A foil having a leading edge, trailing edge, chord and span is attached between a first head float position and bottom submerged position below the head float on the array. The foil being flexible along its span and has a first interior conduit rearward of the leading edge and a second interior conduit forward of the trailing edge. The conduits are centered on the chord and separated by a distance. A first cable having a first length is strung inside the first conduit and a second cable having a second length is strung inside the second conduit, and an adjustment mechanism is used to vary the length of the first cable relative to the length of the second cable and vice versa.