Chapter 63

Aboard the Pretty Penny, the crew watched in horror as the explosion jellied the four men in the water.

Wikipedia says:

The effects of an underwater explosion depend on several things, including distance from the explosion, the energy of the explosion, the depth of the explosion, and the depth of the water.

Underwater explosions are categorized by the depth of the explosion. Shallow underwater explosions are those where a crater formed at the water's surface is large in comparison with the depth of the explosion. Deep underwater explosions are those where the crater is small in comparison with the depth of the explosion, or nonexistent.

The overall effect of an underwater explosion depends on depth, the size and nature of the explosive charge, and the presence, composition and distance of reflecting surfaces such as the seabed, surface, thermoclines, etc. This phenomenon has been extensively used in anti-ship warhead design since an underwater explosion (particularly one underneath a hull) can produce greater damage than an above-surface one of the same explosive size. Initial damage to a target will be caused by the first shockwave; this damage will be amplified by the subsequent physical movement of water and by the repeated secondary shockwaves or bubble pulse. Additionally, charge detonation away from the target can result in damage over a larger hull area.

From the looks of the column of water the scuttling charge was more than sufficient.

A shallow water explosion is classified as one that is less than 500 feet ... these men suffered the effects of a standard WW2 British 'can' depth charge i.e. two hundred pounds of torpex detonated at 75 feet. The explosive used was probably C-4 and only 10 pounds but it was sufficient to fragment the hull of the sub.

It is illegal to fish with explosives but the crews of both cutter and ketch weren't about to let the bounty that surfaced go to waste.

Subsurface explosions draw sharks better than chumming. Fish in the immediate area are fragmented while fish farther out are concussed and many lose their air bladder.

The sub was motoring along a coral reef ... that damage was pretty severe ... underwater explosions affect micro organisms much farther away than they do fish.

The THETIS requested guard assistance from the Pretty Penny. The clear tube was damaged but not badly enough to be destroyed. The THETIS' divers recovered the haul and left to deliver it to the DEA in Key West. Pretty Penny circled the area under sail and watched the site.

Late that night, as one watch was relieving the other, the five mile radar proximity alarm sounded. The radar showed a large vessel approaching, but the watch had seen no lights for quite a while. Since everyone was already awake, David suggested that the sails be lowered and the turbines placed on standby. Andrea maned the Honeywell M142 IHADSS helmet and checked for full integration with the 3mm wave radar.

"I have integration ... I have lock. Activating forward-looking infrared imaging system ... I have multiple images," she said.

From the chart room, Barbara said, "I have multiple water entry. I have underwater breathing."

"Chief, illuminate the target at 500 yards," said Captain Austin.

"Yes, Sir."

"Bofors manned."

"Coast Guard, Key West. Her Majesty's Nevis and St. Kitts Brig of War, Pretty Penny"

"Key West, Pretty Penny."

"We have an unidentified large unlighted vessel approaching. Do you have Cutter in vicinity?"

"No. Take appropriate action commensurate with threat, Pretty Penny."

"We have multiple swimmers in the water."

"Defend yourself."

"500 yards, Captain. Illuminating."

As soon as the searchlight came on the large pleasure craft began firing at the light.

"Light 'em up, crew."

In just seconds, four 40mm proximity fused projectiles removed most of the upper decks and the 30mm alternating high explosive and tracer rounds had stitched a nice series of holes from stem to stern at the waterline ... the fuel tanks exploded and the yacht immediately began to sink. They had been barely able to make their approach through the shallow waters of the reef. The yacht didn't have very far to ground out.

"Divers at one hundred yards. Nothing closer... 75 yards ... Barbara fired up the underwater speaker. "Divers in the water ... retreat, surrender or die ... your choice. She broadcast the message three times. "Fifty yards... 45... 40... 35. Boys?"

Charlie and Chester pulled the pins and threw their grenades.

"Good job, I have thrashing and movement ... it's stopped. Side scan shows three sinkers ... Whoa!! Sharks. Hostile action has ceased."

"Key West, Pretty Penny."

"Key West."

"Hostilities have ceased," David reported. "Chief ... lights on the yacht." Sanchez thoroughly examined the wreckage. "Key West ... no survivors observed. Will remain on station for the next idiot."

"Thank you, Pretty Penny. THETIS will be with you before daylight. Key West Coast Guard, out."

"Her Majesty's Nevis and St. Kitts Brig of War, Pretty Penny, out."

THETIS arrived on station about false dawn.

"Welcome back, THETIS."

"Greetings, Penny. I understand you had all the fun last night. Did you leave us anything?"

"Just the mess, THETIS."

"Oh ... thanks a bunch."

the commanding officer asked, "I have just one question ... were you fired on first?"

"Yes, Sir. Would you care to review the tape?" David said, "I'll record a copy and send over the original."

"The FBI would appreciate that."

"What do they have to do with an offshore engagement?"

"Our sources report a very interested congressman and a couple of local law enforcement departments."

"Well ... we have been trailing several grooves in the bottom ... similar to the groove left by the wire depending from the sub. Our ROV has reached the end of it's tether. Come daylight we will continue tracking. Be advised there are numerous sharks in the area of the yacht."

"Thank you Penny. THETIS, out."

"Penny, out."

The sun came up ... actually, the world turned ... but who cares ... one saying is as good as the other. Penny requested permission to continue tracking the scratches in the bottom ... and follow them they did. Past Key West ... past the old Naval and Marine Air Station ... past several Keys with expensive single dwellings ... past the piers ... and up towards Miami ... but they didn't go very far past the piers.

"Key West ... secure channel please."

Scratches and garbles, static and buzzes.

"Key West."

"Pretty Penny ... you know where the burnout on Long Beach Drive is?"

"We sure do."

"The scratches end there and there seems to be a great many binoculars watching us from the shadows of the burn. The sidescan sonar shows several damaged speedboats just outside the dredged channel and there's a barely submerged pier on the left side of the dredge ... and we are out of here."