The Effect of Ship Motion on Operability

In an ideal world, your crew would be able to carry out their tasks without any risk at all. However, the reality is much more complicated. When it comes to your marine operations, getting the job done is rarely straightforward. Various factors come into play, each with its own level of risk.

The ocean is constantly moving, and therefore, so is your ship. That motion can impact your operability, creating work windows wherein your crew can complete specific tasks.

That is why it is so essential for you to prepare a Hazard and Operability Study, better known as a HAZOP analysis. As the saying goes, forewarned is forearmed. So performing that risk assessment and knowing what your crew may face will help them work safely and efficiently. 

In this article, we will outline what is included in a HAZOP analysis. Then we will hone in specifically on the role of ship motion on operability and how you can chart a successful course with DTN Marine Weather API

Cargo ship in rough waters

What to include in a HAZOP analysis

HAZOP is a systemic review of the critical operations of your vessel. It looks at all the ways you can carry out a job and notes where problems may arise from an operational perspective. The goal is to highlight any potential risks or hazards that could impact operability.

Not only is it an effective way to ensure your staff and crew are kept safe, in many cases, but it is also one way to comply with local legislation. For example, the U.S. Occupational Safety and Health Administration and the European Agency for Safety and Health at Work require a Process Hazard Analysis (PHA), such as a HAZOP study, to identify and manage workplace hazards.

However, there are many other benefits to preparing a HAZOP analysis. First, your crew will be safer. Knowing what to expect and how to mitigate those risks if they arise will help them work with more confidence.

In addition, preparing a HAZOP analysis means you take proactive steps toward maintaining your vessel’s operability. In other words, it is one way of preventing any losses from occurring due to ship motion issues or operational limitations. The results are significant cost-savings, greater efficiency, and improved productivity. As you can see, the benefits of a HAZOP analysis are hard to deny.

Preparing a HAZOP study generally follows this process:

  • First, outline each step in a process and its parameters.
  • Then, identify potential deviations and consider what would happen if there was a deviation from the design or process. 
  • Next, consider hazard identification and evaluation. How would each hazard affect the process’ safety? Perform a risk analysis and determine how likely it is for this hazard to occur. 
  • Implement appropriate safeguards.

As you prepare your HAZOP study, you may note various areas in which the ship’s motion will cause a deviation from the parameters that you set during that exercise. So let’s zero in on that specific risk.

Ship in rough sea near offshore wind farm

Changes to ship motion

What causes a ship’s motion to create a risk to its operability? 

Simply put – weather. You know that weather is one of your biggest challenges. The weather affects a ship’s motion because the sea state can cause your vessel to have a different level of stability, depending on the wind and waves.

Weather can cause excessive heeling, which can lead to a loss of speed and maneuverability. This may be exacerbated by the amount of freeboard on your ship. 

Your ship’s motion may impact its operability if you cannot maintain its speed or maneuverability during inclement weather conditions.

That change in motion will affect the work being done inside the ship. It will impact how effectively your crew members carry out their tasks, both in terms of time and cost. In other words, it will affect operability – not just because of additional stress being placed on ship components but also because the tasks themselves may take longer and require more resources.

A ship’s dynamic stability in waves can be exacerbated by cargo and equipment on board, which will affect the vessel’s center of gravity.

Operability can be more functional, such as holding a vessel steady against an offshore windmill foundation or launching and recovering a dinghy safely on board. Many issues related to the dynamic stability of the ship in waves are also considered operability limits. Some examples include the steerability of a high-speed marine vehicle in waves or the dynamic stability of a vessel against excessive heeling in extreme sea states.


How to mitigate ship motion risks

There are several ways for you to mitigate risk when it comes to ship motion. 

First, you can take a proactive approach by ensuring that your vessel can operate safely in all weather conditions.

You need to look at how the tools and technologies aboard could be affected when it comes to operability risks from ship motion. You’ll want to consider things like crew fatigue or seasickness during extreme sea states.

Secondly, you will want to ensure that the weather is appropriate for the tasks that you want to do. Again, this is where your marine weather data and metocean forecast models are going to be critical.

Not all weather information is created equal, and not all solutions give you the operational insight needed for your risk management while at sea. Of course, you may need to make fast decisions. How can you do so confidently? How can you access reliable weather data to reduce the impact of metocean weather conditions?

Inside offshore vessel

The DTN advantage

With DTN Marine Weather API, you have an all-in-one solution that integrates our marine weather data and analytics into your systems. Access metocean weather content where you need it the most. We ensure that the data you rely upon to keep your crew safe is continuously validated, calibrated, and adjusted.

Get a wealth of knowledge with an extensive collection of marine weather content that includes 500+ marine weather variables, including ocean waves, atmospheric and tidal information. As well, you can also access 24/7 support and expertise from our master mariner meteorologists. Quickly access new features without changing your workflow through automatic onboarding into your existing account. 

Learn how to access timely, accurate marine weather forecasts and analytical data exactly when and where you need it with DTN Marine Weather API.