.

Is the requirement potable water, technical water — or both?

How much of which type of water is needed?

What is it going to be used for?

Where could the system be installed?

What’s the vessel’s typical trading pattern?

The system is then designed around the vessel and its actual requirements.

Perhaps the conversation about shipboard water needs to change

Thirty years ago, the morning discussion was about whether there was enough freshwater to let the Mate have a few tonnes.

Today, perhaps we should be asking better questions:

Why are we consuming freshwater when we can economically produce the right quality of water onboard to suit the specific requirement?

Why not give the Mate their own RO unit and let them washdown and coat as much as they need to?

RO is no longer simply a freshwater generator.

It can be an integral part of a vessel's water, maintenance, corrosion-control and sustainability strategy.

And if producing low-chloride technical water onboard helps keep decks and equipment cleaner, reduces corrosion and ultimately reduces the amount of work required during an expensive dry dock, then perhaps water isn't just another consumable after all.

It is an asset-management tool.