Tether for submerged moving vehicle

A tether for connecting a moving stream-driven device submerged in liquid to a fixed support structure arranged at a seabed, which tether extends in a main direction (MD) and where the tether comprises a plurality of separate tether portions which are connected together to form the whole tether, wherein the tether portions of the tether comprise,

• an outer shape having a leading edge and a trailing edge, each edge extending in the main direction,
• at least one tensile force bearing portion extending in the main direction of the tether, and
• power cables that are separate from the tensile force bearing portion and are configured to distribute electrical energy generated by the stream-driven device to an electric grid,
• wherein the tether portions are arranged to strive to self-align in relation to a relative flow direction of the liquid, by rotating around a rotational axis that is located in the tensile force bearing portion and is essentially parallel with the main direction of the tether when the tether portions are moving through the liquid, and where the tether is configured to allow for twisting at least partly at different tether portions along the main direction in order to self-align locally,
• wherein at least some of the tether portions are connected at portions thereof other than the tensile force bearing portion, and
• wherein the tether comprises a support structure end portion extending in the main direction and attached to the support structure, and a chord length of the tether increases in a direction towards the support structure end portion of the tether so that the chord length increases toward the seabed.