When Certainty Drifts | Ken Woodward #101

Once a submarine goes under, nobody aboard knows precisely where they are.

Those who haven't lived the experience are surprised when I say that.

They picture a glowing screen with a dot on it that says, "You are here." Imagine somewhere as a cross between a shopping mall map and one too many science fiction movies.

Underwater, there is no dot.

There's an estimate.

The navigation team knows the speed.

They know the heading.

They know how long the boat has been running.

From those three things, they plot where the boat ought to be.

That's dead reckoning, and dead reckoning drifts.

A current leans on the hull, and an instrument carries an error so small nobody would notice it in an hour, but the hours add up.

The, the plot looks clean.

The boat feels steady.

Nothing in the moment says anything is wrong, and that's the unsettling part.

Being off course feels exactly like being, well, on course.

So every so often, the boat comes up to periscope depth, just high enough to get an antenna out of the water and take a GPS satellite fix.

The fix says where the boat actually is.

The team compares it to where they thought they were, corrects the plot, and the boat goes back down deep.

Coming up isn't free.

A submarine's best protection is being hard to find, and near the surface, some of that gets traded away.

To get the truth, the boat accepts a little exposure.

I was a radioman.

The radiomen and the quartermasters, the navigators, answered to the same boss in our division.

Going in and out of port, I stood with the navigation party, plotting coordinates as the navigation points came in.

Piloting into a harbor, one bearing doesn't give you a position.