Cargo Bays & Container Sizes

[Tenacious-Techhunter]

It's all well and good to want to maximize usable cargo space... however, making cargo containers 1.5m cubed with 1.5m^2 grid spaces is a mistake. It's just simply impossible to pack and unpack a ship that efficiently, because there's no margin of error.

Instead...

Cargo Containers should be exactly 3 meters cubed (leaving 5.7ish Centimeters wiggle-room per side), and be assumed to take up a quarter dTon of space.

Large Cargo Containers are 660 meters cubed (leaving just over 9 Centimeters wiggle-room per side), and are assumed to take up 10x10x2 quarter dTons of space (10x10 full half-dTon spaces), and are more space-efficient than smaller containers.

Grav-bladders (bladders with a grav surface at one end to pull materials in past the friction) in the ceiling can store particulate goods (like oatmeal or gravel), or liquid goods (like water or corn syrup); theoretically, this recovers 3 cubic meters of cargo space for every 4 half-dTon spaces of cargo space; a dice roll should (or should not) be made to see how well the stevedores pack the bladder.

The remainder of the Cargo Bay can be flooded with water, mineral oil, or fuel, to prevent it from being completely wasted; a dice roll should (or should not) be made to see how well the stevedores pack the bladder.

 

[phavoc]

There has always been a little wiggle room in the sizing portion of things, so that 10dton container fits perfectly in that 10dton space.

Aside from that, containerization has proven it's merit over the last few decades as the most efficient way to transport anything that fits within it. Bulk cargos can also be moved in the same manner by modifying the container to be a liquid or bulk storage container. Which works ok for small amounts, but if you are transporting anything of volume specialized bulk cargo carriers are the best way to go.

 

[Tenacious-Techhunter]

"Perfectly" is part of the problem; there's no wiggle-room. You can't pick one crate out by itself.

Modern containerized cargo works because of the cranes being able to work over an open-topped space. Unless you have a starship that folds its cargo bay doors open to reveal the entire bay, you can't get that. Also, most cargo ships of this type only ship from one point to another point, and not points in-between. They don't have to unload some cargo here, and some cargo there, like a speculating trader navigating through space would. Which is going to have to be put in and pulled out by fairly crude forklift-like systems.

The bulk systems I described have more to do with recovering the space lost due to deliberate inefficiency in these standard designs.

 

[phavoc]

A free trader is a rough analog of a tint liberty ship. It's not built as an effecient cargo hauler from a load point of view. Even container ships stack their cargos. The difference is that a free trader can only carry a maximum of 8 containers at 10dton each, where a container ship on our planet could carry several thousand.

For the size and with the inefficiency built in its not a huge issue. A ship will be in port forth days, and it takes a few hours in a worse case scenario to fully unload a free trader and reload it. Most likely smaller ships are going to take on much smaller containers, or a healthy mix, which requires more time to move around, but still not a huge issue. When you can control gravity moving containers isn't that hard.

Plus traders can have a built in cargo movement system to speed that sort of thing. And this is why you have a designated cargo master who loads the ship based on what needs to be unloaded when and where. If UPS and FEDEX can efficiently load package trucks I'm sure space merchants in the 52nd century can too.

 

[Condottiere]

How many times are a free trader holds completely packed?

Should have enough room to open up the containers and find specific cargo.

 

[Tenacious-Techhunter]

For certain definitions of efficient, yes. What I'm proposing is that 12/13.5 efficiency by crates should be the maximum for single crates, and that technical workarounds are available. 88% efficiency is damn good, and insisting on better is unrealistic, given these crates should be able to be moved around for loading, unloading, and for inspection.

I'm essentially saying that there should be a default packing inefficiency by design, and for good reason; no one wants their cargo packed down to the mil, because when the cargo shifts during flight, friction makes it become inseparable! Speed of loading and unloading is irrelevant when you start risking having to cut the hull open just to get the first crate out...

 

[-Daniel-]

For certain definitions of efficient, yes. What I'm proposing is that 12/13.5 efficiency by crates should be the maximum for single crates, and that technical workarounds are available. 88% efficiency is damn good, and insisting on better is unrealistic, given these crates should be able to be moved around for loading, unloading, and for inspection.

I'm essentially saying that there should be a default packing inefficiency by design, and for good reason; no one wants their cargo packed down to the mil, because when the cargo shifts during flight, friction makes it become inseparable! Speed of loading and unloading is irrelevant when you start risking having to cut the hull open just to get the first crate out...

