Marine pilots and tug / towage operators: the wind call, at your height

As a Pilot, Tug Master, or Marine Superintendent, you make critical decisions multiple times a day, for every ship movement. Your calls involve whether to board a vessel at the pilot station, how many tugs to assign for a manoeuvre, or if a move should be delayed entirely. These decisions are directly influenced by wind conditions.

A wrong call can lead to significant operational delays and potential issues. While the financial cost of these delays is not always quantified, the impact of idle tug hours and delayed vessels is clear. More importantly, pilot transfer at sea is a high-risk activity, making accurate wind assessment vital for personnel.

Your decisions are guided by specific wind limits, often set by the Harbour Master and pilot master under the Harbours Act 1996 pilotage provisions. These limits determine when conditions are suitable for various operations. The instrument helps you assess the likelihood of exceeding these limits, supporting your decision-making process for each vessel movement.

For pilotage and towage operations, the wind at the pilot boarding ground is paramount. Your operational limits are typically set for mean wind speed and gust at this specific location. The instrument provides wind data at 10, 80, 120, and 180 metres, interpolated to your working height, which is 10 metres for your operations.

It is important to distinguish between mean wind and gusts. Gusts are transient, short-duration increases in wind speed, while the mean wind is an average over a longer period. Both are critical for your decision-making, as sudden gusts can pose significant challenges during pilot transfers or complex towage manoeuvres. The instrument presents gusts alongside the mean wind speed.

Your operational limit, such as 20 knots mean wind for towage as referenced in Dublin Port's towage matrix, is a threshold you enter into the instrument. This allows the system to compute the likelihood of conditions exceeding your specific limit, directly supporting your operational protocols.

The instrument shows P(above your limit) by the hour, which is the fraction of ensemble members that predict wind speeds will exceed your specified limit. For marine pilots and tug operators, understanding these odds is key to managing risk.

If the instrument shows 20 per cent P(above your limit), it means one in five model runs anticipate exceeding your threshold. This might indicate a low risk, allowing you to proceed with a standard operation, perhaps with heightened vigilance. If the odds rise to 50 per cent, it suggests an even chance of exceeding your limit, prompting a more cautious approach, such as assigning an additional tug or preparing for a potential delay.

An 80 per cent P(above your limit) indicates a very high likelihood of exceeding your operational threshold. In such a scenario, the prudent decision would likely be to delay the move or take significant mitigating actions. The Agreement Spine shows where weather models agree or disagree, providing further insight into the forecast's certainty. High agreement often reinforces the reliability of the odds presented.

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

• 06:00: You check the forecast for a vessel due to arrive at 10:00. The instrument shows a 10 per cent chance of exceeding your 20-knot mean wind limit at the pilot boarding ground, with mean wind forecast at 12 knots and gusts to 18 knots. You decide to proceed with the planned two tugs.
• 08:30: A new forecast update shows the odds for the 10:00 window have increased to 30 per cent, with mean wind now forecast at 17 knots and gusts to 24 knots. You consider the option of a third tug, but decide to wait for the next update.
• 09:30: The odds for 10:00 have jumped to 60 per cent, with mean wind at 21 knots and gusts to 28 knots. You instruct the pilot to delay boarding until the 11:00 window, which shows 20 per cent odds.
• 10:45: The 11:00 window now shows 15 per cent odds, mean wind 14 knots, gusts 20 knots. You confirm the pilot transfer and two-tug towage for the vessel, now with a slight delay.

Your operational decisions are governed by wind limits specified in your own port documents, such as towage matrices or pilotage guidelines. For instance, Dublin Port's towage matrix applies below 20 knots mean wind, indicating a critical threshold for your operations. These documents, often established by the Harbour Master and pilot master under the Harbours Act 1996, define the parameters for sound and efficient vessel movements.

You will input your specific wind limit into the instrument. For your operations, the instrument is preset to a working height of 10 metres. You can adjust the limit to match the exact value from your document, whether it is 20 knots mean wind or another specific threshold. This ensures that the odds displayed are directly relevant to your operational procedures and regulatory requirements.

By accurately reflecting your documented limits, the instrument provides tailored information, allowing you to quickly assess the risk of exceeding these thresholds at the pilot boarding ground. This precision supports your decision-making, ensuring adherence to your established protocols.

The instrument provides a dated record page of what was forecast, what was observed, the limit you used, and the call you made. This record serves as an important audit trail for your operational decisions.

In your role as a Pilot, Tug Master, or Marine Superintendent, you are often required to justify decisions, especially those involving delays or deviations from routine operations. A comprehensive record of the wind conditions and your corresponding decisions can be invaluable. It provides objective evidence of the meteorological factors influencing your choices, supporting accountability and transparency.

This record is particularly useful when questions arise about delayed moves or the allocation of resources. It allows you to review past conditions, compare forecasts with actual observations, and demonstrate that your decisions were based on the best available information at the time. This historical data can also contribute to refining your operational procedures and understanding local wind patterns better.

Ireland's coastal waters, particularly on the Atlantic side, are exposed to significant wind events, especially during the storm season from October to March. This seasonality means that wind conditions can be highly variable and rapidly changing, posing frequent challenges for marine pilots and tug operators.

Each port authority in Ireland manages its own pilotage services, with specific rules and guidelines that account for local conditions. While Met Éireann provides national weather forecasts, localised wind data at critical operational points, such as pilot boarding grounds, is essential for your work. The instrument provides this specific local data, interpolated to your working height of 10 metres.

Understanding the P(above your limit) from ensemble members helps you navigate the often-turbulent Irish weather. By focusing on the likelihood of exceeding your operational thresholds, you can make informed decisions that account for the unique meteorological challenges of Irish waters, ensuring the efficiency of vessel movements.