Mating Airlocks to Cargo Hatches

[swordtart]

Generally speaking Class E Starports are in the frontier and very low TL which also means the atmosphere is breathable. And you don’t need an Airlock to depressurize your cargo bay to unload it most ships cargo bays are separate from the rest of the ship. The Marava has two cargo air locks and the Hero, Beowulf and Subsidized Merch all have separate cargo hold so they don’t need an air lock. I would say the latter 3 are good examples of why Airlocks are generally considered a waste of space on a trader.

Lets have a look in my part of chartered space, District 268. There are 9 systems with Class E ports.
Milagro requires a Vacc Suit
Datrillian requires a filter respirator
Talos, and 567-908 require a respirator
Dawnworld is dense but breathable
Faldor requires a filter
Flexos and Noctol require an air supply
Judice has a corrosive atmosphere and requires a Vacc Suit (likely a HEV Suit).

So the vast majority of class E ports require some sort of airlock to avoid damage, contamination or simply bleeding out the air supply. Only one is breathable without extra gear and even then you might suffer over pressure effects if you were not careful.

By separate hold you mean on some versions of the deck plans a hatch has been arbitrarily drawn. Which could be added to any ship at no cost since it is just an icon. But if you want to expose the entire hold of your subbie to who knows what and spend the time depressurising and repressurising it (so you can have a shirt sleeve atmosphere that some people seem to think should be normal) there is nothing saying you can or you cant.

Whether you think it is a good idea or not depends on how you intend to use your ship. You get one airlock free for every 100 tons or part thereof (which take up no space apparently since it isn't listed against their capacity). Extra ones are a minimum 2 ton but there is no stipulation on how big a cargo one needs to be and there no reason that you cannot make it up from the free ones so a 400 Dton ship could have 1 passenger airlock and up to 3 designated as cargo (or presumably that could be replaced by one big one that is three times the size). Even if you paid extra for a cargo airlock what does a 10 Dton lock mean. It takes up 10 DTon, but can it hold 10DTon of cargo in the lock. If so you aren't really giving up the space for it as you can always store some cargo in the lock itself*. You have to pay a little for it, but that seems a small price to play for the flexibility.

Seems a lot of fuss over something that is largely glossed over in the rules.

* which is functionally the same as a cargo bay with cargo hatches - as this is also an airlock according to HG p25

 

[tytalan]

Free airlock are 2dt they can not be anything else because if they can be any size it breaks HG design rules ‘see my 100 dt jump 4 merchant ship I have a 10dt cargo bay but my air lock is 500dt I use that for cargo’ that may be a extreme example but it should show clearly how allowing free airlocks to be more than 2dt can be abused.

If you want to redesign everything publish ship and do new deck plans go for it. Let me know when you have all those deck plan done and also make sure the free airlocks are only 2dt otherwise you just power gaming.

 

[rinku]

In regards to cargo transfer without a cargo airlock... the cargo bay IS the airlock. Any cargo too fragile to be directly exposed to the destination atmosphere conditions would reasonably be shipped in a protective container. Exposure to vacuum due to hull breach is a common enough possibility that I'd expect almost all cargo and freight would be shipped that way, unless there was some rare reason not to. And if you're making it vacuum proof you really cover the other atmospheres except Corrosive and Insidious.

But... a cargo airlock does give you options. And a buffer between cargo bay and hull... if the bay opens using a hull hatch, a hull breach affects the bay. If it's sited inside the ship with a access via a cargo airlock, it should be harder to get to. Even if the space combat rules don't drill down to that sort of thing, a boarding action played out on the deckplans certainly does.

 

[Vormaerin]

What we don't know is the cost differential between a "plain" cargo container and one rated to handle vacuum. If the prices are similar (which seems unlikely to me) then they'd totally use the better cargo containers. But would they be similar?

Just as a comparison, refrigerated cargo container IRL is about 5x as costly as a regular one. A differential on that scale or more can be quite prohibitive.

But, then we don't know what the cost differential is between keeping the cargo bay pressurized and warm compared to not doing so, since Traveller doesn't assess life support costs in that way.

The sad fact is that, for all the jokes about Traveller being about ethically challenged traders, Traveller has never paid the slightest attention to anything about the process of trade. There's no information about how the interior of ships is actually loaded. Or how they are unloaded at those Class D & E ports. There's no thought put into what the actual status of the cargo hold during transit is. Or what cargo containers are like, beyond that they exist.

There's little to no thought about the different kinds of cargo having different requirements. IRL, completely different ships handle liquid cargo, bulk cargo, containerized cargo, uncontainerized cargo, and other categories.

Traveller just has "cargo hold". Sometimes they have airlocks, sometimes they don't. Sometimes they have gantries, often they don't. In theory, they could have cargo loaders of some sort, but that's pretty rare.

You kind of just have to pick your own assumptions about how things work and build up from there. Which some people like and some people hate.

 

[rinku]

Occam's razor says that common shipping hazards are taken into account in how you ship freight.

