Lifeboats

[Anthony]

Originally posted by flykiller:
for some perspective, perhaps we can evaluate some actual examples. consider two ships, both 4000 tons, HG2. The tech 10 passenger liner has 312 staterooms, and carries 10 lifeboats for a total of 260 tons or 6.5% of total ship volume. the tech 15 scout cruiser has 95 staterooms, and carries 3 lifeboats for a total of 78 tons or 2.0% of total ship volume. the monetary cost of the lifeboats is of course inconsequential in light of the cost of the ships.

Probably not true. Cost per dton is probably comparable to or greater than the cost of the main ship, so figure 6% in the first place, 2% in the second. How many people actually fit in a 20 dton lifeboat anyway?

1) can the lifeboat tonnage cost be described as a "vast penalty"?

Well, without those lifeboats, the passenger ship would have 20% more staterooms; in addition, the ship costs more. I consider somewhere around a 25% increase in costs a 'vast penalty'.

2) if the lifeboats are discarded, can the recovered tonnage be used to make the ship itself more reliable? if so, how much more?

Depends on what you think the points of failure are. On a high guard design, that's enough to put in a complete backup power planet and either M-1 or J-1 drive, which will certainly make the ship more robust.

 

[flykiller]

</font><blockquote>quote:</font><hr /> for some perspective, perhaps we can evaluate some actual examples. consider two ships, both 4000 tons, HG2. The tech 10 passenger liner has 312 staterooms, and carries 10 lifeboats for a total of 260 tons or 6.5% of total ship volume. the tech 15 scout cruiser has 95 staterooms, and carries 3 lifeboats for a total of 78 tons or 2.0% of total ship volume. the monetary cost of the lifeboats is of course inconsequential in light of the cost of the ships.

Probably not true. Cost per dton is probably comparable to or greater than the cost of the main ship, so figure 6% in the first place, 2% in the second. How many people actually fit in a 20 dton lifeboat anyway?</font>[/QUOTE]3.1% in the first case, 1.1% in the second. not probably.

as for capacity, it depends on your ruleset. earlier in this thread I posted a link to my deckplan for a lifeboat. take it as you will.

 

[kaladorn]

Some interesting real life lifeboat development

This gives an idea of how lifeboats should be laid out and what overcapacities are involved along with how lifeboat vs. liferaft design and exit strategies from the boat have evolved.

I'm not so sure I'd be keen to wait for a 'rescue boat' ....

 

[flykiller]

</font><blockquote>quote:</font><hr />1) can the lifeboat tonnage cost be described as a "vast penalty"?

Well, without those lifeboats, the passenger ship would have 20% more staterooms; in addition, the ship costs more. I consider somewhere around a 25% increase in costs a 'vast penalty'.</font>[/QUOTE]good point, but this is a change of subject. your original position was that lifeboat space was better spent on making a ship more robust in the first place. you now appear to be disregarding the issue of crew/passenger safety/recovery altogether, advocating both no lifeboats and no backups.

may I ask you also to consider the scout cruiser? surely you would not make the same argument with it?

</font><blockquote>quote:</font><hr />2) if the lifeboats are discarded, can the recovered tonnage be used to make the ship itself more reliable? if so, how much more?

Depends on what you think the points of failure are. On a high guard design, that's enough to put in a complete backup power planet and either M-1 or J-1 drive, which will certainly make the ship more robust.</font>[/QUOTE]on the HG2 tech 10 passenger liner, eliminating the lifeboats would indeed make room for a backup power plant 1 and a backup maneuver drive 1, and that would indeed make the ship more robust against some kinds of casualties. it must be pointed out, however, that such backups are seven times more expensive than the lifeboats. does this increased cost count as a "vast penalty"? it must also be pointed out that while the backup drives will help in some casualty situations, perhaps even many, yet the lifeboats will be of use in almost all such situations. since we don't know what the points of failure (ahem) might be, the lifeboats seem more responsive.

and, again, may I ask you also to consider the scout cruiser? what added robustness would you propose in place of its lifeboats?