While I agree with the idea of what you are saying, I have to say it is a level of realism I just do not care about. Not trying to be a dork here, just saying that this is not a freight simulation game for me. I just do not see my game ever being so detailed as to worry about the space between containers. If the players do manage to get a full cargo hold, we will just assume it includes space.

As for saying the shape of a standard, I am going to take a page from the airlines, there are several "shapes" and when combined, manage to fill the space allocated for freight. I suspect I will end up just having a few standard sized containers and not worry about it beyond that. 1/4th ton, 1/2 ton, 1 ton, 5 ton, 10 ton 25 ton etc. When you agree to take the 5 ton container I will not demand you prove you can fit it in the cargo hold that is half empty. You just do. On to the adventure.

 

[Tenacious-Techhunter]

I respect your apathy, but I think it would be better served with "guaranteed to work" rules like this. If players want to figure out how to get that extra 11% of cargo space, they're playing a different game than you, so better to default to a model that always works, I think.

 

[phavoc]

How many times are a free trader holds completely packed?

Should have enough room to open up the containers and find specific cargo.

Good question, and who knows? Depends on the dice gods I suppose. Even regular freighters, excepting many bulk cargo carriers, rarely travel 100% full.

For certain definitions of efficient, yes. What I'm proposing is that 12/13.5 efficiency by crates should be the maximum for single crates, and that technical workarounds are available. 88% efficiency is damn good, and insisting on better is unrealistic, given these crates should be able to be moved around for loading, unloading, and for inspection.

I'm essentially saying that there should be a default packing inefficiency by design, and for good reason; no one wants their cargo packed down to the mil, because when the cargo shifts during flight, friction makes it become inseparable! Speed of loading and unloading is irrelevant when you start risking having to cut the hull open just to get the first crate out...

It's not really needed. But, having worked in cargo and air cargo, I can tell you that with just a little bit of cleverness a great deal is possible. Air containers are designed with angles while an aircraft body is cylindrical. So they actually fit with a lot of 'waste' space inside. But inside, once they are positioned, they are easily locked into place with very little wasted space. Often its more about the weight than the volume - though not always obviously.

As for moving cargo efficiently in and out, many air loading docks for air freight containers are covered with wheels, allowing one or two persons to manhandle multi-ton containers easily across the floor to wherever they need to be located. And when you want the container to stay put you merely retract the wheels and its not going anywhere.

In a starship it would be quite easy to have deck plating with places to anchor a container just in case you lost gravity. If you've ever seen sea going container ships you'll notice that the containers are more or less stacked on top of one another, and they lose them all the time to rough seas - generally those on the stern where the support structure is the weakest.

It's easy enough to allocate a few inches for the containers to fit jjjuususttt right inside. Plus when you have control over the gravity it makes moving them around a cinch. FAR easier than when you gotta manhandle them. And with just two guys you can make short work of moving containers around to get to the one in the back that you need. But again, this is where a smart loadmaster earns their keep and organizes the containers based on when and where they need to be off-loaded. It's easy-peasy once you get the hang of 'the impossible'. That's true with cargo, or camoflage netting... many things become clearer the more you work at them.

'cept math. fooey!

 

[Tenacious-Techhunter]

Right, but those "wasted inches" have to come from somewhere. Better to bake it into the cargo container model. I don't think 2 inches per regular container, and 4 inches per large container, is too much. Plus, it's the nearest convenient value; 1.5m^3=3.375m^3; we're just rounding that down to 3 cubic meters, an easier number to math cargo with, and calling the excess "wiggle room and container material".

Effort of loading and unloading a single unconstrained container is not the issue; it's unloading it when there's no wiggle-room, and the proximity to other containers prevents extrication.

 

[phavoc]

That's true. But we are just abstracting the idea here. In reality the 1-2% volume you'd be giving up to construct a proper hold would be a factor. But from a gaming perspective it's not terribly important.

If you were going to build this into an adventure somehow then it would become more important because it could become a plot point. Thus far, in all my gaming experiences, fitting the containers into an exact space hasn't become a plot point. Not to say that it couldn't, wouldn't or shouldn't... just that it never has.

I'm all for patterning things in a logical manner, so believe me, I do understand your thought processes here. However I just don't find it to be of any critical sort of nature from a gaming perspective. If we were to hyper-detail out this, we should also do the same for all spaces within the hull, so drawing the deckplans out to squeeze in everything that would be needed would also be necessary. And while I appreciate the detailed effort, I just don't think it's an issue that needs much attention.

