General Math Sucks: Cargo Containers
- Thread starter Rigel Stardin
- Start date
If you go with my postulated cheap pressurized vs space capable, TL6 could handle making the cheap ones, TL 8+ minimum for the space versions. The latter suggests starport B and up, I’d probably go with can’t be non-industrial (too much a side thing for populations that have to focus on their main living/export trade).
Condottiere
SOC-14 5K
Technological level nine is self sealing, though twenty five kay starbux per fourteen cubic metres is definitely too expensive.
The standard shown in CT's TTA is 3x3x6m, FYI. That's 4 Td per container.
TTNE gives us 10 tons mass per dTon as the default for not recalculating the drives. Most frieghters can use that assumption.
Mega gives us 1 tonne (mass) per kl for cargo space and 13.5 kl per Td...
Once GDW endorsed the displacement ton standard (by the time TTA was being written), they doubled down on it.
Exploit the cube/square law by making them bigger. The empty space on the inside is free; it's the bits around that empty space that you get billed for
Condottiere
SOC-14 5K
It's basically ungravitated default spacecraft tonnage, but it does get pressurized and life support.
Spinward Flow
SOC-14 1K
Which is unintentionally hilarious because major cargo is supposed to be 10 tons (per block), minor cargo is 5 tons (per block) and incidental cargo is 1 ton (per block). So the 4 ton "standard container" specified fits NONE of those criteria cleanly unless dealing with multiples of 20 tons.
3x3x1.5m would yield a 13.5m3 1 ton container that could be used for incidental cargo (2x1 deck squares, full deck height).
3x3x7.5m would yield a 67.5m3 5 ton container that could be used for minor cargo (2x5 deck squares, full height deck).
3x6x7.5m would yield a 135m3 10 ton container that could be used for major cargo (4x5 deck squares, full deck height).
After that, everything is a game of Tetris/Inverse Jengha to fit stuff into the cargo hold until there's no more room for more.
Note that under such a system, cargo bay doors would need to be a minimum of 3x6m (4 deck squares wide, full deck height) in order to load and unload standardized major cargo containers.
And then you get to Modular Cutter Modules with their ROUND cross sections and you start having fun with the "square peg round hole" problem of standardized container shipping using rectangular blocks that only works with 2 major cargo containers plus 10 incidental cargo containers (and don't put the cargo access side door in the middle if you want to get stuff in and out).
Rigel Stardin
SOC-13
You guys are confusing me with how express the dimensions of the cargo container. Shouldn't it be Length x Width x Height? And if you are expressing them correctly, 4 Ton containers can only be carried on ships with cargo hold height of 6 to 8 meter? And wouldn't that mean, most independent trader would be knock out of the market because of this?
Spinward Flow
SOC-14 1K
Commutative property - Wikipedia
Rigel Stardin
SOC-13
I'm even more confused. Math was no my strong suit.Even if the 7.5 meters is the width or length, the other problem is: I've only seen two ships with higher cargo decks. The Empress and the Subsidized Merchant from the Spinward Marches Campaign book. Empress being 4.5m and the Subsidized Merchant being 6m. Every other design, I assume has a 3m cargo hold height? 3m cargo containers would not fit inside unless you use a crowbar or modify the hold.
AnotherDilbert
SOC-14 1K
Yes, standard decks are 3 m.
I assume when people say "3 m tall container", they mean "just shy of 3 m tall container, that can just slide into a 3 m tall cargo hold with minimal room to spare".
I assume when people say "3 m tall container", they mean "just shy of 3 m tall container, that can just slide into a 3 m tall cargo hold with minimal room to spare".
Condottiere
SOC-14 5K
Thirty five centuries should have allowed us to figure out optimal dimensions.
And it's less the tonnage/volume, more how those dimensions are configured.
Three metres is an assumption, based on deckplan squares, and should account for floor and ceiling, if not hull.
And it's less the tonnage/volume, more how those dimensions are configured.
Three metres is an assumption, based on deckplan squares, and should account for floor and ceiling, if not hull.
Condottiere
SOC-14 5K
I remember playing with my coloured wooden fishstick blocks in kindergarten, that one times one times two is a rather useful configuration, but one times one times four is more elegant.
L×W×H is indeed English customary practice.
The "öfficial" is a 4 Td container of 3×3×6m. Mention is made of smaller ones.
A 1 Td is likely either 3×3×1.5 or 1.5×3×3.
Note that actual containers are probably 2cm less in every dimension to allow for connectors and maneuvering space.
