Underwater Ship Surveys and Their Importance

As it is with marine surveyors, underwater surveyors are able to run some checks, report and provide worthwhile recommendations to evolving maintenance issues emanating from owners and operators of commercial ships be it on-sea or at the port. Oftentimes, an underwater ship surveyor offers survey services for In Water Surveys, UWILDS and damage investigations. Others include pre-purchase surveys, P&I surveys, stability surveys, stowage and a couple of others. In this blog post, we’ll discuss all these things – what they entail and how they can help in situations like these.


What is Underwater Ship Survey?

A survey(inspection)  is a way of assessing the technical condition of a ship to ensure it complies with all regulations and standards. Scheduled inspections are important because they allow any problems in the vessel to be identified early so, they can be fixed before anything bad happens. Unscheduled inspections are also necessary because if there is ever an emergency or accident, it would require making sure the ship was in good working order first.

For the sake of carrying out an underwater ship survey, it is necessary for surveyors to be well-equipped in knowledge and adept with practical skills that will aid them when looking at every detail about the vessel as well as performing each task on board. These tasks can include carrying out in-water class surveys, hull cleaning, taking video or photography underwater, surveying using sonar waves, inspecting ballast tanks and executing other routine maintenance procedures.

Why Is An Underwater Ship Survey Important?

Underwater ship survey is an unavoidable and essential factor. As a solution underwater inspections became common, it involved getting highly qualified and experienced divers who could dive underwater check and identify imminent problems beneath the waterline and offer immediate solutions for them. Underwater surveys are more of a precautionary measure taken to avoid prolonged repairs anytime in the future.

According to the Classification society, large vessels are required to undergo a thorough inspection every year and have a secondary inspection every three years in order to remain certified to be in operation. Classifications existed from the second half of the 18th century (IACS 2011) for providing technical assessments for marine insurers. Classifications started as a program for insurers to protect their interest but it later progressed into a fair assessment by a third-party organization that keeps their stakeholder’s interests their top priority.

The ultimate goal of having certified vessels compared to vessels that are suspended or non-certified is to protect owners, employees, insurers and the companies who depend on these vessels. Classifications societies have no interest in the commercial side of the shipping industry, credibility is their main source of business


Types of Underwater Surveys


In-Water Survey is a method of surveying the underwater parts of the ship while it remains afloat. IWS provides all the possible information regarding the condition of the vessel’s underwater hull and other vessel parts. IWS can be conducted during normal vessel cargo operations. It reduces vessel downtime, additional travel, and expensive dry-docking cost.



Underwater ship inspections require competent and certified divers that go beneath the surface of the water line. This practice helps ship owners, managers, and financiers to identify potential problems before they occur. Inspections also ensure that extensive or costly repairs will be avoided at a later date when found sooner.



Sea chests are cavities built into a vessel’s hull to help increase the efficiency of pumping seawater into the internal pipework system to support the vessel’s engine cooling, ballast, and firefighting purposes. These grids called ‘sea chest gratings’ prevent the passage of large objects such as trash, fish, nets, etc. these inspections help to identify any extent of damage prevailing in the sea chest.



A ship’s hull is considered to be the main structural element of the ship. By regular maintenance and inspection, sailing is made easier and safer. Usually, ROV or Remote Operated Vehicles are made use of for hull inspections as they are faster, easier, and more effective.



 CCTV inspections allow us to accurately record and see the present condition of the vessel that cannot be visually inspected during routine inspections because of excessive water depths or turbidity. Clients can monitor real-time footage of the submerged surface during CCTV inspection. Each diver reports on the ship’s condition below the waterline.


Some other underwater surveys include the following


 This survey needs the vessel to be dry docked. It is conducted every 2 years or twice in 5 years. The survey inspects underwater fittings and hull fittings, special attention is given to underwater shell plating. This can be exempted for vessels that carried out In Water Survey.


Following repairs, a survey is again conducted to assess the status of the vessel to determine if the vessel has been restored to a condition meeting the requirements of the surveyor. Temporary repairs may be permitted by the issuance of an appropriate recommendation or state of the class.


In order to establish the extent of damages incurred, insurance companies require a damage survey report. Along with this they also need an estimate for the repair costs and necessary work that needs to be done.


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