RedactedNarrative: Unit 1 was leaving the nearby wake zone. While gaining speed, Unit 1 struck Unit 2. Unit 1 operator advised that they did not see any visible lights on Unit 2 and did not see Unit 2. Witness on Unit 1 confirmed the same. Unit 2 did not have a properly working all around white light and the green navigation light was obstructed. This caused Unit 2 to not be visible to Unit 1.