 

[Anthony]

Originally posted by flykiller:
may I ask you also to consider the scout cruiser? surely you would not make the same argument with it?

No, I'd argue that the scout cruiser is so unlikely to get in trouble anywhere where lifeboats would do any good that it's not even worth worrying about.

it must also be pointed out that while the backup drives will help in some casualty situations, perhaps even many, yet the lifeboats will be of use in almost all such situations.

Almost every time, the best option is 'fix the ship'. The basic issue is:

If you get in trouble in the middle of nowhere, you need to be able to get back to somewhere. That means you need a jump drive.

If you get in trouble somewhere significant, there's probably going to be rescue craft available long before you're in significant trouble.

and, again, may I ask you also to consider the scout cruiser? what added robustness would you propose in place of its lifeboats?

A machine shop and supplies of parts.

 

[Drakon]

Originally posted by kaladorn:
Power plant problem: fusion power plants don't have meltdowns. If you have enough time to get into lifeboats, you have enough time to turn the power plant off.

Originally posted by Anthony:
Maybe. Assuming everything works. They could have coolant system failures. They could have failures damping the reaction out. They could have other failures which actually exacerbate the problem.

Of course, since this is a fictional technology (to a point), discussions of how it works are a certain degree conjectural.

However, in any large and complex engineering environment, catastrophic cascade failures can happen. Doubly so in something that moves around and which may be exposed to various radiations, forces, and/or collisions with other bodies.

I wanted to address this, as I have some experience in fission.

A fission reactor plant is essentially a giant hot water heater. And as such, the reactor gets quite hot. This is cooled, and the heat from the coolant is used to spin steam turbines.

Now going to our (mythical) fusion reactor, we see one major difference. First off, we are feeding it fuel. Shut the fuel feed off, and the reaction dies. You can't do this in a fission reactor, because all the fuel the reactor will use in its lifetime is already present.

Second of all, it requires enormous pressure (or equivalent) to generate a fusion reaction. Release that pressure, and even with fuel in place, the reaction stops. This can be as simple as a relief valve, or if it uses some electronically generated means, a simple circuit breaker.

So either way, a fusion reactor should be quite simple to design such that it will not overheat, melt down or release large amounts of uncontrolled radiation. Break the reactor vessel, and the reaction stops due to loss of pressure. There may be some secondary activation, but that would be confined behind the regular shielding one would need for the reactor in the first place.

Its a lot harder to fuse hydrogen than it is to get uranium to fiz (?) which means that stopping a reaction once it starts should be fairly simple.

 

[Drakon]

I find I have to agree with Anthony here. If you are at the corner of No and Where, a lifeboat is going to do nothing but prolong the time you have till you die. Not in any meaningful sense, because with no one to rescue you, you are still dead.

Unless it is jump capable, which means a minimum of 100dtons and is in effect another starship.

Perhaps you are thinking that it will get you to the surface of a planet. But this assumes you are close to a planet that will support your life. Except for deep space reconnance, or scout mission, this means either A) human starport nearby. or B) being marooned with little more than the clothes on your back. Not a good option.

If you are someplace else, Some and Where, there are other vessels around that can lend assistance. Where are they going to look? Where your ship is, not where the myriad lifeboats went. (At best, they will start their search from the ship.)

Most of the casualties you can come up with result in either the immediate death of all hands (decompression, etc.) or, if not, cripple the ship. If the ship is crippled, fixing it is a far better option than waiting around to die separated from the ship.

It is not a matter of "if everything works, then these are unneeded" so much as even if everything fails, the lifeboat buys you nothing, except more time to write a will that no one will read. Lifeboats cost in cargo space, and ability of the ship to prevent exactly the disasters one would need a lifeboat for.

It really does come down to a risk/reward kind of calculation. At worst, they aren't used because you are dead anyway. At best, you are waisting time you could be used for repairing the ship.

It should be noted that lifeboats were originally designed for a particular kind of vessel. One that sank. That is a problem we don't have in space.

Also, in answer to the submarine question. There is no lifeboats or escape capsules. If the hull is breached, you are dead anyway before you could get to the surface. And if you are in the artic, you are dead in the water in like 4 minutes, supposing you survive to the surface without the bends, or your lungs going *pop*.