A 5 TD would be better than the canonical 4 Td... and is 3×3×7.5.
Note that actual deck to deck is 3.11m to get 14.0m³ canonical Td, and the canonical containers are only 13.5m³ per Td of cargo (54m³ for the canonical "4 ton" container.
Note also: GT, HT, and TTNE use alternate deck plan gridding... which in TNE leads to the deckplan squares being 2×2m, and 3.5m decktop to decktop, for 14.0m³ per Td. GT uses hexes, as does HT... don't have mine handy to check.
There are no optimal dimensions.
By definition you can't have an optimal, yet, generic specification.
The modern container is not designed around what can fit inside of it, rather it's designed to fit on our roads, on our trucks, on our railroads, and to have good structural integrity given the materials (i.e. steel) that it is made out of. Our containers are also "human" sized, like most things. Designed to be comfortable for, operated by, and maintained by 5 1/2 ft tall beings.
The ships came after the container. The cranes came after the container. The infrastructure came after the container. The existing infrastructure of roads and railways are comfortable fit for containers, but the later specialization of cargo handling, freight cars, tractor trailer rigs, etc. came later.
There is an optimal container size... it's whatever size most of your trade partners use.. Which is why the 2 TEU 8×8.5×40 foot container is the defacto world standard. The US started implementing it, others joined in...
Note, however, the TEU standard is deck-space defined... 8×20 feet. It's allowed (by custom, not regs) to run 4.5 foot to 9.5 foot tall, with a gross mass of 53,000 lbs (~24 tonnes)
My container (I own one) has a listed tare of 2350kg. (a bit heavy)... that's the weight of the empty container.
(Tare is the empty mass , marked so you can charge rental containers at content mass rates.)
Note, however, the TEU standard is deck-space defined... 8×20 feet. It's allowed (by custom, not regs) to run 4.5 foot to 9.5 foot tall, with a gross mass of 53,000 lbs (~24 tonnes)
My container (I own one) has a listed tare of 2350kg. (a bit heavy)... that's the weight of the empty container.
(Tare is the empty mass , marked so you can charge rental containers at content mass rates.)
Rigel Stardin
SOC-13
This is what I have been trying to say. A modern container weights ruffly a metric ton (1,000kg) but can carry 24 Metric tons in ruffly the same space as a 3x3x12m cargo container. So a container 1.5x3x3 should at least be able to carry 2 Meteric Tons.
Spinward Flow
SOC-14 1K
Road/Rail/Ship containers can "afford" to be relatively massive when empty so you can stack them into piles (on container ships, in sorting yards, etc.) and not pay a massive penalty for being heavy when empty.
However, weight is the enemy of aerospace performance. You'll note that relatively few TEU steel containers get moved by aircraft ... because the containers themselves are heavy and impose a considerable penalty on cargo allowance for an aircraft. A broadly similar principle ought to apply with respect to spacecraft and starships as well. For surface transport in a gravity well, cheap to construct but empty mass heavy containers is something you can get away with ... but that doesn't necessarily hold true when it comes to anything that requires lift force (aerodynamic, gravitic, etc.) to gain altitude. When it comes to flight, weight/mass is the enemy of performance.
In other words, the aerospace (as in air and space) context for container shipping is not 1:1 translatable to the ground context for container shipping. Much like how "flying cars" wind up not looking like ground cars ... the context requires different tradeoffs in the engineering.
However, weight is the enemy of aerospace performance. You'll note that relatively few TEU steel containers get moved by aircraft ... because the containers themselves are heavy and impose a considerable penalty on cargo allowance for an aircraft. A broadly similar principle ought to apply with respect to spacecraft and starships as well. For surface transport in a gravity well, cheap to construct but empty mass heavy containers is something you can get away with ... but that doesn't necessarily hold true when it comes to anything that requires lift force (aerodynamic, gravitic, etc.) to gain altitude. When it comes to flight, weight/mass is the enemy of performance.
In other words, the aerospace (as in air and space) context for container shipping is not 1:1 translatable to the ground context for container shipping. Much like how "flying cars" wind up not looking like ground cars ... the context requires different tradeoffs in the engineering.
Rigel Stardin
SOC-13
I counter that with: By the time Traveller takes place, new lighter and stronger material are being used, making the container lighter. They are air tight and space durable (unless you're shipping live thing or refrigerated good). So you can cram all the dry goods you want into that 12.15 cubic meter space created in a 1.5x1.5x3m Container. This is what standardization does.
