Early in my Western Pacific deployment (WESTPAC) on USS Truxtun, the old-timers who had made a WESTPAC a year and a half earlier often told us new guys about what we were in for. The South China Sea, they said, is a horror of wind and stinging chilly rain and waves as big as mountains. The Indian Ocean, on the other hand, is as still as a pond, and you can see the wakes of sea snakes and flying fish for miles.
Reality for me turned out to be quite different. That June of 1978, the South China Sea was as still as a pond. Though there were no sea snakes that I saw, you could see the wakes of flying fish (seemingly) for miles.
The Indian Ocean that July and August was a horror of unceasing wind and stinging chilly rain and waves as big as mountains. It was too rough to be above decks most of the time, and even when the wind and waves abated to the point of being merely rough, it was unpleasantly chilly, even on the equator. Most of the time, you couldn't tell where the wind-driven salt spray ended and the wind-driven horizontal rain began.
Below decks, on the other hand, was like a sauna. Ships cool their interior spaces by making chilled water from the seawater, and the seawater was 82 degrees! It was a cool day when the engine room was below 100 degrees, and the relative humidity was always in the nineties.
Where I most often stood watch was in the Auxiliary Reactor Controls station. This was one of the coolest places in the engine room. Machinists Mates often left a stack of sodas in my workspace to keep them cool while they stood their watches out in the main spaces of the engine room. But right outside the starboard door to my workspace was the deaerating feed tank (DFT). The vicinity of the DFT was one of the hottest places of the engine room. When I had to leave the comfortable confines of Aux Controls to make my rounds, I'd hold my breath as I hurried past the DFT.
Conditions were not much better in the topside interior spaces, though the 85-degree mess decks were a relief after a four-hour purgatory in the engine room.
Theoretically, you might be comfortable standing halfway through a door to the weatherdecks. But, of course, you can't block traffic, nor keep the doors open.
Once we got to higher latitudes in the austral winter, it got to be comfortably cool in the engine room. The chill topside was now due to temperature, not to wind and rain. While the sea was still rough, there was not so much rain and spray as there had been in the tropics. And now, people on watch began hanging out around the DFT, warming their hands above it as if it were an old-fashioned wood-stove on a chilly day.
The difference between my WESTPAC and the previous was the time of year, and most especially the monsoon. I was there when the monsoon was just beginning in the Indian Ocean and had not yet tracked eastward to the South China Sea. On the previous WESTPAC, my senior shipmates had encountered the monsoon in the South China Sea later in the year, and went to the Indian Ocean after the monsoon had left.
One month in the annual monsoon cycle makes the difference between "still as a pond" and "waves as big as mountains."