SHOULD THE TURBINE BE LOCATED AT THE SURFACE OR ON THE SEA FLOOR ?

Where it is possible, it is better to use a floatting current converter, whith a turbine just below the surface.

Why?

By looking at this picture, you immediatly know where to settle the current converter

Good to know:

A 15% current velocity loss results in a 50% power loss. (calculation made for a 2,3 m/s current velocity)

The reason is quite simple: in the power formula the current velocity has a cubic factor:

P=1/2 d Cp S V³