Apparatus and methods to operationally link (couple/decouple) a plurality of relatively massive, complimentary payload platforms (i.e., suspended machinery and ROV) at relatively deep working depths in an unstable marine environment (water column) while the payload platforms are in-transit. An apparatus includes a suspended machinery, an ROV, a capture collar, an extendable/retractable harpoon, and actuating machinery to controllably effect extension and retraction thereof. A method includes providing an in-transit suspended machinery having a capture collar, providing an in-transit ROV having an extendable/retractable harpoon, approaching the in-transit suspended machinery with the ROV, maneuvering the ROV so as to bring an end of the partially extended harpoon into aligned proximity with the capture collar, and further extending the harpoon so that it securely engages the capture collar.