By Capt. Neeraj Bharti, Founder, Master Mariner · Published · 2 min read
Underwater hull cleaning step by step: from enquiry to final report
For a superintendent booking a first in-water clean with a new contractor, the hardest part is often not knowing what will happen and when. This is the sequence a well-run job follows, from the first email to the report on your desk.
1. Enquiry
You send the basics: vessel name or IMO, port or anchorage, expected dates and window, time since last clean or docking, the scope you have in mind (hull, propeller, niche areas), and any photos or performance concerns. The more detail, the more accurate the quote.
2. Scoping and quote
The contractor confirms what is included, the method suited to your coating, whether capture is needed, the expected duration and price, and what the port requires. If the fouling level is unknown, an inspection first may be recommended.
3. Permissions
The contractor and agent arrange port and terminal permissions for diving and cleaning, and any environmental approvals. Some ports need several days' notice; some only allow daylight work.
4. Ship preparation
The ship prepares for divers working under the hull:
- Main engine and propeller locked out and shaft turning gear disengaged
- Thrusters isolated
- Sea chest suctions managed so divers are not drawn in
- Echo sounders, sonar and other underwater equipment switched off
- Cargo and ballast operations coordinated
- Diving flags and signals displayed
A written isolation checklist, signed by the ship and the dive supervisor, is the standard.
5. Arrival and safety briefing
The team arrives by launch or from the quay, sets up the dive station, and holds a toolbox talk with the duty officer covering isolations, communications and emergency procedures.
6. Pre-clean inspection
Divers inspect and film representative areas to confirm fouling type and coating condition. Any surprises, such as coating breakdown or damage, are reported to the ship and office before cleaning starts.
7. Cleaning
Brush carts work the flat bottom and vertical sides in a planned sequence; hand tools clean niche areas. The supervisor monitors progress and adjusts the method if the coating shows any sign of distress.
8. Niche areas and propeller
Sea chests and gratings, thruster tunnels, bilge keels, rudder and stern frame are cleaned by hand. If included, the propeller is polished as a separate stage.
9. Post-clean inspection
Divers film the cleaned areas to match the before footage, so the report shows a true comparison.
10. Report
The report covers fouling before and after, areas cleaned and any not cleaned (with reasons), coating and anode condition, and photographs and video by area. It goes into the vessel file and, where relevant, the biofouling record book.
How long it takes
Duration depends on hull area, fouling, niche areas, propeller, conditions and daylight rules. We cover this in its own article.
Booking with Cleanship
We work from bases in the UAE and India. See our underwater hull cleaning service, the complete guide to ship hull cleaning, or discuss your vessel's hull cleaning requirements.
Sources & further reading
Frequently asked questions
What are the steps in underwater hull cleaning?
Enquiry, scoping and quote, permissions, ship preparation and isolations, safety briefing, pre-clean inspection, cleaning, niche areas and propeller, post-clean inspection, and the report.
What does the ship need to do before divers work?
Lock out the main engine and propeller, isolate thrusters, manage sea chest suctions, switch off underwater equipment, coordinate cargo and ballast operations, and sign an isolation checklist with the dive supervisor.
Is an inspection done before cleaning?
A good contractor inspects representative areas first to confirm fouling type and coating condition, and reports anything unexpected before cleaning starts.
What should be in the final report?
Fouling before and after, areas cleaned and not cleaned, coating and anode condition, and labelled photographs and video by area.
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