USS San Diego makes grand entrance into San Francisco for Fleet Week

SAN FRANCISCO (KGO) -- If you looked toward San Francisco Bay on Monday, you may have noticed a large ship steaming in through the gate. You may have also noticed the ship's crews lining the rails. There is a method and tradition to this.

TIMELAPSE VIDEO: USS San Diego journeys across San Francisco Bay for Fleet Week

It was a most serious face, one of hundreds on the USS San Diego on Monday.

One person said, "I would not say it is a drill. It is a tradition."

They call it "manning the rails." And during this Fleet Week, you'll be seeing quite a lot of it.

One member of the military said, "Seeing all of the young men and women in uniform, it is a beautiful thing."

It's reassuring, too. The tradition evolved from a time before radios, when sailors on a warship would man the rails in a foreign port as proof that they had no hostile intent.

Nowadays, it has evolved into an act of respect for a port. Shipmates stand immobile; no talking, either, even in a rainstorm like the one on Monday morning.

We were told, "You do it rain or shine. Doesn't matter."

Being able to witness such a moment took considerable doing. First there was a helicopter ride on a Navy chopper from San Francisco International Airport that went under the Golden Gate Bridge, then out to sea, and onto the ship as it sailed towards the city. Then, we met the brass.

"Presence - we are demonstrating what the Navy does to provide presence and force as necessary on a daily basis," said USS San Diego Executive Officer Captain Pete Collins.

This was a day when the Navy hosted fire, police, and other emergency response agencies in a show and tell.

In war this ship deploys Marines and equipment. But after a natural disaster like a major earthquake, it can also send those same men and machines to help a stricken city.

"I think this would be like a resource where you'd bring everyone together, a command post," said SFFD Lt. Rob Neuneker.

All of which, no doubt, left a strong impression.

But even that could not match the nobility and dignity of a ship's crew arriving in port, manning the rails.

As we said, get used to it this week.

Click here for a full list of Fleet Week events.