Piloting Ships in Restricted Visibility
July 1, 2017
Maritime piloting is loosely defined as directing the movement of a ship within pilotage waters. This has traditionally been accomplished by frequently and continuously determining one's position relative to geographical points. Pilots conduct this work mostly "by eye," relying on visual cues (lead marks, points abeam, ranges of convenience, etc.). So what happens when visibility reduces and all visual cues are lost? The answer to this question will vary from one pilotage ground to another and from one pilot to another; however, there are common principles worth exploring.
Navigating ships through confined pilotage waters is inherently riskier than navigating a ship at sea. For this and other reasons, shipmasters typically employ local pilots. Pilots are subject-matter experts and skilled shiphandlers.
As a starting point, we should put the concept of "risk" in perspective. There is risk associated with any ship movement, even during the best conditions. Mariners routinely adopt precautions to maintain risk at a safe level. For example, we employ assist tugs to safely turn and berth a ship in a confined Harbor; we develop and discuss passage plans; we proceed at a speed that is safe considering the prevailing circumstances; and we participate in Vessel Traffic Services (VTS) where available. It is important to appreciate that these routines, and many others like them, do not eliminate risk. Rather they are intended to maintain risk at an acceptable level.
Mariners are also aware that risk can increase when conditions change. For example, risk typically increases when the wind builds, when traffic becomes more congested, or when the waterway becomes more confined. But, as the risk increases, we layer on additional precautions to mitigate the increased risk and maintain it at an acceptable level. For example, a route farther off a lee shore might be chosen during strong winds, additional lookouts might be posted in congested waters, and increasingly frequent position monitoring might be required when navigating confined waterways. It is important to appreciate that these additional precautions do not necessarily return the operation to the exact same level of safety; rather they return the operation to a level of safety that should be roughly equivalent.
This article seeks to slice the onion a little finer by analyzing in greater depth the specific precautions a pilot and master might employ to maintain an "equivalent level of safety" while moving a ship through confined waters during restricted visibility. Our basic assumptions are:
We are moving a large commercial vessel through pilotage waters during very low visibility.
A licensed pilot is employed to direct the vessel's movement.
The vessel is fitted with typical bridge equipment – two marine radars, GPS, ECDIS, AIS, two or more VHF-FM radios, depth sounding equipment, and all the typical ancillary bridge equipment normally fitted on a seagoing merchant vessel.
The pilot has brought aboard a carry-on Portable Piloting Unit (PPU) capable of supplying highly accurate position and predictive information in an electronic display format.
Lower Visibility, Higher Risk
When a pilot loses all visual feedback, he/she typically turns to feedback from electronic sources, such as radar and ECDIS. This is an entirely different type of feedback, and most of us find it more difficult to interpret and use as a basis for navigational decision-making.
The increased risk associated with losing all visual feedback generally falls into the following broad categories:
Decreased navigational control: it is more difficult to keep the ship properly positioned relative to her surroundings, which is the pilot's primary objective.
Elevated workload: it is more demanding to conn the vessel when we can't see, so the pilot's workload is higher than normal. If all else remains the same, any unanticipated workload spikes can overwhelm both the pilot and the bridge team.
Collision avoidance: Although modern radar equipment has greatly improved a mariner's ability to develop reliable information to aid collision avoidance, it is still more difficult to precisely interpret another vessel's speed and direction of movement when we can't see it visually. Moreover, another vessel's sudden course change in the fog might not be recognized immediately.
All these factors, if not mitigated, can combine to elevate risk and to an unacceptable level. So the question becomes, what precautions are needed during restricted visibility to return risk to an acceptable level?
Pre-Planning the Shipmove
Thoroughly pre-planning a restricted visibility shipmove is a good tactic to head off workload spikes before they occur. A threshold issue is to analyze whether an additional pilot might be needed for the shipmove. Involving a second pilot to task-share during the conning activity can be helpful to manage the added navigational and collision avoidance workloads. Also, if the pilot organization has shore-based radar covering the pilot ground, an additional pilot might stand a radar watch to double-check small target detection and provide input as necessary for onboard navigational decision making. Even if a second pilot will not accompany on the shipmove, it is a good idea to involve a second pilot in the planning phase to assist with the risk assessment. This practice is in keeping with long-accepted shipboard practices that require a "second set of eyes" on higher risk activities such as tank entry, hotwork, and working aloft. It provides a good double-check of decision-making, aids the "go/no go" decision, and enhances risk analysis.
