Paul steamed silently until Kris tapped his shoulder. 'What's up?'
'Oh, our supportive bull ensign just screwed me again. I suppose he's screwed you plenty of times, too.'
'He'd like to.' She laughed as Paul reacted to the double-meaning. 'Not that he has a hamster's chance in hard vacuum of getting his wish. But as for the sort of screwing you're talking about, don't let it get to you. Life's too short. Days are too short.'
'How do you keep going, Kris? Every time I see you, you're in motion.'
'My mind's always five minutes behind the rest of me. By the time I realize I'm exhausted, I'm already past that point and doing something else.'
Carl Meadows stopped at an access hatch leading toward the outer hull, keying the monitor next to it. 'Lieutenant Meadows, Ensign Denaldo and Ensign Sinclair accessing maintenance trunk B-205-E.'
An engineering watch stander responded, his voice tinged with boredom at the routine. 'Purpose of access, sir?'
'Officer qualification review.'
'Anticipated duration?'
'Fifteen minutes.'
'Permission granted to access maintenance trunk B-205-E, Lieutenant Meadows. Notify the Damage Control watch upon exiting the space.'
'Affirmative.' Carl cracked the hatch, its squarish dimensions betraying the constricted nature of the maintenance trunk it guarded, then waved Kris Denaldo through. 'Ladies first. Paul, you follow me.' Paul fought down a tinge of claustrophobia as he watched the other two swing inside a tunnel-like access trunk with sides measuring only about a meter wide. As if sensing Paul's misgivings, or perhaps remembering his own experiences, Carl grinned back at Paul as he swung in. 'We're lucky, you know. If they didn't have to make these things wide enough for someone in a full protective suit to squeeze through they'd be a lot narrower.'
'Lucky us.' Paul followed cautiously as the small party moved several meters along the trunk before Carl called a halt.
'Okay.' Carl Meadows pointed to the outer surface of the trunk they were in. A pattern was visible there, of hexagons joined at every side and repeating as far as could be seen. 'Ensign Denaldo, what are we looking at?'
'The water-blanket.'
'That's its nickname. The official nomenclature is…?'
'Sorry. That's the Ship's Inner Hull Thermal Absorption Barrier System. Mark Four.'
'Mod?'
Denaldo twisted to look back at Carl, her expression exasperated. 'Why do I need to know the mod? This is a, uh, Mod Two. But that doesn't matter, because the only difference between the different models is superficial.'
'Who told you that?'
'Jen.'
Carl nodded. 'Jen's right, but you're wrong. Why do have to know the mod number? Because your qualification standards say you have to know the mod number. And that means when you go up for a screening board they'll ask you the mod number.'
'So I have to know it not because it's important but because I'm going to be asked anyway?'
'Exactly. Sometimes it is important to know the mod number, so they make you know it all the time. Okay, here we have a Mark Four Mod Two Ship's Inner Hull Thermal Absorption Barrier System. What's it do?'
'What it says.' Kris waved her hand at the hexagonal honeycomb. 'Every one of those hexagons outlines a cell filled with water and interconnected to every hexagon next to it. That water barrier forms the inner hull of the ship, and absorbs all the heat generated by the crew and equipment.'
'What else does it absorb? Paul?'
Paul swallowed, thinking through his answer before replying. 'It also absorbs any incoming heat or radiation striking the outer hull. That protects the crew from radiation, and our reflected heat signature is reduced to a minimum, making the ship harder for anyone to spot against the background of space.'
'Right. Why do we use water for that?'
'Because water is the best heat sink in the known universe?'
Carl nodded. 'Right again. It also stops radiation pretty darn good, and using it as a barrier gives us a place to store water we need for the ship and crew anyway. But what happens to the heat this stuff absorbs? Kris?'
'It gets circulated by pumps, with higher temperature water cycled toward the main machinery room. Once it gets hot enough there, they run it through a low pressure tube-'
'Which is actually named?'
'A Venturi tube. Increases velocity and reduces pressure. The hot water flashes to steam, and the steam gets shunted to counter-rotating turbines which supply some of our electrical power. We convert our own waste heat into another source of energy we can use.'
'And recycling everything out here is a real good idea. Unfortunately, as Ensign Shen will tell you, those turbines like to break down just when you need them the most, and if one goes down you have to take down its partner as well. Paul, why do we need counter-rotating turbines?'
'Because if we just had a turbine going in one direction its torque would force the ship to rotate.'
'Uh-huh. And what happens if something knocks a hole in the inner hull? How many water cells do we lose?'
Paul hesitated, then spotted Kris Denaldo waving her hand at him, one index finger extended. Oh, yeah. I know this. Thanks, Kris. 'One. Seals activate automatically on all six sides to isolate a cell if there's a pressure drop.'
'And why is having a shield of water armor real useful in combat?'
'Because the water flashes to vapor when it gets hit. That dissipates the energy of the hit on the ship as well as anything could.'
'Excellent. What a fine crop of ensigns we have these days.' Carl, pretending to ignore the rude responses of Paul and Kris to his sarcasm, hauled out his personal data link and tapped in some information. 'Congratulations. You two have just signed off some of your damage control and engineering OSWO qualifications.'
'Thanks, Carl.' Kris gestured down the way they'd come. 'Can we egress the exit now? I've got things to see and people to do.' Moments later, they were out of the access trunk, Paul luxuriating in the suddenly expansive- seeming confines of the corridor, and Kris Denaldo was swinging rapidly away. 'See you guys around,' she called, before vanishing around a corner.
Paul shook his head. 'Does she ever slow down?'
'Not that I've ever seen.' Carl sighed audibly. 'That babe is too damn driven. No off switch and her main drive is battle-shorted on full speed ahead. She's going to run into a brick wall someday and fly into lots of little pieces.'
'Can't anybody get her to slack off before then?'
'They've tried. I've tried. The only one who might be able to work it is the XO. She could stop a good-sized moon in its tracks just by glaring, I think, but so far she's letting Kris run. I guess Herdez wants her to set her own limits instead of having them imposed.'
'I hadn't thought of that.' Paul suddenly found himself yawning hugely. 'Sorry. I had the mid-watch. I think I got about four hours sleep last night.'
'Well, there's your problem, Ensign. You aren't getting enough done because you're spending too much time in your bunk.' Carl grinned, then sobered. 'Seriously, though. I know there seems to be four times too much to do every day, because there is four times too much to do every day, but if you'd take a bit of advice from an elderly lieutenant junior grade you'd set aside enough time each week to get two or three OSWO qualification standards signed off. It may seem to be adding another complication, but by keeping your Department Head happy it's actually simplifying your life no end.'
'Thanks, Carl. I appreciate the advice.' Paul's own data link chose that moment to chime urgently. He checked the display, reading carefully since he didn't trust himself to scan text after so little sleep. 'MA1 Sharpe is
