Safe Anchorages — A Mariner’s Perspective

15 Июл

Статья посвящена вопросам, связанным с безопасной якорной стоянкой. В частности, рассматриваются следующие аспекты безопасности якорной стоянки: глубина вод, грунт на якорном месте, подводные препятствия. Особое внимание уделяется условиям устройства безопасной якорной стоянки, а именно: достаточная просторность, хорошая связь и портовые услуги, контроль и инструктаж со стороны портовых властей, а также информированность капитанов судов о ситуации на рейде. Публикация особенно интересна рекомендациями, которые дает автор по организации безопасной якорной стоянки, и описанием случаев из практики.

It is often taken for granted that every port will have a suitable anchorage where vessels can anchor and await entry. But what does a ‘safe’ anchorage really mean to the mariner?

What is a safe anchorage? Quite simply, as one ship’s Master recently described it to me, ‘It is a place where I can anchor my ship and feel safe’. That feeling of safety comes from many factors, but it is strongly influenced by the Master’s knowledge and experience. Nevertheless, there are features that provide us with the confidence that we can bring our ships and remain there, sometimes for a substantial amount of time and then depart safely. Conversely, there are anchorages that we would rather avoid if at all possible.

As many of us have seen, an incident in an anchorage can have a catastrophic effect not only on the vessels involved and those that man them, but on the environment and the whole port infrastructure. Unfortunately, the number of accidents in anchorages is increasing worldwide. So, what makes the difference — and what can Harbour Masters do to make anchorages in their ports as safe as possible?

What makes аn anchorage safe?

Depth of water

The minimum under keel clearance for a vessel to proceed in a narrow channel or fairway, is usually considered to be about 10% of the draught of that vessel. In an anchorage, a mariner will be looking for substantially more than that, as the vessel is unlikely to sit well at anchor with such minimum clearance, especially if there is a strong current or wind. Too much water can also be a problem. In my experience, a prudent Master will not try to anchor in more than about 80 metres of water, as the windlass is unlikely to be able to lift the weight of the chain and anchor off the seabed unless it has been specially designed for the task.

Holding ground

A good holding ground is essential to make an anchorage safe. Mud or sand are fine. The anchor is designed to dig in to these mediums with the weight of the chain laying on the sea bed holding the anchor in place, preventing it from being lifted out as the vessel swings around. An anchor holds best when the cable pulls horizontally on the anchor flukes. ‘A pull of 5° above the horizontal is considered to reduce the anchor power by 25% and 15° to reduce it by 50%.’ Spencer C. (2008).

Obstructions

Rocks make for a poor holding ground, with the additional risk of the anchor becoming trapped and possibly irretrievable. Vessels do lose their anchors, perhaps more frequently than you may think. According to the Swedish Club ‘Around half of all vessels will lose an anchor at sometime during their lifetime.’ (2000). When they do so within an anchorage, that anchor and chain then becomes an obstruction.

Some anchorages have a substantial number of obstructions, both natural and manmade, which makes anchoring vessels very difficult and at times dangerous. Imagine you are on a ship at anchor and a storm is bearing down on you. You decide it is time to heave anchor and proceed out to sea to weather the storm away from land, only to find that you cannot lift the anchor as it is stuck on an underwater obstruction. Your only option is to slip the anchor and chain leaving it there, thus creating yet another obstruction!

In a relatively new port, the anchorage may have been positioned by design, but historically, most anchorages have just evolved as the most suitable place for a Master to anchor his vessel near to the port. As the port expands, so the amount of space required for anchoring vessels will also increase. However, the space available to do so may be finite. This can lead to congestion with an associated increase in risk to the vessels, environment and port infrastructure.

The amount of space available is an important factor when considering whether an anchorage is safe. Firstly, is there enough space to make a safe approach to the chosen or designated spot?

Once at anchor, is there enough room to be able to swing around the anchor having deployed sufficient chain to hold in the most adverse environmental conditions expected? Traditionally the length of the anchor cable is measured in shackles (or shots in the US) where one shackle equals 27.4 metres. The formula 1.5VD (where D=Depth of water in metres) gives the minimum number of shackles that should be used.

I normally anchor my vessels in about 30 metres of water and use a minimum of 240 metres of anchor chain, in good weather. The length of the vessel is normally 333 metres, a standard VLCC, so my potential anchor swing circle has a radius of roughly 500 metres.

In a crowded anchorage we do not have the luxury of a swing circle diameter of 1 kilometre, so we have to put out less chain and hope that it is sufficient to hold our vessel. We also have to bear in mind that all vessels do not behave in the same way. While it is logical to think that vessels in an anchorage will all point in the same direction, that does not aKvays happen, especially in anchorages prone to squalls, local winds or variable currents. We can end up stern to stem with another vessel, as h appened recently following a brief but strong line squall.

