By Boud Van Rompay, CEO of Hydrex and Subsea Industries

Underwater hull cleaning promises to give ship owners lower fuel bills, but it isn’t always that simple.

Underwater cleaning operations were largely banned in the 1990’s, but recent approvals have been granted in several ports for cleaning carts with “reclaim” systems.

Whether or not the “reclaim” systems actually work, there is a bigger question: are the ship hulls actually washable?

Washable coatings

In an ideal world all ships would depart from port with perfectly clean hulls. In that condition they would always give the best possible fuel performance, and they would carry no invasive species.

For that to work, hull coatings would have to be washable. Unfortunately neither anti-fouling coatings nor silicone-based ‘release’ coatings can withstand cleaning operations .

If you’ve ever tried to pull a barnacle off a ship, you’ll understand how much force a coating would have to withstand.

After a couple of cleanings, these coatings degrade dramatically. A quick glance at any hull entering drydock shows flaked, blistered, cracked, chipped hull coatings , so rough that any idea of performance is a dream. It’s hardly surprising: the coatings are designed to wear away. It’s called “self-polishing”, and it usually means a complete re-coating job is needed at drydock.

If the stress of underwater hull cleaning is added to the wear and tear of normal operations, most coatings will have long failed.

There are washable coatings – and I have to come clean and say that my company makes a full range of them.

A washable coating is designed to be cleaned as often as needed without losing effectiveness – it always operates at peak efficiency. The washable coatings also last the lifetime of the ship, so neither the coating nor the owner’s bank balance need to wear away.

Good for Yards

Washable coatings are good news for Yards. No more weather problems, no more wasted time waiting for the paint to dry, and a boatload of environmental problems avoided with both authorities and public.

A simple high-pressure wash on entering drydock, some touch-ups on mechanical damage, and the coating is good to go back for another 5 years.

With washable coatings, Yards can get on with the work they do best, and everyone wins