There are escape trunks, which will allow egress from a sub if it is sunk (and unable to come back up) in less than 200 feet from the surface. But considering where subs usually operate, this is very rare, and usually close to some port. So again, no lifeboats are needed. Because they would do the crew no good.

[DSRV have a limited depth, and require the boat to be more or less stationary. Meaning sitting on the bottom. Considering the depth of much of the ocean, far in excess of DSRV's depth, they are useless for the most part as a rescue vehicle.]

 

[Andrew Boulton]

The best "lifeboat" might be enough low berths aboard the ship for everybody, with their own dedicated power plant. Doesn't matter if it takes a week, month, or a year for help to arrive, they'll still be fine.

 

[Pwyll]

thanks anthony and drakon, you expressed it more clearly than i

i not sure if i like andrew's idea. it seems more sensible than creating a separate vehicle to stick the low berths into, and situations where "sleeping it out" is the solution would be rare to the point that only ships in special circumstances would devote to space to it. might be a better solution to bring extra ships instead, hehehe.

 

[kaladorn]

A lot of this discussion is predicated on your assumptions about technology, development, and level of civilization.

There are *a lot* of places in the Imperium with D or E starports, maybe no SAR facilities, maybe very little traffic, maybe low tech on the local planet to prevent a local off-planet capability, and where a ship carrying passengers might end up having a serious problem. If this was a 2300 AD universe, with everyone having TL12 on all colonies, then maybe I'd agree with you. But it isn't. And some starports may just be beacons and a pad. No SAR.

Secondly, your comparison with subs is apples and oranges to some extent. The problem with escaping a sub is the pressure issues. If we could build a safe way to escape a sub for a reasonable cost (and traveller lifeboats are, especially with the original designs posted here), we would. But we can't. The same is not true in space. And we do have the equivalent of sinking - a catastrophic event that forces the evacuation of the ship.

The purpose of original earth nautical lifeboats was to allow crew of a sinking ship to abandon ship and sail to shore (jump lifeboat). The purpose of today's lifeboats is to abandon ship and to wait around for rescue. That's the Traveller lifeboat without jump in a system with some method of picking them up (or where they can, using their weak engines, fly to a habitable planet). Plenty of these places exist even within one sector of the OTU. So to me, the logic still applies.

As to the comments about fusion: Do we know how they're doing it? Do we know it isn't some bizarre cold fusion or some oddball process using gravitics? Your theories on how to damp out the reaction make sense - restrict the fuel, cutoff the enhanced pressure. However, that presumes these systems work! If they fail to (fuel inlet sticks on, or perhaps grav controller malfunctions, or system is sabotaged), you may NOT have the correct function and you may well have an issue thus needing to abandon the system. Plus, in order to generate this pressure and to feed the fuel, we run machinery that may (since we have no idea how they generate the pressures, I'd guess massive grav) well have a high heat radiation and thus cooling is still necessary, thus coolant leaks are still possible.

And there are lots of other flammable and combustible components aboard ships which could cause problems. Probably bio-contaminants as well.

I come back to the point that lifeboats are there for the purpose of saving lives when unpredictable catastrophe overtakes the ship. Full stop. They may have to go into a cold sleep capsule in the lifeboat, who knows. But such situations occur (or do conjecturally, since this is all a conjectural situation).

Also, re subs: Most are military or exploratory, thus not 'passenger carrying'. That makes a big difference to level of assumed risk and the required safety technologies. Even small planes and ultralights are starting to have CO2 launched parachutes created to set them down gently when engines fail....

Keep in mind also that the lifeboat offers wonderful RPG gaming possibilities, for interesting story lines, etc, that an excess powerplant will not. Thus, for that reason alone, I'm inclined to think they should stay.

