Harbour masters and port operations: the wind call, at your height

As a Harbour Master or Port Operations Manager, you make daily decisions that depend on accurate wind information. These decisions can include restricting vessel movements, assigning additional tugs, or suspending pilot boarding. In extreme conditions, you may need to close the channel entirely.

These are not routine calls; they are event-driven, particularly during gale conditions. A wrong call can lead to significant ship delays and berth window disruptions, impacting port efficiency and costing time.

Your port notices and operational documents, such as the Dublin Port towage matrix, set the specific wind limits that trigger these actions. For example, a mean wind of 20 knots might require a specific towage assignment. When a Red weather warning is issued, your channel might close two hours before the warning period and remain closed for two hours after it lifts.

Making the correct call relies on precise, location-specific wind data. The instrument helps you assess the likelihood of exceeding your operational limits, allowing you to make timely and informed decisions based on your port's established protocols.

For port operations, the critical wind data is typically at 10 metres, which is the height of a ship's bridge or a berth-side crane. The instrument provides wind at this height, along with gusts, interpolated to your precise working height in metres. It distinguishes between the mean wind and gusts, as both are crucial for different operational thresholds.

Your operational limits are set by your port's own documents. For example, the Dublin Port towage matrix applies below a 20-knot mean wind. These limits are not arbitrary; they are established based on the handling of vessels, pilotage procedures, and berth operations.

Understanding the difference between mean wind and gusts is vital. A mean wind might be within limits, but a sudden gust could exceed a critical threshold for a specific manoeuvre. The instrument displays both, allowing you to assess the full wind profile relevant to your daily operations.

By inputting your specific working height and limits, you get a tailored view of the wind that directly applies to your operational decisions, rather than relying on general forecasts.

The instrument shows you the probability (P) of the wind exceeding your set limit for each hour. This is calculated from an ensemble of weather models, where P(above your limit) is the fraction of these models that predict wind above your threshold at 10, 80, 100, or 120 metres, interpolated to your working height.

The Agreement Spine shows where these weather models concur or diverge. When models largely agree, you have a higher confidence in the forecast. When they disagree, it highlights uncertainty, prompting a more cautious approach.

For example, if the odds show a 20 per cent chance of exceeding your limit, you might proceed with caution, perhaps with an extra tug on standby. If the odds are 50 per cent, you might consider delaying a pilot boarding or restricting certain movements. At 80 per cent, you would likely implement a full restriction, such as assigning more tugs or closing a specific berth.

These percentages are not absolute certainties but indicators of risk, allowing you to align your operational response with the likelihood of exceeding your established limits.

This is an example of how you might use the instrument during a typical day at the port:

• 06:00: You check the instrument before the morning brief. It shows a 10 per cent chance of mean wind exceeding 20 knots at 10 metres between 14:00 and 16:00, with gusts possibly reaching 30 knots. The Agreement Spine shows good model agreement for the morning, but some divergence for the afternoon, suggesting increased uncertainty.
• 07:00: During the morning brief, you advise your team of potential wind increases in the afternoon, noting the 10 per cent chance of exceeding the 20-knot mean wind limit. You decide to monitor the situation.
• 11:00: The forecast updates. The odds of mean wind exceeding 20 knots between 14:00 and 16:00 have risen to 40 per cent. Gusts are now forecast to reach 35 knots, with increased model disagreement on the Agreement Spine. You decide to assign an additional tug for a vessel due to berth at 15:00.
• 13:00: A further update shows the odds of exceeding 20 knots have increased to 60 per cent, and gusts are consistently forecast above 35 knots. You issue a restriction on pilot boarding for the afternoon and delay the berthing of the 15:00 vessel by two hours.
• 15:00: The actual wind measured at the berth shows mean wind at 18 knots with gusts to 32 knots, confirming your cautious approach was appropriate. The instrument's record page captures this forecast and the actual conditions.

Your operational limits for wind are not generic; they are specific to your port and are detailed in your official documents, such as port notices or towage matrices. For example, the Dublin Port towage matrix specifies conditions below 20 knots mean wind. You will input these precise values into the instrument.

The instrument is preset to 10 metres, as this is the commonly cited height for marine operations. However, you can adjust this to any working height relevant to your specific task, such as the height of a particular crane or a vessel's highest point.

By typing in your exact limits from your own documentation, you ensure that the instrument's alerts and probability calculations are directly relevant to your port's rules and procedures. This removes the ambiguity of general forecasts and provides a clear, actionable reference point.

This customisation ensures that the instrument supports your decision-making process based on the established operational thresholds of your harbour, rather than generic meteorological advisories.

After an incident or a critical operational decision, you may need to demonstrate the basis for your actions. The instrument maintains a dated record page of what was forecast, what was observed, the specific wind limits you used, and the call you made. This provides a clear audit trail.

This record is vital for internal reviews, for reporting to the port board, or for any inquiries that might arise. It allows you to show precisely the information you had at the time of your decision, demonstrating due diligence and adherence to operational protocols.

For example, if a vessel experiences a delay due to wind restrictions, the record page can show the forecast that led to your decision to restrict movements. This verifiable record helps to explain and justify operational choices, particularly when dealing with commercial pressures or concerns.

Having a clear, immutable record of forecast versus actual conditions, alongside your decision, is a key component of responsible port management and accountability.

Ireland's geographical position means its ports are significantly exposed to Atlantic weather systems, particularly during the gale season, which typically runs from October to March. During this period, strong winds and storms are frequent, necessitating constant vigilance and robust operational planning.

Met Éireann, as the national forecaster, provides general weather advisories, but your operational decisions require more granular and specific wind data at your working height. The instrument helps bridge this gap by providing localised forecasts relevant to your port's specific conditions.

Irish port operations, like those in Dublin Port, often have detailed notices to mariners that outline wind thresholds for various activities. These documents are developed to manage the specific challenges posed by Ireland's weather.

Understanding the seasonal patterns and being prepared for rapid changes in wind conditions is paramount for maintaining efficient port operations in Ireland. The instrument helps you anticipate and respond to these conditions with precise, actionable data.