Logical way to account for tidal range is to shorten the tether....

Logical way to account for tidal range is to shorten the tether. Now that isn't possible as such but under the buoy or in the buoy it would be relatively simple engineering to have a 5 m hydraulic cylinder between the tether and the buoy that retracts on low tide or extends at high tide so the buoy is always in the highest energy zone. Could also be used to get the buoy deeper in the water in storm events and as a over tension release, releasing shock load to stop wear damage on tethers and buoy. All just a assumption as apart from changing buoyancy of buoy and angle of attach in tidal flow I haven't had any other viable thoughts . Will be interesting if they have another solution.