An associated issue is the other activity that may be taking place within the anchorage. Sometimes fish are attracted to anchorages, and are followed by a number of fishing boats. When a fishing boat is on the fish, they are extremely reluctant to move for the large vessel bearing down on them and trying to anchor in ‘their’ spot.

In addition to fishing boats, crew changes and deliveries may require a number of small boats going to and from the anchorages. Some anchorages are well know’n for numerous small vessels trying to board the anchored ships by any means possible so that they can trade their wares.

Vessel movements are yet another issue: I have seen vessels transit through the anchorage, leading to a significant amount of congestion and, at times, navigational chaos. It is not unusual to see vessels or other craft, barges, cranes, etc. under tow in anchorages. All these vessels need their space, but wherever possible they should be kept separate from anchored vessels.

Commynications and services

Other considerations that make an anchorage safe are:

— Local w’eather information available and broadcast at regular intervals;

— Shelter from wind and current, and preferably not on a lee shore;

— Effective communications with the shore authorities;

— Good cell phone coverage;

— Security patrols.

I would like to emphasise the importance of security patrols. Throughout my career deep-sea in the 1980s, we were subject to intermittent boarding by thieves in various ports, intent on stealing what they could. I can only remember one occasion when we actually considered them pirates, and even then we did not take it too seriously.

That was 30 years ago. How times have changed. Piracy is a major threat to merchant ships and the mariners onboard them. We hear almost daily of vessels being boarded and mariners being captured, killed or just disappearing. According to IMO statistics available at www.imo.org in November 2013 there were ‘26 reports of acts of piracy and armed robbery’ against ships. Of those 26 attacks, 16 occurred on vessels at anchor’. (2014).

Harbour cortrol and direction

One of the main differences between anchorages is between those w’hich are controlled, and those which are ‘open uncontrolled’. Even in controlled harbours, it is not always clear who is giving directions. The controller is just a voice on the VHF radio. For all the crew on the bridge know, the person giving advice may not be a mariner and may have no experience of manoeuvring large ships, let alone in close proximity’ to other vessels and shallow water.

How far can the mariner rely on the quality of information they are being given in these circumstances? Further, what should the Master do if he is not in agreement with the advice he is being given? Refusing to anchor the ship in accordance with the instructions given may lead to the vessel losing its place in the queue for the berth, and put the company in breach of a charterparty.

Of course no responsible Master will knowingly put his ship in immediate danger. How’ever, I know of occasions where accidents have happened to vessels where the Master was not 100% comfortable with the advice being given, but felt he had no choice but to comply. For example, a Master of a fully loaded bulk carrier was proceeding down a fast flowing river when the Captain of the Port ordered him to stop and go to anchor in order to investigate an incident which had occurred to the vessel previously. The pilot onboard advised the Master to anchor the vessel nearby. The Master was not happy with this position and questioned its suitability’ with the pilot, only to be assured that vessels anchored there all the time and it was the Port Captain’s instructions. The pilot disembarked. A few hours later, the vessel dragged anchor and grounded, causing hull damage so severe that the crew’ had to fully discharge the cargo prior to leaving the river and then proceed to dry dock in ballast for repair.

Need to know

Consider for a moment a Master approaching a port for the first time. This is their first voyage as Master and naturally they are a little nervous and want to get as much information as they can about the port and its associated anchorage. Onboard, the Master is able to consult the sailing directions, the Master’s Guide to Port Entry and the chart. There is no access to the internet to do any research; the Master is only able to send and receive e-mail. Perhaps surprisingly, this is not an uncommon scenario.

What information should the Harbour Master pass to that Master regarding the anchorage? And, just as importantly, how much can the Master rely on that information? For example, would it be better to provide the local weather forecast so that the Master can make an informed decision about how much anchor chain to use, rather than just basing the length of chain as a function of depth of water?

Is the anchoring position suitable for the vessel’s length, draught and duration of stay? Ideally, the Harbour Master would tell the Master the approximate time until berthing and give the vessel a firm place in the queue so that the vessel can wait further out to sea away from the majority of other vessels, if the Master chooses.

Incidents

Unfortunately, the number of accidents in anchorages has increased in recent years. In a past edition of their industry magazine Signals, North P&I Club expressed concern that ‘an increasing number of claims are being notified from vessels at the overcrowded anchorages at the world’s maritime crossroads. However, while the claims are clearly linked to congestion, there also appears to be a lack of familiarity with anchoring techniques and uncertainty over the rules governing the conduct of vessels at anchor.’

