Many marine schemes fail because they are impractical or uneconomic to maintain. In the Triton scheme, ease of maintenance has been one of the key drivers for the whole design concept. Hinged from the seabed in its maintenance position (see image below), the SST is in effect a tethered catamaran with considerable stability as a platform for access and effective work. Most maintenance work is routine inspection and the replacement of consumables, but if major components need replacing the multi-rotor design means that piece-sizes are relatively easy to handle.

The Pentland Firth is still one of the most hostile regions of water anywhere, and winter storms would restrict major work to the summer months. In its maintenance position, the 1100 tonne SST twin hull body - hinged as it is to the seabed and with considerable length - will be highly stable. Access can be effected by ‘Walk to Work’ gangways from the service vessel, see below. Once 'on board' the SST, maintenance staff can gain access to the electrical /control room (left hand end in the image below) and each machinery pod via hatchways and cross arms. Access to the seabed hinge would be by hoisting up the swing-arm in reversal of the initial deployment routine.

One task that will be inevitable is to de-foul rotor blades to ensure performance does not degrade too far. Colonisation of surfaces by macroalgae, diatoms, and hydroids will take place and will reduce the hydrodynamic efficiency of the turbine surfaces. It will also lead to large encrustations of operating mechanisms, access panels and mooring systems. If not left too long, these growths can be removed by high pressure washing once or twice a year with the rotors brought to the surface as shown above.

A device installed at Race Rocks by Pearson College in Vancouver suffered significant fouling after about 6 months deployment. For example, the picture on the right shows significant fouling of blading.

The water temperatures at that site are similar to those found around the UK including Scotland, so it can be assumed fouling would occur at a similar rate.
 

Maintenance

TRITON

The most powerful tidal current energy generator now in development - 10MW from a single installation

TidalStream have now completed successful testing of a six-rotor scale prototype of Triton demonstrating its versatility, stability, and opportunities for easy access and maintenance