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The use of towed arrays consisting of multiple lines brings with it special problems for adaptive beamforming. The large number of elements coupled with array motion results in snapshot deficient situation in which a reduced degree-of-freedom approach is required. The existence of imbalances between arrays, variable ocean currents and towing dynamics cause distortion in array shape which may be unknown or poorly known. One of the advantages of adaptive beamforming is its ability to overcome left-right ambiguity that results from the conical beampatterns of the individual lines. We examine approaches that first perform conventional beamforming on individual lines followed by adaptive combination of beam outputs across lines. Three approaches to array shape estimation for adaptive beam-combination are examined. The first assumes element positions are known to some accuracy and uses that information. The second assumes no shape information and uses self-cohering on a source of opportunity. The third uses self-cohering to align the beams of different lines and then uses position information about one reference element on each line. The effectiveness of these approaches is examined using simulations for various amounts of array distortion.