I  believe that an underlying cause of many marine accidents and incidents onboard today’s vessels is a lack of experiential knowledge, which is not being transferred from senior to junior officers by mentoring. According to Steve Trautman in his book Teach Whaf You Know (2007) ‘Up to 70% of skill is leamt from experience’. It is this maritime skill pool that I believe is not being passed on by mentoring.

Looking specifically at accidents in anchorages, on many ships these days it is a company requirement that the senior officer (the chief officer) is forward on the forecastle for letting go the anchor. In my opinion, this is completely wrong. The second and third officer should both be trained in how to let go the anchor. The chief officer should be on the bridge with the Master, learning how to anchor the ship before he takes command and has to do it by himself.

What the Harbour Master саn do

The training and mentoring of officers is an issue that the maritime industry must address at every’ level, and The Nautical Institute is working hard to promote the introduction or re-introduction of mentoring onboard. However, Harbour Masters also need to take a close look at their own part of the industry, to see if there is action which they could take to improve the situation in their anchorages and ensure that mariners feel safe anchoring their ships there.

There is not much that can be done regarding the physical location of the anchorage (unless it is a new port), the depth of the water (although it may be possible to keep an area prone to silting dredged) or the shelter afforded to the vessels at anchor. However, there are several steps that can, and should be taken:

— Ensure that the anchorage is as clear as possible of obstructions. When a vessel reports that they have come upon an obstruction, the Harbour Master should determine the location and nature of the obstruction. If the obstruction cannot be removed, vessels should be told that it is there so they can avoid it. It is important to have an up-to-date survey of the anchorage giving accurate depths and foul areas, and that this information is published on the charts and in port information resources, including online.

— Pass on as much information as you can to the approaching vessels in a timely manner, so that they can make informed decisions.

Make sure that information, advice and instructions are correct and appropriate for that individual vessel.

— Consider the needs of the first-voyage Master, and provide every vessel approaching the port with the same information. I cannot imagine even the most experienced Master complaining that he is being provided with too much information (see box below for an example of what happens when crucial information is missing).

— Keep the anchorage as clear as possible of other vessels. It may be possible to design a system of safety fairways that vessels can use when approaching to and from the anchorage, when proceeding directly into the port, or when just transiting through the area. Many of the ports off the Texas coast where I work have this system and it is effective.

— Give thought to the mariners that are onboard the ships in your anchorage and do all you can to help them feel safe. Try and keep the vessels secure.

Some of these suggestions will have financial implications, but the anchorage is just as vital a part of the port infrastructure as the berths, and should be viewed accordingly.

Developing mentoring

Finally, I hope that ships’ crews, pilots and Harbour Masters will all join the ongoing conversation about mentoring. I do not believe that it is just the shipping industry that is suffering from the demise of this informal style of training. Whatever your position, please take a few moments out of your busy schedules to pass on some of your experiential knowledge. I personally believe that, as masters of our various trades, we have a duty to pass on our knowledge through mentoring (or whatever you want to call it), and to put something back into the community that has given us so much.

Need for mentoring and information

A laden bulk carrier of about 9.5 metres draught was approaching a port anchorage to anchor and await a berth in a nearby port. The coast line ran north/south and the anchorage was only about 1.5 miles to the east of the coast. The wind was north easterly at about 30 knots and the current was NE going at about 2.5 knots. The first-time Master was on the bridge and had the conn, the vessel was in hand steering with a competent helmsman and the second officer was in the chartroom putting positions on the chart by GPS as directed by the Master. The chief officer was forward ready to let the anchor go when instructed by the Master.

As they approached the anchorage, the Master swung the vessel to the wind across the current as he expected the wind to be the dominant environmental force on his vessel. It wasn’t. The current set them rapidly ashore with resulting significant damage to the hull of the vessel and to the coral reef which they grounded on.

The vessel was refloated the following day and taken to anchor for damage assessment. There was significant hull damage but the propeller and rudder appeared to be in good condition, so it was decided to conduct sea trials prior to port entry. Having completed the trial, the vessel steamed back toward the anchorage, where the environmental conditions were much the same as they had been two nights ago, when the vessel went aground. It soon became readily apparent that the Master was going to take exactly the same approach as before — which would have led to exactly the same result. Luckily, one of the consultants onboard realised this and quietly advised the Master on how to anchor correctly in these conditions.

I believe lack of experiential knowledge was a root cause of this incident. Had the first-voyage Master been given information regarding the strength of the current, the outcome may have been different.

Автор:

Captain Andre L Le Goubin

MNM MA FNI

Mooring Master & STS Superintendent — AET Inc. Ltd.

Источник:

Seaways. — 2014. — June. — P. 8 — 10.