Single point mooring buoy monitoring

Paul Boughton

Sandy Thomas reports on the installation and commissioning of a single point mooring buoy for Khalifa Point in Pakistan.

Force, strain and load measuring systems are used in oil and gas industries, both on and off-shore. These systems range from high performance load cells to custom designed, fully integrated, multi-sensor packages that monitor vessel draft and ballast, metocean conditions, vessel loading and structural dynamics.

A recent project that Strainstall has installed and commissioned is for a single point mooring buoy for Khalifa Point in Pakistan.

The buoy has been refurbished having been previously deployed in the Middle East, and in order to comply with Bureau Veritas rules, a hawser load monitoring system, together with a package of navigation aids and control/communication systems, was required.

Strainstall designed, built, tested and commissioned an integrated system which was approved by Bureau Veritas.

The system uses load pins incorporated into the mooring bridle to provide a continuous real-time monitoring of loads in the hawser, and is designed to protect the mooring equipment by ensuring it is not overloaded and in danger of breaking the hawsers and allowing the tanker to drift. This is particularly vital during oil transfer operations due to the increased risk of oil spillage.

Data logging system

The scope of supply for the buoy included a Strainstall dual bridged load measuring pin (with a design life of 25 years plus), Strainstall Intrinsically Safe line amplifiers to condition the signals from the load pin, and a PLC-based data logging system. Communication of data to the ship is via AIS Aid to Navigation (AtoN) transponder that provides the additional benefit of buoy location and identification to local shipping.

Remote control and back-up data monitoring is available using a GSM communication module through SMS messaging. In addition to the AIS Transponder the navigation aids package is completed by a 5nm LED navigation light and a 0.5 mile fog horn.

The primary channel for reception of buoy data at the offloading tanker is through the vessel's Class A AIS transponder, via the pilot port, to a receiving module that retransmits the data to any web enabled display. In this case a Netbook computer was supplied, however, any browser based device with WiFi can be used. Should there be a problem with the vessels pilot port, an AIS receiver is also supplied as part of the carry on equipment that is housed in a compact backpack.

In addition to hawser load, the battery voltage, fog horn and navigation light status are also displayed to provide the Mooring Master with real time information, and there are also alarm notifications in the event that any predefined parameters are exceeded.

The foghorn can be controlled from the display or by SMS text message from any authorised mobile phone.

All equipment supplied for the buoy has been designed to withstand use in harsh marine environments and is certified for use in Zone II Hazardous Areas, with the added benefit of being powered by a solar charged battery pack for long-term, maintenance free operation.

Enter √ at

Sandy Thomas is Marine Director, Strainstall UK Ltd, Cowes, Isle of Wight, UK.

Recent Issues