Captain Stewart studied the scene through his binoculars. The Edisto had just swung parallel to the coast and several hundred yards out, unwilling to follow the cabin cruiser onto the beach. A small storm of white geysers suddenly erupted from the water around the cabin cruiser, which was now visibly heeled over to port close to the rocky beach. Several seconds later he heard the insistent rattle of chain-gun fire; Edisto was firing a long burst from her 25mm Bushmaster cannon.
Seconds later another player entered the scene — a police helicopter, swooping in low above the shoreline, then coming to an ominous hover. Smoke was rising from the cabin cruiser now.
"Bridge, this is the diving officer," a voice called over the intercom. "Depth-below-keel is twenty fathoms."
"Very well. Prepare to dive."
"Prepare to dive, aye aye."
Stewart looked around. "Clear the bridge!"
The two lookouts ducked down their holes, the pressure doors slamming tight above them. "Our last look at daylight for a while, Skipper," Shea said. "After you, sir?"
Stewart took a last look at the shore, then nodded and climbed down into the sail well. Above him, Shea secured the cockpit, pulling in the Plexiglas windshield and securing it, then dogging tight the pressure hatch.
Stewart scrambled down the long ladder and emerged in the control room, just abaft the periscopes. Lieutenant Myers, who was Officer of the Deck this watch, looked up from the chart table. "Captain on deck!"
"As you were," he said. "Diving Officer! Take us down, periscope depth."
"Take us down, periscope depth, aye aye, sir!"
The water was shallow yet. At periscope depth they'd damned near be scraping barnacles — if there'd been any barnacles to scrape on Ohio's newly scraped, cleaned, and painted keel. But Stewart wanted to get her down into her real element… the silent darkness below the surface. That pleasure boat up there might have been the only attacker, but it was also possible the attacker had been the first of several, possibly set up in layers. That way, just when the Ohio's crew thought they were in the clear, just when her escort had been pulled out of position, another ambush would be sprung. A Stinger missile might not have made much of an impression on Ohio's tough skin, but what if there was someone up there with a military surplus Exocet?
Good sub drivers didn't take that kind of chance.
"Flood main ballast," the D.O. ordered. "Five degrees down plane."
The deck tilted beneath Stewart's feet, and the Ohio slid gently into the depths.
8
This is nuts, Hawking told himself. Submarines don't want to be found!
During his tenure as a naval aviator, he'd joked often enough about "postage stamp landings"… about what it was like dropping out of rain clouds or darkness in an F/A-18 to trap on a carrier deck, and about how tiny that deck looked from the air. A super carrier was a floating colossus, over a thousand feet long and displacing in the neighborhood of eighty thousand tons, but it looked like a freaking postage stamp from the air, and a moving postage stamp at that.
But the aviator had access to a whole array of navigational data — radio beacons and radar and GPS fixes beamed to him by satellite. He might not be able to see the carrier until the last moment before he came in over the fantail, but he knew exactly where it was.
Not so with submarines. Even something as large as an Ohio SSGN was a tiny, tiny sliver in a very large and opaque emptiness. No radio beacons. No satellite signals unless you had an antenna extended above the surface. Blue-green lasers penetrated seawater to a degree, allowing communications over limited distances, but you pretty much had to be on top of the other guy before that became practical.
As always, as it had been for decades, sound was the best way to spot a target. The trouble was, submarines went out of their way to eliminate sound so the enemy couldn't track them. Both Ohio and the Manta had sonar, of course, and by going active, either vessel could pinpoint the other in a matter of seconds.
This was an exercise, however, intended to simulate possible submerged operations in potentially hostile waters. Ohio wasn't broadcasting. She was listening.
And so Hawking was doing the broadcasting, and he was doing it on a very narrow frequency, at very low power. It was, he'd been told, the same sort of low-power sonar pulse used by Ohio's diving officer to determine the depth beneath the keel, a signal so weak that other submarines wouldn't pick it up unless they were quite close — within a few thousand yards, say.
To Hawking, who was used to a distant horizon in a fighter — CAVU, or Ceiling Absolute, Visibility Unlimited — this felt like a blind man feeling his way through a dark cellar at night, using a stick to try to identify that one postage stamp that had to be in here somewhere….
At eighty-five meters the water was as dark as it had been at ten times that depth, without even a trace of illumination from the surface. The one difference was that this far from the bottom there was less particulate matter, no drifting flecks of muck imitating stars.
And no fish, either. Hawking had wondered about that during his various training dives and test runs with the Manta. Only rarely had he actually seen signs of sea life, and then only in the upper few tens of meters of sea. The ocean — out here away from the shoreline, at any rate — appeared to be a barren and empty desert.
A warning light flickered on his control screen, accompanied by a tone over his headset. Contact! Weak as his sonar emanations were, they'd reflected off something large somewhere up ahead. He banked the Manta to the right, bringing his heading onto a direct line with the contact, and increased his speed.
If it was the Ohio, they would hear him coming, of course. Unlike conventional submarines, the Manta was not specifically designed as a quiet submersible. It wasn't that noisy, either, but at speeds of more than about twenty knots, he'd been told the Manta sounded like one of those bicycle noisemakers he'd employed as a kid, a piece of cardboard attached to the wheel in such a way that it made a motorcyclelike clacking as it turned. This was due to the Manta's aquafoil design, which, like an aircraft wing, was shaped to create greater pressure below the vessel than above it, providing lift. When the two unequal streams of water met and mixed aft of his wing, they created turbulence, and that announced his presence as clearly as if he'd come in with horns blaring. The water jet used for propulsion was noisy as well. There were no moving parts, but the rush of water through the aft venturi created a kind of freight-train rumble in the headphones of submarine sonar techs in the area.
So at the moment, not only was the Ohio pinpointing his position by sonar, but every other submarine and undersea sound sensor from here to Midway Island must be picking him up as well. The trick was for him to pick up the echoes from the very quiet submarine somewhere up ahead.