Tony Trapp's ingenious 'whale tail' generators seem to have a major disadvantage in their production of 'bumpy' electricity. With the terrawatts of available energy the loss of a little through inefficiency would not matter, so perhaps an alternative sea-bed generator based on the vertical axis Savonius (oil drum windmill) principle could be used.
Such units, of similar size to the Stingray could be constructed and towed to site on concrete caissons which when sunk and ballasted would merely then only require electrical connection.
Maintenance might however be a major problem.
A Savonius type wind generator does not have to be pointed into the wind and a marine version would thus cope with directional variations in tidal currents. The power output would be available at the base of the unit, but at a very low rate of revolution, too low for electricity generation.
Perhaps for marine use, Mr.
Trapp's Stingray hydraulics could be used to overcome this difficulty.
Peter Wolley (M), Old Barn, Mill Lane, Leintwardine, Craven Arms, Shropshire.