Monitoring for Efficiency, Safety

Ferry masters operating off the west coast of Scotland traditionally would have to sail to a port and on arrival visually assess the weather and tide conditions before deciding whether it was safe to berth alongside the pier or quayside: a process which wasted time and fuel, and frustrating the paying passengers.  The berthing of ferries is a high skill job, particularly during bad weather, and the decision on whether a specific ferry can safely berth at a specific port is subjective and ultimately can only be taken by the ferry Master, and includes considerations of not only those onboard, but shoreside personnel aiding with mooring operations.
With multiple sites in island locations, remote access to accurate local data providing live information on tide level and key climatic conditions could facilitate substantial improvements to the service by aiding the Masters to make a more informed decision at an earlier stage in the voyage – in some instances even before departing the previous port or harbor.
Caledonian Maritime Assets Limited (CMAL), which owns many of the ferries, ports and harbors in the region, procured a network of 15 tide and weather stations from OTT Hydrometry. The new monitoring equipment provides live data on port conditions to enable the ferry sailing decisions to be made in a timely manner.
“OTT installed the first monitoring station in August 2014 and the network is now almost complete with sensors providing data every 1 minute via UHF radio to ‘gateways’ in the ferry offices, which then submit the data via the internet to a central  server, which can be remotely accessed by authorized users,” said David McHardie, CMAL Harbor Master. “We have a regulatory requirement to monitor the tide level in our statutory harbors, but this system also provides essential weather information for our ports. In the past, these measurements were taken manually, so the availability of continuous multiparameter data is an enormous improvement – not just in the quality and value of the information, but also in the safety benefits for harbor operations staff, that this provides.”

Live Data
The availability of live data on port conditions theoretically enables the ferry Masters to make better informed decisions at an earlier stage, potentially  saving time, fuel and costs. Emphasizing the growing need for data, McHardie said: “In recent years, severe weather events appear to have become more frequent and they seem to develop faster; for example, since the monitoring network was installed, we have recorded a sudden drop in temperature of 8°C in just 5 minutes at the port of Armadale on the Isle of Skye, and a maximum wind gust of 96 knots at Castlebay on the Isle of Barra. These conditions represent a rapid deterioration of conditions and the monitoring network enables us to respond quickly and effectively.”
Each monitor is located adjacent to the main berthing area on the pier with a lockable GRP control box. The system is comprised of: an OTT radar level sensor; a Lüfft ultrasonic weather monitor measuring wind speed, gust and direction, air temperature and barometric pressure; an Adcon radio unit with back-up batteries and a marine grade antenna. The radar tide level sensor is an OTT RLS, a non-contact sensor employing pulse radar technology with a large 35m measurement range.
Both the RLS and the weather sensors, which have no moving parts, have extremely low power consumption, which is vitally important for installations at remote sites. At two locations it was not possible to install a radar sensor so an OTT CBS (bubbler sensor) was installed providing comparable levels of accuracy and reliability.
Now that the CMAL monitoring system is installed, McHardie is looking for ways to leverage the value of the data. For example, radio data transmission works well over water, so it should be possible to fit the same technology on ferries so that the ferry Masters can access the data directly, instead of having to call the port office for a verbal update. The OTT monitoring network also incorporates an email alert system, and whilst this has not yet been configured, it will be possible in the future for ferry masters to receive email alerts warning them when pre-specified port conditions arise.
“We would also like to eventually make the data available to the public as part of an enhanced harbors information system,” McHardie said. “However, when a ferry has berthed, with the monitoring system being located on the pier, the vessel can cause a wind shadow; which means the wind data during that period can be potentially misleading. It has to be remembered that this system remains only an aid to navigation.”


(As published in the September 2015 edition of Maritime Reporter & Engineering News - http://magazines.marinelink.com/Magazines/MaritimeReporter)