When and why pilots use a PPU
PPU are becoming increasingly important
When it comes to rules on navigation safety there is no official obligation for pilots to use a PPU. The IMO (International Maritime Organization) sole hint to its usage can be interpreted in the Convention on the International Regulations for Preventing Collisions at Sea, 1972 (COLREGs)both in Rule 5 (Look-out):
“Every vessel shall at all times maintain a proper look-out by sight and hearing as well as by all available means appropriate in the prevailing circumstances and conditions so as to make a full appraisal of the situation and or the risk of collision.”
And in Rule 7 (Risk of collision):
“(a) Every vessel shall use all available means appropriate to the prevailing circumstances and conditions to determine if risk of collision exists. If there is any doubt such risk shall be deemed to exist.”
The term “by all available means appropriate” is where we can assume that a PPU is a good candidate to minimize risk.
These rules, last edited more than 10 years ago, clearly focus on making sure that conventional equipment is properly working such as radar technology.
“(b) Proper use shall be made of radar equipment if fitted and operational, including long-range scanning to obtain early warning of risk of collision and radar plotting or equivalent systematic observations of detected objects.
(c) Assumptions shall not be made on the basis of scanty information, especially scanty radar information.”
As we witness a huge increase both in the size of the modern vessels and in their traffic in busy harbors and seaways. Pilots tend to minimize some risk factors by means of more modern tools providing insightful situation awareness information to make a full appraisal of the risk of collision. Proper look-out is definitely better off with additional modern navigation aid tools such as a PPU.
In this article, we will discuss 7 most important situations when a PPU is useful.
A PPU is a great piloting aid system in conditions of limited visibility. Traditional look out can be hard due to the huge size of modern vessels, furthermore, in circumstances when large structures block the sight (i.e. a high stack of containers) the job of the pilot can become quite stressful. The problem becomes more noticeable at night or when extreme meteorological conditions such as thick fog or heavy rain, reduce visibility. In extreme conditions, a PPU sensor can also be considered as an excellent navigation tool.
Bathymetry and cartography does change. As the size and the weight of modern vessels goes increasingly up, the need for accurate and up-to-date charts becomes a key factor. There can be situations when notably, the ECDIS or the printed charts cannot be trusted completely. Pilots can bring accurate charts provided to them by specialized local authorities, but they need to plot onto them, their vessel in real time. The most common method is to plug their tablet to the AIS plug, making this the most basic form of Portable Pilot Unit, in this way they can at least be detached by ECDIS. In situation when extreme accuracy is necessary, other types of navigation sensors can also be brought onboard, but, in any case, the main objective of using their own chart is achieved, and this is very important.
Precise SOG, POS, HDG and ROT
For most of the reasons discussed in this article, pilots are in demand of berthing aid tools that provide accurate vessel location and speed in real-time. Accurate heading information can be determined in several ways. The ROT is equally important. For a deeper analysis on this topic, it is strongly advised that you read the articles on how to determine vessel ROT and accurate heading as well as the article on vessel position and speed accuracy.
The main characteristics of a PPU is to deliver accurate navigation information to provide pilots with sufficient aid to do their job better, safer and with less stress. There are several ways to provide the accuracy required. For more information on these differences, please see the article: the choice of a PPU depends on several factors.
Navigating very heavy/large vessels
When the weight of a vessel is so big that she makes very little headway, the forces which must be applied are massive. This has an impact both on the fuel consumption but also on the attention which goes to applying thrust in a way that is optimal. Generally, this type of operations take a long time and are performed very slowly to reduce risks but also to control the huge amount of power applied. If a very heavy ship accelerates more than expected the predicted position must be calculated sufficiently ahead of time to control her motion. Detecting with accuracy these types of acceleration requires sensors which evaluate the situation very often, and amongst all, with extreme accuracy (1cm/sec), in this case a PPU is the answer.
When it comes to long and large vessels, brings yet another difficulty, to control the drift both on the stern and on the bow and to evaluate the ROT with extreme accuracy. Imagine a vessel which boasts a length of 350m whose ROT is not accurately monitored. It is unthinkable. The water space needed for maneuvering must be enormous, and unfortunately, in some cases, a pilot must assist the commander in tight water spaces.
In tight water spaces
Even in cases when ships are not over 300m in length, it is not uncommon to have vessels with beams over 30m. The size of vessels in the last decade has rocketed up. On the other hand, harbors, canals, rivers, locks have not been able to grow adequately. Despite intensive dredging, building new and larger harbors, today, it is not uncommon that a huge ship must enter a water space with a margin of a few meters. And if this was not a problem big enough, the traffic has also gone up, so the space available needs to be shared. The need to control is never been so crucial as never. This is also why the usage PPU has taken off in the last few years.
For real-time dynamic under keel clearance
So far in this article, we have not touched upon another huge issue, probably the biggest of all: UKC. Depth limits are above all a commercial handicap for shipping companies. On the section of the Elbe river before Hamburg, vessels with a combined beam of more than 90 meters cannot meet in the navigation channel. Access to some ports is limited in small time windows and is dictated by the tide. In some cases, commanders must take the risk to navigate in circumstances where the UCK is at the limit. To achieve this, they must have and excellent control of the position of the ship, the bathymetry must be accurate, the meteocean information must be in real time, the areas with restricted access must be clearly marked. A PPU plugs itself in this scientific environment as a technological tool which acts as a precision sensor of position both on the horizontal plane but also on the vertical axis. Some have inertial sensors which measure the heave of the ship, and the pitch, which in some cases helps detecting the SQUAT effect.
For training and in case of emergency
Some software allows saving and replaying manoeuvres. This is an excellent way to train less experienced pilots. At the same time, more experienced pilots, can learn new ways, once they have been recorded by others.
In the unfortunate event when a complicated situation starts developing, pilots can ask for support to other peers who are more experienced with the problem. Some navigation software, which works in combination with PPU sensors, have a solution for broadcasting in real time on the internet, what is seen on the screen of the pilots on board. Any pilots, even off duty, can be alerted. They can connect to the server using their smartphone and they can see what is going on, in this way they can make a quick precise assessment of the situation and provide support remotely.