Aerospace/Gravitronic: Grav thusters ends the need to be concerned about weight. It then becomes a Structural issue, If 1,000 kg (1 Metric Ton) is all a 1.5m by 1.5m then something is wrong with they way mass is used in the game. Because, I'm quite sure a shipment of 4 scout engines in a 60 ton cargo bay, would overload the structural limit set up by the game. It's okay to put a 9 metric ton engine in the space of say 3x1.5x3m in the engine room but not in the cargo bay for shipment? That tells me something is wrong.
Finally, I said this earlier as well. Game designer blur the lines between ocean going ships and airplane.
Aerospace/Gravitronic: Grav thusters ends the need to be concerned about weight. It then becomes a Structural issue, If 1,000 kg (1 Metric Ton) is all a 1.5m by 1.5m then something is wrong with they way mass is used in the game. Because, I'm quite sure a shipment of 4 scout engines in a 60 ton cargo bay, would overload the structural limit set up by the game. It's okay to put a 9 metric ton engine in the space of say 3x1.5x3m in the engine room but not in the cargo bay for shipment? That tells me something is wrong.
Finally, I said this earlier as well. Game designer blur the lines between ocean going ships and airplane.
1 TEU¹ of bay space is roughly 2.45×2.94×6.12m, allowing for the 9.5'high cube, and rounded up to the next cm, for 44.08m³, with an allowed 24,000 kg maximum internal cargo, 2331.5kg max tare, and max gross 26331.5 kg max FOB; the containers themselves are usually floor rated to 26,000 kg internal to max 28200kg loaded... but wait - that's not the total...
Each container is supposed to allow at least 5 deep vertical stacking, so they have to be stressed for the frame to handle about 141,000 kg. Note that some modern postpanamax stack upwards of 9 deep... for just shy of 254,000 kg on the frame... in theory. (In practice, it's possible to have latches.
Plus, some of the wells are 45', with bars that the containers can lock into at 2.5' in from the end.
So, for a more "realistic" container set... based upon the trade rules in Bk2.
Assuming the CT/MT/T4/T20/MGT1 1.5²m²×3.0m cargo Td (Tdc) is in fact different from the actual displacement tonnage (which is pretty much a fair implication of TTA's standard container for the March Harrier deck plan)... Assuming 2cm clearance, and 1cm walls/ceilings, and 5cm thick floors
| Tdc | Notional dimensions | Ext dimensions | Presumable interior dimensions | Tare | payload | notional TEU at 8×9.5×20 high cube |
| 0.25 | 1.5×1.5×1.5m 3.375m³ | 1.48×1.48×1.48m 3.242m³ | 1.46×1.46×1.42m 3.025m³ | 803kg | 1,697kg | 0.076 |
| 1t (tall) | 1.5×3.0×3.0m 13.5m³ | 1.48×2.98×2.98m 13.143³ | 1.46×2.96×2.92m 12.620m³ | 1834kg | 8,166kg | 0.306 |
| 1w (wide) | 3.0×3.0×1.5m 13.5m³ | 2.98×2.98×1.48m 13.143m³ | 2.96×2.96×1.42m 12.441m³ | 2598kg | 7,402kg | 0.306 |
| 5 | 7.5×3.0×3.0m 67.5m³ | 7.48×2.98×2.98m 66.426m³ | 7.46×2.96×2.92m 64.478m³ | 7208kg | 42,792kg | 1.531 |
| 10n | 15×3.0×3.0m 135m³ | 14.98×2.98×2.98m 133.029m³ | 14.96×2.96×2.92m 129.302m³ | 13790kg | 86,210 | 3.062 |
| 10w | 7.5×6.0×3.0m 135m³ | 7.48×5.98×2.98m 133.297m³ | 7.46×5.96×2.92m 129.827m³ | 12839kg | 87161 | 3.062 |
| 20w | 15.0×6.0×3.0m 270m³ | 14.98×5.98×2.98m 266.950m³ | 14.96×5.96×2.92m 260.351m³ | 24,417kg | 175,583 | 6.125 |
| Rounding | none | up to 1l | down to 1l | up to kg | none | 3 places |
I would allow loading 10 tons per Td, myself, based upon TTNE's recalculation threshold... with the resulting payload being max-tare.
Oh, and aluminum? cut the tare by about half...
¹: https://www.soytransportation.org/Stats/Containers_WhatsATEU.pdf
²: https://www.marineinsight.com/maritime-law/teu-in-shipping-everything-you-wanted-to-know/
