The Dockmasters Journal - Volume 2, Issue 3
A publication focused on Dry Docks presented to Dock Masters, Dry Dock Engineers, Operators, and Owners
Published March 2025
Editor: Waleed (Wally) Sayed, P.E., M. ASCE
Our mission is to focus on the diverse world of dry dock facilities, showcase their successes and their unique capabilities, disseminate industry specific knowledge, and share lessons learned from dry dock incidents with a positive presentation.
In this month’s edition:
⦿ A Note from the Editor
⦿ Questions for the Editor
⦿ Main Article: Steel Eating Bacteria!?
⦿ Community Highlight
⦿ So, this one time, I was on a dry dock...
A Note from the Editor:
“A ship in dry dock is safe, but that’s not what ships are meant for.”
The Must-Attend Event for Drydocking Professionals in Providence, Rhode Island
The Dry Dock Conference brings together the sharpest minds in drydocking to tackle real challenges, share innovations, and connect with industry leaders.
The 11th International Dry Dock Conference and Advanced Training Forum is happening on June 4-5, 2025, at the Hilton Providence in Providence, Rhode Island, USA. This biennial event is for professionals in the drydocking industry. Attendees will gain expert insights, explore innovative solutions, and network with shipyards, government agencies, maritime organizations, and industry leaders. For more information and sign-up, visit: https://www.drydockconference.com
Triton Dry Dock Engineers, Marine Surveyors & Consultants LLC and Von Schmidt Maritime LLC are proud sponsors of the 11th International Dry Dock Conference, reinforcing their commitment to excellence, innovation, and leadership in the drydocking industry.
Questions for the Editor:
Q) Does my floating dry dock require a tank level indicator (TLI) system?
A) It is highly recommended to have a TLI system, and it is required for any IACS (ABS, DNV, Lloyds, etc.) classed steel floating dry dock. It is also required if the floating dry dock is certified under US Navy MIL-STD-1625 or US Coast Guard SFLC STD SPEC 8634 standards. When drydocking USN, USCG or any other DoD vessel, the requisite engineered pumping plan cannot be followed without a TLI system.
A TLI system provides the dock operator with crucial real time information regarding the sequence of ballast operations. While many shipyards operate short floating dry docks (<200-ft) without a TLI system every day, it is the equivalent of driving a car without windows. The ballast levels should be differential, with lower ballast levels in the tanks below the vessels load. Too many floating dry dock failures have been attributed to improper ballasting due to the lack of a TLI system or failure to follow an engineered pumping plan.
Steel Eating Bacteria?
You may be asking yourself, is this a real topic or click bait? Steel eating bacteria is very real. If you have ever found a rust-colored blob in your ballast tanks, it wasn’t rust, it was steel eating bacteria. The concept of extremophiles, or organisms that exist in extreme conditions, was mostly unknown until 1965. That is when the husband-wife biologists Thomas and Loise Brock were visiting Emerald Pool in the Upper Geyser Basin of Yellowstone Park and for reasons unknown decided to take a sample of pond scum and look at it under a microscope. What they found were live organisms, Sulpholobus acidocaldarius and Thermophilus aquaticus, existing in conditions where no life was ever expected to be. This shocking revelation forever changed microbiology and thus began a series of unexpected if not disturbing discoveries.
Since that time, many varieties of extremophiles have been discovered that exist in extreme heat (thermophiles), cold (cryophiles), acid (acidophiles), and salt (halophiles). In the walls of deep ocean thermal vents where temperatures exceed 235°F, Pyrolobus fumarii finds life to be perfectly suitable. Deinococcus radiodurans finds radioactive wastewater very pleasant to live in. The most interesting are those that exist without oxygen, or anaerobic bacteria. These types can cause lethal damage to the human body, and they can also eat metal.
Metal oxidizing bacteria are organisms that derive life sustaining energy by consuming metal. Thiobacillus ferrooxidans, Leptospirillum ferriphilum, and Halomonas titanicae are some examples. In each case there is a symbiotic relationship between an anaerobic sulfate-reducing bacteria and a total general bacterium that creates an anaerobic environment thus shielding the sulfate-reducing bacteria beneath it. While microbiologists see great positive potential uses for these bacteria in the areas of recycling, ship and dry dock owners do not.
Many paints used in shipbuilding have metals in them including zinc, chromium and iron. While we generally consider coating systems on steel hulls to be the best form of preservation, metal oxidizing steel eating bacteria find them to be scrumptious. Since these bacteria are found throughout our salty ocean waters, they are constantly cycled through ship and dry dock piping and eventually find themselves in ballast tanks. It is these areas where there are low cycle rates, limited turbulence, and stagnation which over time results in reduced oxygen levels that awakens the steel eating bacteria symbiosis. Once these bacteria have found a suitable amount of metal in the coating system, they begin to propagate rapidly. Eventually these bacteria will eat through the coating system and begin consuming the steel below it. Left unattended, they will eat holes into your steel hull.
In the experience of the editor, steel eating bacteria have been observed in steel floating dry docks in every saltwater body on Earth. When inspecting steel hulls, typical corrosion is rust colored oxidized steel with the observable presence of rust staining, rust film, pitting and/or scaling. While the appearance of steel eating bacteria is rust colored, it is because the total general bacterium has consumed iron broken down by the sulfate reducing bacteria which oxidized in the presence of waterborne oxygen. Its appearance is different than typical oxidized steel, in which it appears as a rust-colored blob (the total general bacteria) which when hand scraped reveals a black sludge beneath it (the sulfate reducing bacteria) and then bright white unoxidized steel which is usually deeply pitted due to bacterial consumption.
