The next convoy, UGS 54 to Plymouth, England, in September, was uneventful until "Underhill" left Plymouth in October. Upon leaving the harbor, a submarine sonar contact was made in the English Channel. Several hours of depth charging accomplished nothing, but while running the patterns, the ship struck an underwater object (possibly a U-boat) destroying the ship's sonar soundhead. "Underhill" drydocked at Plymouth, but the British were unable to make needed repairs, so "Underhill" returned to Boston with a group of tank landing ships (LSTs) for a new sound head.