The pre-boarding briefing should be utilized to discuss the passage and reach a common understanding regarding how the passage will be conducted. Intended track, speeds along the various parts of the route, minimum horizontal and vertical clearance requirements, wheel-over points, tug placement and utilization should all be discussed. If more than one pilot will be onboard, the briefing should address which pilot will be responsible for the various tasks, such as conning the vessel, VHF radio watch, radar watch, PPU operation, etc.
For inbound vessels, the planning activity should include confirming the wharf or terminal is ready to receive the vessel. This can usually be accomplished by contacting the terminal or the vessel agent. Confirm that the berth is clear – no vessels are moored alongside – and establish a reliable point of contact terminal-side who will be available during the berthing operation. If the terminal has shoreside gantry cranes, verify that all are topped up and positioned in a safe area on the berth – i.e., amidships and away from the location of the bow and stern flare. If berthing during hours of darkness, confirm that the terminal will be lit. Shoreside lighting, in particular a light marking the bridge position, is very helpful when making an approach to berth on a dark, foggy night.
A similar protocol should be employed for departures. Before boarding the vessel, inspect the terminal with particular attention to ahead and astern clearances and whether there are obstructions on the waterside. Check that terminal cranes are topped up and located away from the bow and stern flare.
Speed of Advance
Setting an appropriate speed of advance (SOA) is probably the most important precaution one can take during restricted visibility. Generally, this means reducing speed as visibility becomes more restricted. Aside from the obvious need to comply with the requirements contained in the "Rules of the Road," reducing speed makes it less difficult to keep the ship properly positioned relative to her surroundings. It also protects against workload spikes by slowing everything down and affording more time for information development and decision-making. Lastly, it aids collision avoidance. A good rule-of-thumb for speed reductions is to reduce to at least half the normal speed when heavy fog is encountered. If the normal speed for a certain maneuver (such as negotiating a 50-degree bend in a ship channel) is three knots, then reduce to 1-1/2 knots when performing the same maneuver in zero visibility. In addition to vessel traffic, channel dimensions and environmental factors (current, wind, etc.) must be considered when determining appropriate speed in fog.
Proceeding at a slower speed aids vessel control. As discussed above, a pilot's ability to direct the movement of the vessel degrades when he/she cannot see. For example, many shiphandlers find that they tend to initiate turns late when relying on electronic feedback. It might be difficult to recover from a mistimed turn or some other control-related problem if traveling at one's "normal" SOA. However, when transit speed is halved, everything slows down and precise timing becomes less crucial. If a turn is initiated late (or early), it is much easier to implement a corrective change. In my mind, this is critical when piloting without visual cues, i.e., when using a carry-on PPU in conjunction with other electronic feedback. A slower speed will afford more time for navigational decision-making and will significantly reduce the level of precision required to maneuver a large ship absent visual cues.
Proceeding at a slower speed also serves to mitigate unexpected workload spikes. Almost every piloting-related task is more difficult in RV. Conning the ship, maneuvering assist tugs alongside, picking up tug lines, and ascertaining the movement of other vessels are all more difficult in the fog. In a nutshell, everything is more difficult and takes more time when you can't see. If anything unexpected comes up, the pilot's already elevated workload can quickly become unmanageable. Slowing the ship down is a very easy way to mitigate workload spikes before they occur and avoid becoming overwhelmed. My personal habit is to slow down to the point that the passage becomes boring. That usually means I have enough mental "bandwidth" in reserve to handle any unanticipated events.
