Underwater Hull Cleaning in Suez and Egyptian Ports

The 2023 IMO Biofouling Guidelines (resolution MEPC.378(80), which revoked the 2011 version) set a rating scale that is the most practical starting point a superintendent has. Rating 1 is microfouling only, the slime layer, with paint still visible beneath it. Rating 2 is light macrofouling over 1 to 15 per cent of the area, growth that cannot be wiped off by hand. Rating 3 is 16 to 40 per cent. Rating 4 is 41 to 100 per cent.

Each band carries a different action. At rating 1, proactive cleaning may be appropriate. From rating 2 upward, cleaning with capture is the recommended route and the interval to the next inspection should shorten. The guidelines then add a line contractors rarely quote back to owners: where the anti-fouling system is significantly deteriorated, what is recommended is drydocking with reapplication of the coating, not another clean.

So the answer is sometimes no. A hull at rating 4 over a coating at the end of its service life is a docking job. Cleaning it afloat will remove the growth, take coating with it, and leave a rougher surface that fouls again faster.

Microfouling is slime and early weed. It sits lightly, it comes away with soft tools or gentle brushing, and removing it early is the whole logic behind cleaning little and often.

Macrofouling is barnacles, tubeworms, mussels, bryozoans and heavy algal fronds, bonded to the coating. Removing it means applying enough force to break that bond, and whatever breaks the bond also acts on the paint film underneath. That is where coating damage happens. Barnacles do not always come away whole either: capture trials have found base plates left on the surface after the shell is gone, ready substrate for the next generation.

Regulators draw their lines on exactly this distinction. Washington State's guidance describes allowing in-water cleaning of hulls carrying only slime and sea grass, while not allowing it for hulls carrying juvenile or adult barnacles, mussels and tubeworms. If your hull has visible shell growth, expect every conversation about it to be harder.

Anti-fouling systems fall into families that tolerate very different treatment, and the difference is physical rather than a matter of opinion.

IMO's 2025 guidance on in-water cleaning (MEPC.1/Circ.918) turns this into a documented question rather than an operator's judgement. Before work starts, the service provider is expected to hold the coating manufacturer's information showing the method suits that coating, evidence the cleaning system has been tested on that coating type, and a pre-cleaning inspection of the actual film. The same guidance defines coating damage bluntly: peeling, blistering, flaking, delamination, brush marks and swirls, scrapes, scratches, exposed metal, polish-through.

We fix the method in the job-specific method statement once the paint record and the pre-cleaning inspection are in front of us. That is why we ask for the paint record before we ask for the ETA.

There is no single global rule. In-water cleaning is permitted, restricted or refused by the State and port where the vessel is lying, and those rules have tightened almost everywhere over the last decade.

The IMO guidelines say reactive cleaning should be performed in an area accepted by the relevant authority, and that proactive cleaning without capture should not be carried out on fouling rated 2 or above. Where a jurisdiction assesses requests case by case, MEPC.1/Circ.918 sets out what it will want to see: the Biofouling Management Plan and Record Book, the anti-fouling certificate, coating type and remaining service life, fouling rating and coverage, whether the growth was accumulated in the same waters, the cleaning system to be used, and the arrangements for storing and disposing of captured material. A standard request form is annexed to it.

The specifics vary sharply. Capture thresholds proposed or applied by different bodies run from filtration of particles above 10 micrometres, through 15 micrometres, to Dutch requirements in the region of 0.5 to 1 micrometre. Australia has required biofouling management reporting from every international arrival since 15 June 2022. New Zealand sets a clean-hull threshold before arrival and allows more growth on short-stay vessels calling only at approved ports. California restricts in-water hull cleaning to best available technology and does not allow it on biocidal coatings in waters already impaired for those metals.

The Suez Canal Authority's maritime salvage and underwater works page lists underwater fouling removal, propeller cleaning and sea-chest work among its canal-zone functions; that page is not a substitute for confirming permission for a specific berth. For a job in Egypt we publish no claim about what a given port or the canal authority will allow, because that is the authority's decision and it moves. Tell us the berth and the date, we will tell you what the cleaning plan has to show, and permission is confirmed through the vessel's agent before anyone mobilises.

The Gulf of Suez and the Red Sea are high fouling-pressure waters. Summer surface temperatures in the northern Red Sea sit in the low thirties Celsius, with higher values recorded in sheltered lagoons, and salinity is high. Warm water accelerates settlement, so an idle period here builds macrofouling faster than the same period in a temperate port. A vessel sitting for weeks on a convoy slot in July is not in the condition its coating was specified for.

The site sets the rest of the constraints. Visibility governs whether a proper pre-cleaning inspection can be recorded at all, and the IMO guidance is clear that cleaning should not proceed without an adequate one, with rescheduling or moving to a better location as the stated alternatives. Current at canal anchorages, under-keel clearance over the tide, quay clearance and fenders alongside, and traffic movements around the berth all shape the sequence. Silt and reduced visibility weigh more heavily at Alexandria than at Suez.

The ship's side of the job is not optional. Propulsion and thrusters are immobilised and tagged out, with the diver or supervisor witnessing the lock and tag before anyone enters the water. Sea suctions in the working area are shut down or their status formally agreed, ballasting and bunkering are deconflicted, and impressed-current cathodic protection is powered off while divers are on the hull. Before any lockout is released, three things get confirmed: every grating restored, every person out of the water, all equipment recovered. Sea-chest work internals are a separate scope with their own isolation and permit regime, and propeller and running gear polishing is quoted alongside but finished to different standards.

For a wider vessel condition record, see hull inspection and the broader underwater inspection service; class-attended eligibility is covered in the in-water survey and class requirements guide.