Ocean going ships and flatbed railcars need weatherproof cargo. Fragile airfreight needs to be in a suitable container. Even if a pressurised hold is expected, that can go wrong and you'd be well advised to address it with the packaging.

Freight often travels by various carriers and is usually only removed from the shipping container at destination. So I'd have thought it simpler and cheaper to have a robust default standard that can deal with vacuum, weather, and the less extreme atmospheres. Possibly it would provide some degree of Rad protection, although spaceship hulls do most of the heavy lifting there.

Containers also have to be robust enough to be moved under load. That likely goes a long way towards "might as well make it airtight if it's going into space".

 

[Vormaerin]

Again, that depends on factors we know nothing about. A container that can survive the temperature and pressure extremes of vacuum is probably not cheap. Whether it's cheaper than an expectation of pressurized holds? No idea.

Not to mention, if vacuum holds are the norm, special containers with their own life support will be necessary for all goods that can't actually survive the cold, the lack of air pressure, and other factors involved in being in space. Of course, a lot of those things require power and life support hook ups. Unless we are going "all the containers have a Fusion+ system!" or something like that, then the cargo hold has to have a lot connections so whichever containers need power & life support can get it once the hold is depressurized.

Containers today are robust enough to be moved under load. Or I don't understand what you mean by that.

Only about 60% of oceanic freight at the current time is containerized freight by volume. Bulk liquids and solids like oil, water, grain, & minerals all have their own specialized types of ships that are nowhere to be seen in Traveller, because that's not the sort of ship a PC is expected to be operating.

Of course, the speculative goods table has oil, live animals, bulk ore, and typical containerized consumer goods all piled up together. Containerized petrochemicals would be super inefficient, but I guess we could be doing that. And fancy full life support space barn containers for the live goods.

So, essentially, every starport has to have stocks of all these specialized containers. Or they are shipping empty space barns back to their ag world homeland because the asteroid world doesn't have any live goods export.

Or maybe the predecessor of the Personal Energy Shield was a Cargo Energy Container that can conform to any configuration needed.

The actual logistics of trade are not worth the effort of trying to resolve. If Futuretech Space Containers in depressurized holds works for you, that's an entirely reasonable simplification for something so tangential to gameplay. Traveller in general certainly puts even less thought into it than that.

But there's also a fair number of references to crew accessing the cargo hold during transit and some ships have cargo holds in places that would be pretty awkward if they were depressurized and the crew spaces on either side weren't, IIRC. Though most ships have been through enough variations in floor plans that I can't recall if that's true of any of the current edition versions.

As I said. Pick something that you like and run with it. Which might be "who cares?" or it might be inventing house rules for bulk freighters, space tankers, and all the rest There's no answer in the setting materials and not enough information to even pretend to derive one.

 

[swordtart]

Free airlock are 2dt they can not be anything else because if they can be any size it breaks HG design rules ‘see my 100 dt jump 4 merchant ship I have a 10dt cargo bay but my air lock is 500dt I use that for cargo’ that may be a extreme example but it should show clearly how allowing free airlocks to be more than 2dt can be abused.

If you want to redesign everything publish ship and do new deck plans go for it. Let me know when you have all those deck plan done and also make sure the free airlocks are only 2dt otherwise you just power gaming.

I can add cargo hatches at no cost or space.
I can add pressure partitions at no cost or space.
I can add inter compartment hatches at no cost or space.

A pressure partitions plus a cargo hatch equals an airlock according to HG.

I have added 2 cargo airlocks to every ship in HG. The designs are unchanged in HG format, just add the words cargo airlocks to the ships published in HG. Deck plans are exemplars so you can make your own.

 

[Vormaerin]

Exactly. The game essentially says "we don't care about this, do what works best for you." The only reason there is a rule about airlocks at all is probably because someone was like "I'll put an airlock in every stateroom!" and the designers were like "Fine, no, you can't".

The same reason that they don't care about the very significant differences between liquid/gas bulk, dry bulk, breakbulk, RO/RO, containerized, and a few other types of freight. And it doesn't care how you get your ship unloaded on the E port planet.

Personally, I think that PC type tiny trade ships doing tramp trading in small to non-existent ports are going to be primarily handling breakbulk cargo (and possibly RO/RO if you have a suitable cargo hold like the Fat Trader does) and having some kind of Alien style loader exoskeleton or two. Though you could imagine some kinds of anti grav doohickeys to make containers feasible. Either way, the loader or the grav sled thingies are not actually mentioned in ship design.

 

[Condottiere]

If you manufacture containers from spacecraft hulls, they will likely be vacuum proof, life supported, and climate controlled.

Likely, options descend from there, with a twenty foot new steel container costing, inflation included and/or adjusted, two hundred credits?

 

[Vormaerin]

Assuming you gave them a power plant to actually provide that life support.

And you can invent whatever number you like for the cost of containers, because there's nothing to base it on.

 

[swordtart]

If you manufacture containers from spacecraft hulls, they will likely be vacuum proof, life supported, and climate controlled.

