Maintenance

Many marine schemes fail because they are either impractical, or uneconomic, to maintain. In the SST 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 has 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.

Positioning the SST for maintenance is the reversal of the second stage of installation:

From its stopped position, water is pumped out of the main body spar buoy tanks ....

The turbine rises in the water and as it does so, starts to roll ....

... until it reaches a stable position on the surface of the sea ....

In its maintenance position, the SST body - hinged as it is to the seabed and with considerable length - will be stable. Access for maintenance will present the same issues as to a fixed platform, for instance an offshore oil rig. Once 'on board' the SST, maintenance staff can gain access to the electrical /control room (left hand end in the image above) and each machinery pod via hatchways and cross arms. Blade access and hub access can be gained by temporary platforms slung under the cross arms.

Access to the seabed hinge would be by hoisting up the swing-arm in reversal of the installation process, though the hinge would be designed for a very long life so as to make this an unlikely event.