 

[Tenacious-Techhunter]

The point is to be never able to fit the containers in exactly. It's a sort of Imperium hedge against cargo shippers accidentally outsmarting themselves. The same is important for players, as well.

If cargo numbers are being redone, now is the time to make this sort of recommendation, so they match the containers being suggested. I think it's better that the rules that players default to be realistic, even if they don't need to know it. If players know that cargo is listed in cubic meters, and there are 3 cubic meters to a container, and 4 containers to a dTon, then they get realism for free. That's what I'm advocating.

 

[Annatar Giftbringer]

My reasoning for cargo containers, as well as vehicles, is that the dTon requirements are not the exact measurements of the item in question, but the amount of space they need, with a bit of free space around them for maneuvering and moving them.

A 3 dTon ground car could be assumed to take up 2x3 squares, but few cars are three meters wide or tall, that's the parking space needed, so the driver and passengers can enter/exit the vehicle and so on.

I imagine the same being true for cargo containers. A 4 dTon box isn't quite 6x3x3 meters, but that's the volume it needs, with the actual container being slightly smaller.

 

[phavoc]

There's always been a bit of wiggle room when it comes to Dtons. I've been ok with this because I haven't yet come across a reason to change. But I'm always open to new ideas.

 

[Tenacious-Techhunter]

Yes, but when you're buying bulk cargo, you can no longer use this itemized approach, because larger containers are more efficient than smaller ones. It's better to specify a volume that the containers contain, one that accounts for wasted space, and use that for your bulk cargo numbers than the raw dTon values.

 

[phavoc]

Yes, but when you're buying bulk cargo, you can no longer use this itemized approach, because larger containers are more efficient than smaller ones. It's better to specify a volume that the containers contain, one that accounts for wasted space, and use that for your bulk cargo numbers than the raw dTon values.

Well, bulk cargo (and depending on the volume...) usually moves best in vessels designed for it.

Standardization does make for increased efficiency - just look at how efficient the container market is. Thus far the most efficient design to move cargo has been the standard shipping container - that has right angles. If your cargo holds also have right angles you can slide them in, stack them, etc, all without issue. Triangles don't stack too well unless you are rotating them. It would be far easier to stack 4 rectangular containers on top of each other than 4 triangle-style ones, no?

 

[Tenacious-Techhunter]

Yes, but there are limits to that efficiency, and those limits should be reflected in the rules, in a mathematically convenient way. Hence, my drop from a quarter dTon to 3 cubic meters.

I never said cargo would be triangular; I said the structure of the hull's spaceframe would be triangular. Cargo can afford the weight inefficiency of using right-angled panels, presumably composed of coated carbon foam.

Cargo containers cannot slide past one another without adequate clearance. Dropping the volume down to a convenient 3 cubic meters provides that clearance, whereas there was an unrealistic 0 clearance and 0 inefficiency before.

 

[phavoc]

Yes, but there are limits to that efficiency, and those limits should be reflected in the rules, in a mathematically convenient way. Hence, my drop from a quarter dTon to 3 cubic meters.

I never said cargo would be triangular; I said the structure of the hull's spaceframe would be triangular. Cargo can afford the weight inefficiency of using right-angled panels, presumably composed of coated carbon foam.

Cargo containers cannot slide past one another without adequate clearance. Dropping the volume down to a convenient 3 cubic meters provides that clearance, whereas there was an unrealistic 0 clearance and 0 inefficiency before.

Hrm... I suppose you could do that. For the angular portions you could use them to store fuel and such.

You are right in that the displacement is a 1:1 relationship. The hand-wave of 20% over/under on the deck plans allowed for the visual changes. Which is ok with me since we aren't trying to make architectural drawings, just visual representations.

With the rounding that is present in the Dton calculation you could probably find the clearance you need. Which I can tell you from experience needs to only be a few inches in reality. More is nicer, but not a necessity. Still, you have a valid point here if you are trying to better model the realism. I just don't see this changing all that much because the return on the changes doesn't seem enough to justify it (my opinion).

 

[Tenacious-Techhunter]

5.7 centimeters already is "just a few inches"; just under 2 and a quarter inches; not counting the thickness of the crate walls, of course which contribute thickness too; but that's enough wiggle-room already, I think. The cost to change the units for the cargo and container values really isn't that much. Is it more important than other changes that need to be made? Maybe not. But would it make the system better, on the whole? Sure thing. That's what suggestions are for.