 

[flykiller]

I find I have to agree with Anthony here.

if you like, but so far the case against lifeboats consists of best-case assumptions for itself, and worst case assumptions for the lifeboats.

it uses best-case assumptions for itself in that it assumes that comms are still available, that critical repair personnel are still available, that parts are still available, that fuel is still available, that major catastrophic engineering failures do not occur, that no failure puts the ship in an imminent unsafe condition (i.e. collision or decaying orbit), that there is no time limit to any particular repair, and/or that whatever failure occurs is either fixable or simply unsurvivable from the get-go. none of these assumptions are warranted.

it uses worst case assumptions for lifeboats in that habitable destinations are said to be either nearby and able to assist, or are non-existant. again, neither assumption is warranted.

designing a ship to be robust is good (the scout cruiser already has a machine shop), but the case against lifeboats is unrealistic. lifeboats provide options when all the assumptions fail.

 

[Anthony]

I will admit that there _is_ a certain value to having a shuttlecraft on board; that is, in a sense, a lifeboat. If your ship is crippled above a world with a class D or E starport, taking a shuttle down to the world makes sense. Also, shuttles are useful for lots of things other than lifeboats. However, you don't need long duration on these shuttlecraft; for that matter, you don't even need enough shuttles for everyone on board. Crippled ships don't tend to go anywhere interesting, you'll have time to make multiple trips.

 

[Andrew Boulton]

There are *a lot* of places in the Imperium with D or E starports, maybe no SAR facilities, maybe very little traffic, maybe low tech on the local planet to prevent a local off-planet capability, and where a ship carrying passengers might end up having a serious problem.

Large, passenger-carrying ships are not going to be going here.

And we do have the equivalent of sinking - a catastrophic event that forces the evacuation of the ship.

Which doesn't kill many people, and gives you long enough to get everyone into boats.

 

[kaladorn]

Originally posted by Andrew Boulton:
Large, passenger-carrying ships are not going to be going here.

Imperial Astrography 101, friend Andrew. Oft times you have to pass through these backwaters to get to where you want to go, especially with a J1 or J2 liner. So, yes, they *will* be going here, though not as a destination. Still, the fact they pass through these systems and refuel there may well result in a situation requiring evacuation.

Which doesn't kill many people, and gives you long enough to get everyone into boats.

Oh?

It might, or it might not, kill many people. As for time to get into boats, there could be 1 day, 1 hour, 1 minute, 1 second.... who knows? It depends on the particulars of the situation. If you have 10 minutes to fill your boats, you might get a fair portion of the passengers off... maybe. or not. You still design for getting 100% off. I can just imagine the ad campaign that says "We've ensured that we have 120% lifeboat capacity! Our competitor has 50% capacity! Do you go with us where you are gauranteed to have a spot, or with them where you flip a coin?".

The other poster said it most clearly: The arguments being advanced for the uselessness of lifeboats presume upon the lack of a worst-case scenario for the ship and the worst-case situation wrt lifeboat use. I too believe these are unwarranted assumptions.

 

[The Oz]

I don't think anyone has yet brought up what I feel is the most likely survival situation a TRAVELLER starship could find itself in:

Misjump that ends far away from any star system.

Now I understand that there's some debate about whether it's possible to come out of jump in the middle of nowhere, but even if you assume that ships require a mass to precipitate themselves out of jumpspace, there are always dark masses located in the deeps of space to serve as unwanted jump points.

If you come out of jump and you're out of jump fuel and a parsec or two away from the nearest inhabited system, you'll be very, very glad if your ship has low berths (emergency low berths or otherwise) enough for the entire crew and passengers aboard. These low berths can be part of the ship or part of lifeboats but you'll want them.

I imagine the procedure would be to send a radio message to the nearest inhabited system asking for help and then you throttle the powerplant down to minimum and everyone gets into the low berths and you wait and hope. I don't think you'd try to make it to the nearest star system yourself. If you have the maneuver fuel to do it before you can expect rescue you just might have enough to jump there and be done with it. If you know that no rescue can come before your powerplant fuel is exhausted you probably don't have the fuel to make it there on your own, either.

That's one of the few things I like about the MT starship design rules: you get the power consumption for everything and you can figure out just how long the powerplant fuel will last if the only things powered are the low berths.

So perhaps the important thing is to have enough low berths for everyone, either onboard or in your lifeboats, if you feel you need them.

