Why Ports and Jetties Need Regular Underwater Inspection
Why Ports and Jetties Need Regular Underwater Inspection India’s coastline stretches over 11,000 kilometers and along it sit some of the busiest ports in Asia, hundreds of fishing jetties, cargo terminals, naval installations, and private berths that move billions of dollars of goods every year. Most people who walk across a jetty or watch a vessel dock have no idea what is happening below the waterline. And that is exactly the problem we want to address. Underwater infrastructure does not announce its deterioration. There is no visible crack on the surface, no alarm, no warning light. By the time something shows above water, the damage underneath is usually already serious which is why regular inspection is the only way to know what is actually happening. What Is Actually Down There? A port or jetty sits on a foundation system that is constantly under attack from multiple directions at once. The water itself is corrosive, especially saltwater. Tidal movement means the structure is in a wet-dry cycle for hours every day, which accelerates deterioration at the splash zone, the area just above and below the waterline. Marine growth such as barnacles, mussels, and algae adds weight and traps moisture against the steel or concrete. Vessel impact happens routinely during berthing, and not all impacts get reported. Sediment shifts under the seabed and can undermine pile foundations over time. Steel piles corrode from the outside in. Concrete piles can suffer from chloride-induced corrosion of the internal rebar, which means the surface looks fine while the structural capacity is quietly reducing. Timber piles, still common in older Indian jetty structures, are vulnerable to marine borer attack, particularly organisms like Teredo navalis that hollow out the wood from the inside without any external sign until the pile is essentially a shell. None of this is visible from above. A drone flying over a jetty tells you nothing useful about its structural health. The Regulatory Side of It The Directorate General of Shipping, port trusts, and various state maritime boards have inspection requirements for port infrastructure, but enforcement and frequency vary considerably. Lloyd’s Register, Bureau Veritas, and Indian Register of Shipping each have their own survey cycles for structures under their class. Insurance providers often require inspection reports before renewing marine infrastructure coverage. In the event of a structural failure or incident, the absence of inspection records creates serious liability exposure for port operators and asset owners. Beyond compliance, there is a simple financial argument. A routine underwater inspection that catches a corroded pile cluster early costs a fraction of what emergency repair costs after a partial collapse. Emergency mobilisation, unplanned berth closure, potential loss of cargo or equipment, and regulatory scrutiny after an incident can together cost many times more than a decade of preventive inspection would have. What an Underwater Inspection Actually Involves A proper underwater inspection of port or jetty infrastructure is not just a diver going for a swim with a torch. It follows a structured methodology. The pre-dive phase involves reviewing existing drawings, prior inspection reports if available, any known incident history, and the specific areas of concern. Inspection points are planned systematically so that nothing is missed and so that results can be compared to previous surveys at the same reference locations. During the inspection, divers physically examine each pile or structural element. They are looking at surface condition, any signs of corrosion, marine growth patterns, impact damage, cracking in concrete, section loss in steel, and signs of scour or sediment undermining the base of piles. Measurements are taken at defined points and depths. Hammer-sounding is used on concrete to identify delamination or hollow areas that are invisible to the eye. Cathodic protection systems, where fitted, are checked for anode condition and continuity. Documentation is central to any inspection worth calling one. Video recording, still photography, and written condition reports with a clear rating system for each element allow the asset owner to understand exactly what was found, where, and how serious it is. A good inspection report does not just describe what is there. It tells you what needs immediate attention, what should be monitored at the next survey, and what is in acceptable condition. In more complex cases or where access is particularly difficult, inspection can be supplemented with ROV deployment for visual coverage, ultrasonic thickness gauging for steel sections, or impressed current monitoring for cathodic protection systems. But for the majority of Indian port and jetty inspections, experienced commercial divers with the right equipment and documentation process are the core of the work. Scour: The Risk That Gets Underestimated Of all the failure mechanisms affecting jetty and port foundations, scour is probably the one that gets the least attention from non-specialists. Scour is the erosion of the seabed material around and beneath foundation piles caused by water current and vessel propeller wash. When a large vessel manoeuvres using bow thrusters in a confined berth, the propeller wash can move significant amounts of seabed sediment. Over time, this can expose pile sections that were previously buried and reduce the lateral support that the seabed provides to the foundation. Scour holes form around pile groups and, if deep enough, can compromise the stability of the entire structure. Scour is essentially invisible until it is severe. Sonar bathymetry surveys and physical diver inspection of the seabed profile around piles are the only ways to detect it early. Remediation, when caught early, typically involves rock armour or concrete mattress placement. Remediation when caught late, after a foundation has shifted, is a far more complex and costly exercise. How Inspection Frequency Should Be Determined There is no single answer for how often a structure should be inspected underwater. It depends on age, construction material, operating environment, traffic intensity, and previous inspection findings. A general benchmark for structures in service is a major inspection every five years and an intermediate inspection at the midpoint. But this is a starting point, not a rule that fits every situation. Structures in highly aggressive
