Subsea 7 has placed an order for 21 of Sonardyne International’s new Compatt 5 Max subsea positioning transponder for use in BP’s Skarv field offshore Norway.

The Max transponder has been introduced by Sonardyne to meet operator’s needs for a semi-permanent seabed transponder that can be utilised for life-of-field subsea positioning tasks. An ultra long battery life enables Compatt 5 Max transponders to be left in-situ throughout all drilling, production and construction activities. It is expected that this will produce valuable cost savings for field operators by minimising the vessel deployment costs typically associated with installing, recovering and then re-installing seabed transponders for each positioning task.

The Compatt 5 Max transponders delivered to Subsea 7 will be deployed this summer (2009) in the Skarv field which is the largest current ongoing field development offshore Norway. Their first task is to provide precise positioning for the installation of various subsea templates in water depths ranging from 350 to 450 metres. With the transponders left deployed, the units will be available at any time for other tasks including metrology, cut-to-length and umbilical lay.

Fitted with lithium batteries, the new transponder has been calculated to offer a working life of two years of continuous operation for subsea navigation and data telemetry functions. This is substantially longer than conventional seabed transponders however real-life predictions, taking account of periods of inactivity, suggest the Max’s battery life to be three years.

In addition to a long operating life, a Compatt 5 Max transponder provides all the benefits of Sonardyne’s Wideband signal technology for multi-vessel and subsea vehicle positioning. A network of Compatt 5 Max transponders can therefore be used to provide DP and survey references for different vessels undertaking different tasks simultaneously. This applies to vessels equipped with both Sonardyne and non-Sonardyne systems such as Kongsberg’s HiPAP®.

A range of integrated sensors is available with the Compatt 5 Max. These include sound velocity sensors which are fitted as standard and permit positioning to be corrected for local variations in sound speed through the water column. Subsea 7 is has ordered all omni-directional transponders although directional transducers are also available for deep water deployment in water depths up to 5,000 metres.