 

[Rupert Boleyn]

Originally posted by Anthony:

How many people actually fit in a 20 dton lifeboat anyway?

I whipped a couple up for HG2 last night using HGS. Using a bridge you can get 28 people in (seated in couches), which should include a pilot and a medic. Using a computer/1 (probably a good idea as that means you could add basic autopiloting programs, etc.) you can get 32 people in, including pilot and medic. The first version cost a little over MCr7, the latter about MCr10.

The passenger couches could be replaced with low-berths for about MCr0.75 and no loss of capacity. Using emergency low-berths doubles capacity and means that if only 13 or 16 people (depending on whether there's a bridge or a computer) are on board they can be concious.

 

[Pwyll]

well, maybe i WOULD want to tuck a lifeboat into my cargo hold if i was regularly flying around in systems that have worlds with breathable air and no provisions for space rescues. i guess that would be mainworlds with E class port and atmosphere 5, 6, or 8. i certainly acknowledge places like this exist within imperial territory.
outside the imperium too, proly in somewhat greater numbers.

not everyone flies there tho....

my point is not that a commercial ship should never carry a lifeboat, but that most don't have the need for it because of their routes.

now, if my ship is real big and i have lots of passengers, maybe sticking a boat in the hold isn't the best solution so i'll acknowledge that big passenger ships flying around in the aforementioned areas proly ought to have the lifeboats designed in. i don't imagine that E class ports are high on anyone's list of desireable ports , though, and stops that cut profit would TEND to be avoided by anyone whose profit margin is at stake.

as for folks needing a lifeboat instead of a lifebubble when rescue IS available,

don't be a wuss

kaladorn, IMTU lifeboats are as re-usable as any other craft. except for the holes they get in them when used to escape from pirates i would think that time is a factor in most piracy, so i really think a pirate would rather spend a few minutes transfering easily removed high value items (like vehicles) than spend hours removing stuff like the electronics from the victim. if the ship was apprehended prior to jump (rather unlikely for a pirate), of course, the ideal would be to take the whole ship. hope you brought a prize crew! perhaps time wouldn't be a such factor if no-one knew the victim has problems, but i have been using an old TAS article, Piracy in the spinward main (or something like that) to guide my views regarding piracy, which, IIRC, indicates that authorites are likely to be en route right away.
hijacking is a substantially different type of threat (it comes from within the ship), and i don't really think lifeboats would help against it. seems like folks would get shot at (or even hostaged) while wandering to and fro in search of lifeboats during such violent happenings. not that cowering in a stateroom waiting to be spaced by victorious hijackers would be better. tough choice. lifebubble would still be just as good as a lifeboat in this case too, i think.

so, maybe a lot of ship designs have spurious subcraft

cargo capacity rules! let those who have the need, stuff a lifeboat in it. but as far as DESIGNING my fat trader or liner with vehicles, no

as for anyone who feels that i am maximizing my point and minimizing yours, well, yeah

now its your turn to do the same thing (again)

sure is fun discussing this

 

[Pwyll]

i am curious to know how many folks actually HAVE used lifeboats or even lifebubbles in games, and what their game experiences were

 

[MrMorden]

A sealed ATV or pressurized air/raft can make a fine lifeboat.

 

[MrMorden]

Originally posted by Pwyll:
i am curious to know how many folks actually HAVE used lifeboats or even lifebubbles in games, and what their game experiences were

I usually have lifebubble in my game, but the only lifeboats are whatever small craft are already onboard...dedicated lifeboats are too expensive and the number of circumstances you'd use them too few.

Most of my air/rafts are pressurized, and they work well as a lifeboat in a pinch if the ship simply cannot support life anymore. If you're already in orbit you can even land in one.

A vac suit can get you down safely also, if it has an EVA maneuver unit and an ablative reentry shield.

My lifebubbles are a heavy backpack-sized unit. They contain an O2 scrubber and a radio beacon, and a small flask of water and a couple of food bars. They'll support one person for about 72 hours before the air starts to get bad, and two people can fit in one in a REAL pinch for about half as long.

Andy