So I am guessing, this was the reason my ship had catwalk watches while in DaNang Harbor. A 4 hour watch, walking back and forth on the catwalk, armed with an old M1 Garrand ... looking for trash in the water, or anything that could effectively hide, a swimmer, trying to get close to a ship to plant charges. In the various visits to the harbor ... there may have been two suspicious masses of floating garbage seen. One I saw ... was large enough to disguise a swimmer, was moving in an odd manner ... so I contacted the OOD, who came down, with a concussion grenade. He confirmed it looked suspicious, Handed the grenade to me, and I threw it into the collection of floating rubbish.
It exploded, no evidence of a body or swimmer, so after twenty minutes, the OOD returned to his coffee, and I continued my watch for about an hour more, until I got relieved and went to my rack.
The only other excitement for being on a catwalk watch was when the VietCong, shelled an airstrip and happened to catch a fuel depot. As always it seemed the skies were heavily overcast, with thick clouds, that turned bright orange with the flames of the fire after the explosion. We were too far out, to see the flames, or even hear the explosions, but the entire sky turned orange, due to the fire off the clouds.