I just ran across this very old thread, but will say that the LCM-3 is being raised out of the river, vs. being launched.
1) You can notice a "wet waterlin" in the bow area that was most recently in the water.
2) If it was being lowered, the crane would be rotated toward the river, which might prevent the hull from scraping on the stone embankment.
3) There is a secondary cable that appears to be running to the DW. The positioning of this only makes sense if the LCM-3 is being winched onto the transport.
4) If it was being launched for an operation, it seems unlikely that there would be such a casual atmosphere, with many civilians allowed to watch.