Having live current speed and heading data is critical to the success of any tidal turbine installation where subsea operations are limited to extremely narrow windows. Until now the only way to obtain accurate, live data has been to deploy a separate work vessel equipped with current monitoring equipment wasting fuel, time and money.
Mojo Maritime have developed a highly stable current monitoring buoy that is capable of being deployed on sites with extreme current speeds and transmits live current profile and heading data to the installation vessel. The buoy was deployed for the first time in July 2011 at the EMEC site, Orkneys, during the successful installation of a mono-pile for the Voith tidal turbine.
Managing Director of Mojo Maritime Richard Parkinson commented, “Working at the EMEC site is extremely difficult as the tidal current is so unpredictable, some days slack water can be up to an hour ahead or behind predictions and the rapid change of current speed and direction can really upset subsea lifting operations…Having the buoy meant we always had extremely reliable current data so we could make the best use of the working windows and were never caught out when the current decided to rapidly change.”
Conventional buoys are not suitable for use on strong tidal current sites as the drag forces pull the buoy under water when the current speed increases. The Mojo Current Buoy has been designed to be deployed on sites with current speeds up to 9 knots whilst continuously transmitting live data to the receiving station, be it the installation vessel or a nearby shore station.
Jon Csehi, an engineer at Mojo who worked on the design said, “We were extremely pleased with the performance of the buoy and particularly with the quality of the data we received. The catamaran hull and relatively short length of the buoy provided a very stable platform for the ADCP and GPS equipment….We have also just finished some modifications to the buoy which will allow us to add more equipment like motion sensors and MET sensors so that it can be used for wider applications in places where conventional buoys aren’t good enough”.