The Post incorrectly identified the helmsman aboard the Navy training boat Mistral in a story in Sunday's editions. The helmsman was Gen. Robert Taber.

"What's that rule?" Gen. Robert Taber asked as we cruised the gentle swells of the Atlantic off Montauk Point, Long Island.

"Murphy's Law, right?" he answered himself. "If something can go wrong, it will go wrong."

He had just constructed a little exercise for the 12 Naval Academy midshipmen he is leading on a two month sailing cruise from Annapolis to Nova Scotia to the Virgin Islands.

The exercise: to plot the course of an approaching ship on the radar rig aboard the Mids' 65-foot training schooner Mistral. This was no collision course, but things had been quiet and, as Taber put it, "You've got to take your excitement where you can on a cruise like this."

He got a little more than he bargained for.The blips weren't on the screen two minutes before the whole enterprise went blooey.

The ship, passed harmlessly off the starboard side, and Taber was stuck with the prospect of plowing into New England's fog-plagued waters with his radar on the fritz. Given Murphy's Law, pea soup was inevitable.

The fog in these waters doesn't creep in on any little cat feet. It comes bounding over the gray-green water like a tiger on the prowl, socking you in from stem to stern before you can remember what your bowsprit looks like.

"Gee, look at that," said Mid Jeff Asher as we passed Buzzards Bay tower a few hours later. It was our third day out of Annapolis under nothing but bright skies and gentle, fair winds.

Asher was pointing at the huge structure, which looks from a distance like a deep-sea oil derrick. It was a half-mile away and already losing its outlines in the evening mist.

Two minutes later Asher looked over the stern again and saw nothing but gray banks of sea-level clouds gaining on us, 50 yards off the stern.

Then we were blind, enveloped in the soup."All right," said Taber, warming to the challenge, "this is critical. I want you to hold course very tightly. We have nothing to go on but navigation and this is a shipping lane. There will be big ships.

He barked orders to the chart room.

"What's our next mark and when should we reach it?"

There was a clatter of pencils, dividers and papers shuffling below. Ensign Al Nugent, freshly graduated from the Academy, poked his head out.

"Hold course for now. We should have a bell buoy off the starboard bow in about 20 minutes."

It was an agonizing 20 minutes, complicated by Mistral's winding route through strings of lobster pot markers.

The hands on the chronometer ticked off 15 minutes, then 20. Still no marker. The tension was getting as thick as the fog. To escape the pressure some of the crew took off below decks for supper.

Two bites into a cheeseburger and there came a tremendous thump from above.

We jumped to, expecting when we hit the deck to see the nose of some tugboat perched over Mistral's rail.

Instead we found the boom clattering and banging from a sudden squall and Taber at the helm, his eyes alive.The Mids leaped to his orders to gather in the mainsail; the winds whistled through the rigging; off the starboard beam, 15 feet from the boat, the bell buoy tossed and clanged in the choppy sea, shrouded in mist.

The mainsail came down with a crash, the big diesel engine roared to life and course was altered to safe harbor in New Bedford, where the radar would be repaired. Ten minutes later fog banks lifted and smiles crossed the crew's faces.

Question: does it make sense in this age of the nuclear navy to be sending a dozen officers-to-be off on a two month romp around the islands of the Atlantic in a 40-year-old sailboat/ Answer: until Murphy's Law gives out, why not?

There's a lot of controversy about this program," said Taber, a retired three-star Army General. "A lot of Navy higher-ups think these kids ought to be studying computers."

Then there are others, like the brass at Annapolis, who approved Mistral's tour, who think it doesn't hurt a bit to have Navy officers who can find a bell buoy in a foggy squall off the tempestuous New England coast with nothing but a compass and a sextant.

Or pick out stars, planets and constellations on a cloudless night while the wind rattles sheets and halyards, or pull dolphin from the Gulf Stream with nothing but a handful of line, a hook and a shining silver spoon.