One concern with moving a big ship through a Harbor during zero visibility is that it can be difficult to detect small craft on radar. If a small vessel is detected by radar, it can be difficult for a large vessel in a narrow channel to change course to avoid. One approach is to keep your speed low enough (about three knots, which is "walking" speed) to allow the small craft to maneuver out of your way. If I detect on radar what I believe to be a small craft ahead during low visibility, I stop the engine and, if necessary, use my assist tugs to take all way off the ship. A small vessel approaching a large vessel will be able to hear its whistle and see it visibly in sufficient time to take appropriate action. Once the small vessel is clear, I resume my transit. I don't recommend maneuvering a large, slow-moving vessel in a narrow channel to avoid a small vessel. I find that it is usually better to stop the ship and let them maneuver to avoid you, then resume your transit.
Other tactics can be adopted to reduce the risk associated with moving a ship in the fog. The appropriateness of these would vary depending on the pilotage ground, the individual pilot, and the pilot organizational structure. In addition to the tactics discussed above, pilots could consider imposing one-way traffic restrictions in narrow channels when and where appropriate, and employing additional tug assistance above and beyond the minimum clear-weather requirement.
Imposing one-way traffic in a Harbor setting reduces the risk associated with meeting other large vessels in narrow waterways and builds in a greater margin of error by allowing transiting vessels to navigate mid-channel.
Just as the shipboard risk increases in the fog, so does the risk associated with operating assist tugs. Tugs will have more difficulty coming alongside, executing orders, keeping position relative to the ship being assisted, etc. Ship pilots should take this into consideration.
Ship pilots should conduct a briefing with the tug captain at the beginning of the job. Discuss tug placement and intended maneuvers in greater detail than you might otherwise so that the tug captains know what to expect and have an opportunity to voice any concerns they might have. A tug captain might be comfortable working center-lead forward in clear weather, but prefer the shoulder when visibility is low. Also, it is a good habit to encourage tug captains to speak up if they see anything that doesn't look right or if they are having any difficulty whatsoever while operating in the fog. A tug may not be equipped with the most current GPS-based navigation system and the tug captain may not be as comfortable as the pilot when operating in the fog. It is better to understand any limitations unique to RV operations beforehand.
Allow more time for tugs to make their lines fast. When making fast to very large ships in dense fog, the tug captain might have difficulty approaching the ship and seeing the chock locations. A crewmember with a light can be very helpful to guide the tug to the connection point. And, as discussed, reducing speed affords everyone more time to make tugs fast safely.
Rely on the tug captains to be a second set of eyes during the transit. Sometimes they might be able to see under a fog layer when you can't see anything from the wheelhouse, 120 feet above the water. Also, it is likely the forward tug captain might be able to see ahead of the vessel, even when you can't see the bow.
Execute maneuvers, such as turning in a basin, more slowly, taking a step-by-step approach. In good visibility it might be appropriate to enter a turning basin at 3.5 knots, have both tugs start pulling to turn the ship as you are backing the engine to reduce headway, and make a nice 180-degree turn in one fluid movement. But this is not so easily choreographed when you can't see. A good plan in the fog might be to enter the basin with bare steerage way, get the ship completely stopped in the middle of the basin and then use the tugs to turn it around. Using a step-by-step approach to execute maneuvers in the fog makes it easier to maintain control and compensate for positioning discrepancies that can arise when relying solely on electronic feedback.
Lastly, it is never a good idea to overly rely on a single piece of equipment, for example, a carry-on PPU. While a PPU is a great tool to assist with conning the vessel during RV, a pilot should never put him or herself in a position where the failure of that one piece of equipment will jeopardize the transit. By keeping speeds low and using the PPU in conjunction with ship's radar and ECDIS, a pilot should be able to continue effective control of the vessel even if one system fails.
Whether or not to move a ship in the fog is a complex decision. Shipmasters should carefully consider all the factors, including the advice of their pilot before making any decision to proceed. That being said, by employing effective strategies to mitigate the risks associated with restricted visibility, ships can be moved safely in most cases. It goes without saying that pilots must serve their customers and protect the public interest. By developing effective strategies and conducting thorough risk analyses, we should be able to do both, all the while maintaining a level of operational safety that is equivalent to a clear weather shipmove.