The most mournful sound aboard came from the ship's "whistle". We did not use it often. But sometimes the repetitious, plaintive sound of the whistle dominated the rhythms of life and of introspection aboard the boat.

The actual horn that we called a whistle was located on the forward edge of the sail, perhaps a foot above the deck. The handle for operating it was on the bridge, convenient for the use of the Officer of the Deck. The whistle was an air horn, far louder than any trucker's monster horn. The sound of our whistle was much like that of the foghorns around the edge and mouth of today's harbors.

We used the whistle just as any surface ship did, signalling our intentions (Inland Rules) or our actions (International Rules). Short blasts, long blasts, prolonged blasts (depending whether Inland or International) all had meanings, when cleverly grouped together as specified in the Rules of the Road. Proper use of whistle signals is an important topic in cases at Admiralty Court.

(The U.S. is the only nation in the world with its own unique set of rules for piloting and navigation on inland waters. Fortunately, International Rules are the same in Copenhagen and Lisbon, Montego Bay and Shanghai, Murmansk and Capetown.

(And the U.S. even has two distinct sets of rules, the Inland Rules and the Western Rivers Rules. And the Western Rivers rules apply as far east as Alabama.)

On consecutive years I was the duty officer on New Year's Eve, and I was asked each year for permission to blow the ship's whistle at midnight to acknowledge the arrival of the new year. Each year I assented. Then I returned to the ritual of writing the smooth deck log in meter and rhyme, as is traditionally done for the watch during which the year changes.

But the soul-stirring use of the ship's whistle happened when we were in the fog. We slowed to seven knots, a speed chosen solely based on decisions in the Admiralty Courts over the years. The speed limit in fog is not specified in the Rules of the Road. We could achieve seven knots easily with one engine, so the other Diesels were all shut down, making the evening quieter for many of the crew. And we sounded the ship's whistle.

The rule calls for a short blast every minute. Good practice calls for staggering the intervals slightly, in case another boat nearby is signalling in unison with your own whistle. The process was tedious, reflexive, hypnotizing.

Fog at sea is almost always accompanied by still air and still water. The entrance to San Francisco Bay is unique with its moving fog. In any other fog, the gentle slapping of the waves against the outer hull is much quieter than usual, almost as if we were in port. The lone engine is lightly loaded, therefore quieter than usual. There is no wind noise. An occasional sea bird squawks, inviting the question of how they navigate at such times.

Then, at night, our navigation lights glow against the fog. There is a question of whether the lookouts should use binoculars or not. The loudspeaker on the bridge, over which the general announcements below are overheard by the isolated occupants of the bridge, seems obscenely loud at a time like this. The lookouts don't need to yell to be heard. In fact, they can almost whisper to the Officer of the Deck about the lack of visibility.

But the whistle dominates the process.

The whistle is painfully loud to the watchstanders on the bridge. The contrast of the whistle's loudness with the otherwise mesmerizing quiet is almost paralyzing.

The whistle is loud enough to interfere with conversations below, in the control room and in the wardroom. The rhythm of the whistle becomes the rhythm of the ship, even of the people who are sleeping. As the crew watches the movie, the whistle sometimes interferes with proper understanding of the dialogue. At first, the whistle interferes with the ability to fall asleep. Then, the whistle becomes a part of sleep, a part of life's rhythm.

Once, as we were approaching and transiting the Irish Sea, we were in the fog for three days. The whistle sounded incessantly. We used a lot of compressed air to feed the whistle. We got so far behind at that speed that we rescheduled our rendezvous with the surface forces, and we established our arrival time in Cherbourg, based on an assumption that we would be in the fog all the way.

Then one morning at about 2:30, (0230 hours, five bells of the midwatch, even though we never rang the bells on the submarine except for some extremely rare ceremonial occasions), with no warning, the fog lifted. Or rather, we chugged our way out of the edge of the fog. There were stars. The world was different.

I picked up the the sound-powered telephone, and I told the quartermaster of the watch to enter in his notebook the time at which the fog lifted. And I stopped blowing the whistle. One of the lookouts, a Seaman Apprentice who had just recently been promoted from mess cook to lookout, commented that he was looking forward to sleeping without that damned whistle going off every minute.

The first call came perhaps three minutes later. The executive officer wanted to know what was wrong. I told him that we were out of the fog, so I was no longer whistling our presence. Seconds later the skipper called, demanding to know what the problem was, and why was I discussing it with the exec instead of the skipper, who was supposed to be the first to know everything. I reminded him that it was not yet time for his wake-up call, and that neither his standing night orders nor the specific orders for that night required me to wake him to announce the absence of fog.

A few minutes later I got the third call over the sound- powered telephone, this one from the chief of the watch. Our hospital corpsman happened to be the chief on that particular watch. He was bemused that he was calling me for this particular reason. One of his responsibilities was to notify me of any unusual occurrences below decks during my watch.

Everybody aboard was awake, up and about. They could no longer sleep without the fog whistle.