Likely, options descend from there, with a twenty foot new steel container costing, inflation included and/or adjusted, two hundred credits?

The per DTon cost of an unpowered non-gravity hull is set out in HG there is no need to speculate.

 

[Condottiere]

Actual shipping containers.

Which do need the protective environment of an internal cargo hold.

 

[Vormaerin]

A basic steel 40' shipping container runs about US$5k in my neck of the woods, but you can buy used ones for as little as US$1500 or so. Refrigerated ones are usually closer to US$25k new.

What it would cost in a future with fabricators and other fancy tech, no idea.

 

[Condottiere]

Retail seems to vary with current demand.

I looked up Alibaba to see what's the current going rate down there.

 

[mavikfelna]

Battery tech in MgT is pretty good. Fuel cells and the like also exist. So a cargo container that is self powered but needs to be recharged every other week or so might work well for containerized cargo that needs environmental support. Should be reasonable cost wise. Of course now we have to start paying attention to the TL of container.

 

[J. L. Brown]

Battery tech in MgT is pretty good. Fuel cells and the like also exist. So a cargo container that is self powered but needs to be recharged every other week or so might work well for containerized cargo that needs environmental support. Should be reasonable cost wise. Of course now we have to start paying attention to the TL of container.

Batteries in Traveller suck. If your hypothetical 'recharge once per week' container uses just one Power, then (at TL-12) it requires a minimum of 28 dTons of battery for 5.6 MCr.

If you manufacture containers from spacecraft hulls, they will likely be vacuum proof, life supported, and climate controlled.

And quite expensive. Even buying 'non-gravity' hulls this means paying 25 KCr per dTon. Since a Credit is supposed to worth multiple (modern day, US) dollars, this approach leads to 'sea-freight container analogs' which cost several orders of magnitude too much. Also, per the SOM, the basic 'cargo container' in routine use is not assumed to automatically be vacuum-tight.

Free airlock are 2dt they can not be anything else ....

This statement is NOT supported by the text. There are multiple examples, being too numerous to list here, where things which are bought by the dTon are combined into larger groups on the deckplan. HGU p 58 says only:

Airlocks consume a minimum of two tons ....

 

[swordtart]

Exactly. The game essentially says "we don't care about this, do what works best for you." The only reason there is a rule about airlocks at all is probably because someone was like "I'll put an airlock in every stateroom!" and the designers were like "Fine, no, you can't".

I think you may be right and I am not even sure why you would even want to stop that.

The same reason that they don't care about the very significant differences between liquid/gas bulk, dry bulk, breakbulk, RO/RO, containerized, and a few other types of freight. And it doesn't care how you get your ship unloaded on the E port planet.

All remaining empty space is Cargo space. It doesn't cost anything to designate empty as Cargo space (as opposed to say Common space) and the as you say the configuration is irrelevant.

Personally, I think that PC type tiny trade ships doing tramp trading in small to non-existent ports are going to be primarily handling breakbulk cargo (and possibly RO/RO if you have a suitable cargo hold like the Fat Trader does) and having some kind of Alien style loader exoskeleton or two. Though you could imagine some kinds of anti grav doohickeys to make containers feasible. Either way, the loader or the grav sled thingies are not actually mentioned in ship design.

If trade goods or freight came in sub DTon quantities it would be nice. Though I suppose that as it doesn't come in Lots (like it does in GURPS Far Trader) there is nothing to stop you buying half a Dton of something. I also suppose you might ship fractional DTons of freight for a proportional cost of a full DTon.

 

[tytalan]

This statement is NOT supported by the text. There are multiple examples, being too numerous to list here, where things which are bought by the dTon are combined into larger groups on the deckplan. HGU p 58 says only:

No it’s supported by common sense and the desire not to break the game. Like my example a 100dt ship with a 500dt airlock for cargo if you give it infinite free dts you break everything. Now I would agree that multiple 2 dt free airlocks could be combined but that 2dt is built into the design system and works for the game balance. infinite free dt for the free airlock is as broken as can be

 

[Condottiere]

First of all, determine what you're actually shipping.

If it's not a lot, and you have them on a pallet, that's a doorway.

You will have tied them down, but inertial compensation should ensure they stay in place.

 

[swordtart]

No it’s supported by common sense and the desire not to break the game. Like my example a 100dt ship with a 500dt airlock for cargo if you give it infinite free dts you break everything. Now I would agree that multiple 2 dt free airlocks could be combined but that 2dt is built into the design system and works for the game balance. infinite free dt for the free airlock is as broken as can be

Who even suggested that?
Your 400 Dton ship can have 4 free 2 Dton Airlocks. Or 4 free 2DTon cargo airlocks. Or one 8Dton cargo airlock.

If you want any extra airlocks of any type they needs to be taken from the hull capacity as I explicitly stated in my post. You cannot have a 500 Dton component of any kind in a 100Dton ship, suggesting otherwise is pointless sophistry.

Only you have mentioned infinite free airlocks.

I am going to disengage now as you are clearly just trolling.