While steel eating bacteria has been observed eating through hull coatings, piping, and valve bodies, one of the easiest material sources in ballast tanks is waste metal such as welding slag, welding rods and waste metal left behind from tank repairs. These waste materials become the easiest source of metal as they are unprotected and readily available for consumption by steel eating bacteria. Once the steel eating bacteria has propagated on the waste metal, attacking coated steel and the steel hull below occurs rapidly.
The photos below are from a steel floating dry dock ballast tank in saltwater. In the left photo, a piece of waste metal was found in-situ on the bottom of a ballast tank with 12-inches of residual ballast water and ¼” of silt. Note the presence of the rust-colored blob on the large piece of waste metal. There are other smaller formations on the welding rods left behind that surround the waste metal. In the right photo, the rust-colored formation (A, total general bacteria) was hand scraped, revealing the blackened sludge (B, sulfate reducing bacteria) and beneath it is bright white (C, gray) metal. Note the small bacterial formations on the coated bent plate stiffener the scraped waste metal is resting on.
While labs kill these bacteria with chloroform, this is not a viable solution since these bacteria are naturally occurring in all bodies of saltwater. If these blobs are found, the best solution is to thoroughly pressure wash the area to completely remove the growth and expose the white metal, prepare the area for coating, and prime and coat the damaged area. Ultrasonic thickness (UT) measurements should be taken on the bare metal to determine if repairs are required prior to recoating. Next is to ensure proper flushing of the ballast tanks to remove any residual bacterial growth. Prevention is to remove all metal waste from the ballast tanks when making hull repairs, and to fully cycle the ballast tanks, to the point of stripping all water from the tanks, at least every 6 months, as this seems to be the time it takes for the stagnation effect to take place.
Community Highlight
Michael Sweeney is a maritime professional with an extensive shipyard career. He has dedicated himself to shipbuilding with decades of experience working with multiple shipyards across the southeast coast including Bender Shipyard, North Florida Shipyard and Fincantieri Marine Repair.
Staring as a Shipyard Painter, he worked his way up to be a Shipfitter, a Welding Foreman and a Certified Weld Instructor (CWI). He has also been an Erection Foreman, Test and Trial Manager and a Ship Construction Project Manager.
He has 21 years of experience as a DockMaster, receiving his MIL-STD-1625 Dry Dock Safety Training from NOESIS. He has commercially commanded two 4,500LT ARD’s, an 18,000LT AFDM, a 17,500LT floating dock, a 1,600LT AFDL, and a 600MT TraveLift™.
He has extensive experience with rolling transfers and was the DockMaster for the rolling transfer of a 2,500LT LCS class vessel launched from Austal USA in Mobile, AL. He is currently the DockMaster at Fincantieri Marine Repair, Jacksonville, FL.
So, this one time, I was on a dry dock...
So, this one time, I was on a dry dock…within 24-hours of receiving a phone call regarding an emergent floating dry dock incident. The dock crew had come into the shipyard that morning to find their unloaded steel floating dry dock half sunk, with the forward corner partially submerged and the opposite aft corner raised, with combined list and trim with torsion. The dock control room was found to be fully secured and there were no signs of tampering. The control board was fully operational, and a complete valve and pump line up revealed no anomalies. The crew noted the inexplicably flooded tanks and proceeded to deballast the entire dock for a hull inspection.
With the dock fully dewatered the same tanks began to inexplicably flood again and the dock quickly resumed its former half sunk condition with the forward corner partially submerged and the opposite aft corner raised. Divers were called in to look for external hull damage and could find no obvious hull damage. A 24-hour watch was posted and the tanks were prepared and gas-freed for an internal hull inspection.
During the internal inspection, numerous rust-colored blobs were found across the bottom structure and bottom plate of the ballast tanks. When the rust-colored blobs were hand scraped, they revealed black sludge and bright white metal with deep pits, a clear sign of steel eating bacteria. Many of the deeply pitted areas in the bottom plate were found to have holed through the entire thickness of the bottom plate, breaching the watertight integrity of the ballast tanks which was the direct cause of the flooded ballast tanks. The steel-eating bacteria blobs were found throughout the entirety of the dock but were most prevalent in the forward section of the dry dock where the most extensive damage was identified.
During the hull inspection it was noted that the dry dock had been idled for several months during an extensive ship overhaul and had recently undocked the vessel. It was suspected that the extensive idle period had caused the waterborne oxygen levels to drop low enough to allow for anaerobic growth of the symbiotic steel eating bacteria growth and given the metal content of the coating system the steel eating bacteria had been able to propagate at an accelerated rate.
The solution was to pressure wash the interior bottom portion of the hull and repeatedly flush the tanks prior to making repairs. Each hole or deep pit was isolated and plug welded, then each repair was primed and recoated.
Triton Dry Dock is a Premier Dry Dock Engineering Firm With Extensive Experience in Designing, Modifying, Analyzing, Inspecting and Certifying Dry Dock Facilities. You Can Trust Triton Dry Dock to Provide Your Shipyard With the Most Effective and Efficient Dry Dock Solutions.
Next edition:
✅ Floating Dry Dock Transverse Bending
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📩 Reach out to Wally at wally@tritondrydock.com—we’re looking forward to hearing from you!
Disclosure: Waleed Sayed, P.E. is a co-author of “ASCE Manuals and Reports on Engineering Practice No. 121, Safe Operation and Maintenance of Dry Dock Facilities” and a co-author and voting member of “ASCE/COPRI Standard 77-22, Dry Dock Standard”. Mr. Sayed is not compensated for presenting any information related to these publications. This publication was developed and produced without any assistance from Artificial Intelligence (AI).
Disclaimer: The information provided in this publication is general in nature and not prescriptive to any specific dry dock facility. Always consult a qualified professional when developing any site-specific plan.
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