Sam and Tom quickly went through the rigorous process of setting up and testing their equipment. Sam opened the aluminum backpack. Inside was an axial type scrubber unit filled with the granular absorbent used to remove C02 from the closed-circuit during the dive. He removed the half-used cartridge and replaced it with a brand-new unit, filled with five pounds of sodalime and then reinserted it, locking the lid with a heavy-duty thread.
He worked his way through, testing two times for leaks. These are the positive and negative pressure tests, and are designed to check that the breathing loop was airtight for internal pressure lower and higher than the outside. The positive pressure test ensures that the unit will not lose gas while in use, and the negative pressure test ensures that water will not leak into the breathing loop where it can degrade the scrubber medium or the oxygen sensors.
Sam and Tom methodically and efficiently worked their way through their dive equipment, going through the laborious process of preparing each part for the dive.
Confident that their systems were in working order and that their multiple redundancy systems worked too, they finally donned their thick dry suits.
Sam pulled the hood of his neoprene dry suit over his head. “Are you good to dive, Tom?”
Tom had already slipped his arms through the aluminum backpack of his closed-circuit rebreathing system, that was designed to mold to his back. “I’m good whenever you’re ready.”
“All right.”
Gene stepped down to the platform with one of the engineers. “How long are you going to be?”
“Shouldn’t be long,” Sam replied. “Under an hour.”
“And what do I do if you take any longer than that?”
Sam shrugged. “Any of your engineers capable of diving in confined spaces?”
“No. We have two commercial divers on board who can do some steel welding if required, but they’re working with atmospheric dive suits, so there’s nothing they can do for you if you get stuck.”
“All right. I guess you’re back to waiting.”
“For what?” Gene persisted.
“Until we get ourselves out of whatever trouble we found.”
With that final thought, Sam donned his full-face dive mask.
He took a deep breath and started pre-breathing the unit — a process of breathing normally for about three minutes before entering the water to ensure the scrubber material gets a chance to warm up to operating temperature, and works correctly, and that the partial pressure of oxygen within the closed-circuit rebreather is controlled within the predefined parameters.
Sam inhaled effortlessly.
The gas he breathed was humid and warm, rather than the dry, cold air divers are used to with compressed air and a scuba cylinder and regulator set up. In the frigid waters of the Northern Sea, that would be a welcome bonus.
He checked his gauge for two things.
One, that C02 levels weren’t rising, meaning the new sodalime scrubber was doing its job correctly and two, that the partial pressure of oxygen within the closed-circuit remained within the initial setpoint of 1.3 bar.
Sam ran his eyes across the top reading, where a nondispersive infrared sensor showed that the C02 levels weren’t elevating.
Below that, his glance stopped to examine the reading from the oxygen analyzer. It showed the partial pressure of oxygen as 1.3 bar.
Three minutes later, he radioed Tom, “I’m all good to go.”
“Sounds good,” Tom replied. “Let’s go see what went so disastrously wrong.”
Sam slipped his dive fins on, switched on his flashlight and slid into the narrow space of the Buckholtz’s flooded internal stairwell. The water was cloudy with mud, but the visibility was good enough to clearly make out the shapes of the steps and walls which made up the flooded stairwell. The beam of his flashlight was able to reach the engine room three decks below.
He deflated his buoyancy wing until he was negatively buoyant and started his descent in a counter-clockwise direction, following the stairs to a depth of thirty feet and stopped. There, he checked his gauges, confirming on his heads-up display that his CO2 levels weren’t climbing and that the partial pressure of oxygen within the fully closed-circuit remained within the predefined parameters.
Sam glanced at his buddy. “How are you doing Tom?”
“Good,” came Tom’s cheerful reply. “All gauges in order.”
“All right, let’s continue down into the engine room.”
Sam swallowed, equalizing the pressure in his ears and sinuses and occasionally inserted a small amount of gas into his dry suit to prevent its compressed air from squeezing him tight. At a depth of sixty feet, the stairwell opened onto a level steel gangway.
The engine room sprawled across four full decks, making it the largest open space on board the entire ship. He flicked his flashlight around the engine room, its beam striking a series of large turbines and the massive prime mover engine, used for the Buckholtz’s primary propulsion, before finally settling on a closed hatch at the very bottom.
Sam said, “That’s it.”
Tom fixed his beam on it. “That hatch there?”
He descended quickly, as the flooded compartment allowed him to skip what would have otherwise been a ladder spanning four decks.
Sam played with the steel lever until the hatch came free, and he opened it fully. “That’s our opening to the duct keel.”
Tom said, “Why’s it shut?”
“What do you mean why’s it shut?” Sam asked. “It’s meant to be shut. It’s designed to be water-tight. Otherwise, what’s the point of having it.”
Tom tilted his head to the side, as though Sam had already answered the question. “That’s exactly why I’m wondering why its closed.”
Sam swallowed. “You’re right. If it was water-tight, and the damage was done inside the duct keel, none of the water should have reached the rest of the engine room. And if the flooding occurred elsewhere, there shouldn’t have been any water inside the duct keel.”
“Exactly. Any ideas?”
“None. Unless there are two damaged sections of the hull?”
Tom shined his light into the dark tunnel. “Let’s hope there are some answers down there.”
Sam pulled himself through the manhole.
It was small enough that he had to consciously position himself so that his arms and larger closed-circuit rebreather system could squeeze through, the same way he might during a cave dive. The entrance led to two sets of vertical ladders, which descended another twenty feet.
He made the descent, carefully diving head first because the ladders didn’t allow for anything else. At the bottom, there was a second manhole. Sam quickly maneuvered the hatch and swam through.
The duct keel was an internal passage of watertight construction, comprised of two longitudinal girders spaced precisely eight feet apart to form a narrow tunnel running just shy of the entire 1400-feet length of the Buckholtz.
Two sets of large piping took up most of the space. One pipe to shift the storage of the heavy fuel oil used to drive the large shipping vessel, and the second one, to maneuver the ballast water to maintain an even sail and to compensate for swell.
Tom’s flashlight flickered past Sam’s shoulder, disappearing far into the distance.
Tom said, “Any idea how we’re going to get across the length of this thing?”
He fixed his flashlight on a pair of horizontal carts that looked awfully similar to old mine carts, with a single set of narrow railway tracks that disappeared into the blackness of the tunnel. At the back of the cart was a simple mechanical arm — known as a walking beam — that pivots, seesaw-like at the base, which the passengers alternatively push down or pull up to move the cart.