**Spaceships & Vehicles**

Reality intersecting cargo ships , Ouch--help with math/reality in **Spaceships & Vehicles**

Ok, I did some research. Here are some numbers for you to chew on:

1 TEU = twenty foot equivalent unit = 1 "standard 20 ft cargo container"

Biggest ocean-going container ship = 15,000 TEU capacity

1 TEU = 39 cubic meters

1 Cargo Hold = 100 cubic meters

1 Cargo Hold = ~3 (being a little generous) TEU = 3 hull points = 1 hp/TEU

Biggest Warships freighter = Super-freighter with 3600 hp total.

At best, 2/3 can be cargo space = 2400 hp = 2400 TEU capacity

Ummm...anyone see a problem here? A SUPER-FREIGHTER has not quite a THIRD of the container capacity of a modern ocean-going container ship...granted a really big one.

Someone tell me where I went wrong and convince me that this isn't completely ridiculous.

1 TEU = twenty foot equivalent unit = 1 "standard 20 ft cargo container"

Biggest ocean-going container ship = 15,000 TEU capacity

1 TEU = 39 cubic meters

1 Cargo Hold = 100 cubic meters

1 Cargo Hold = ~3 (being a little generous) TEU = 3 hull points = 1 hp/TEU

Biggest Warships freighter = Super-freighter with 3600 hp total.

At best, 2/3 can be cargo space = 2400 hp = 2400 TEU capacity

Ummm...anyone see a problem here? A SUPER-FREIGHTER has not quite a THIRD of the container capacity of a modern ocean-going container ship...granted a really big one.

Someone tell me where I went wrong and convince me that this isn't completely ridiculous.

For starters, the SPACE ship has nothing but internal cargo space, rather than tons of cargo piled on top.

Also, sea ships are not known for FTL drives.

Also, sea ships are not known for FTL drives.

No sea craft has the engine power to lift its cargo into orbit. ALL starships are able to do that according to Warships. (all PL7+ engines can work in the atmosphere and a PL6 ship with Planetary thrusters can do the same)

I'll do a little math to see how frikkin high energy is required to lift even a medium-sized seagoing cargo vessel. And we are not talking of just pushing his mass along as seagoing ships do on sea or spaceships do in deep space. There is a planet that*strongly* wants to keep the cargo on the ground.

let's take a 20.000 ton ship for an example. Hansa Stravanger seized by somali pirates was a 20.000 container ship.

To accelerate it by 1 m/s^2 in deep space you need to apply 20.000 N.

If you are taking off the planet gravity pushes you down with an acceleration of (roughly) 10 m/s^2, so you need to apply 220.000 N to accelerate the ship by 1 m/s^2 !

If we are talking of energy usage:

Kinetic energy to reach 1 m/s in space is 10 Mj

Kinetic energy to reach 11 m/s in a gravity well that will eat 10 m/s each second (so the "visible" speed would be 1 m/s) 1,21 Gj

in both cases there is an increase of one order of magnitude in Earth's gravity well.

(assuming that my use of physics is correct )

Still, this opens some holes in the wall.... a ship created to travel only in space does not need all the bracing required to a ship that must withstand landings and take-offs.

Unless we say that a ship that has a gravitic engine will crumble under its own weight if the gravitic engine (that counters the gravity's effects) is depowered while it is on the ground.

I'll do a little math to see how frikkin high energy is required to lift even a medium-sized seagoing cargo vessel. And we are not talking of just pushing his mass along as seagoing ships do on sea or spaceships do in deep space. There is a planet that

let's take a 20.000 ton ship for an example. Hansa Stravanger seized by somali pirates was a 20.000 container ship.

To accelerate it by 1 m/s^2 in deep space you need to apply 20.000 N.

If you are taking off the planet gravity pushes you down with an acceleration of (roughly) 10 m/s^2, so you need to apply 220.000 N to accelerate the ship by 1 m/s^2 !

If we are talking of energy usage:

Kinetic energy to reach 1 m/s in space is 10 Mj

Kinetic energy to reach 11 m/s in a gravity well that will eat 10 m/s each second (so the "visible" speed would be 1 m/s) 1,21 Gj

in both cases there is an increase of one order of magnitude in Earth's gravity well.

(assuming that my use of physics is correct )

Still, this opens some holes in the wall.... a ship created to travel only in space does not need all the bracing required to a ship that must withstand landings and take-offs.

Unless we say that a ship that has a gravitic engine will crumble under its own weight if the gravitic engine (that counters the gravity's effects) is depowered while it is on the ground.

Author (Guardian @ Nov 17 2009, 18:21) |

For starters, the SPACE ship has nothing but internal cargo space, rather than tons of cargo piled on top. |

I think this is a key point, though not the whole story. Container vessels stack cargo on deck to an amazing height. I can easily believe they carry twice or more as large a volume of containers as would fit inside their actual hull.

There's no reason, on the face of it, a starship couldn't do something similar. Maybe we need to describe a Cargo Net or similar system, which has no armour or Durability or any other sort of structural integrity, just cargo capacity. Naturally, engine and FTL performance, or any sort of defensive field intended to cover the containers, would have to account for the hull size of the extra cargo, in the same way as for docking clamps.

Author (uncle_jimbo @ Nov 17 2009, 21:57) |

There's no reason, on the face of it, a starship couldn't do something similar. Maybe we need to describe a Cargo Net or similar system, which has no armour or Durability or any other sort of structural integrity, just cargo capacity. Naturally, engine and FTL performance, or any sort of defensive field intended to cover the containers, would have to account for the hull size of the extra cargo, in the same way as for docking clamps. |

Was just flicking back through these rules in Warships last night, though in regards to a jump-ship that ferries smaller craft. Came across that mention of ships only being able to dock up to 10% of their own hull points externally. That's obviously one thing you'd have to disregard entirely. And of course, as you mentioned, ensure it has an FTL drive capable of covering the maximum possible docked cargo containers.

edit: An Ultra-Large Crude Carrier, the largest of supertankers, can be just over 440,000 deadweight metric tonnes. Using a conversion factor for the density of crude oil, I make that about 500,000 cubic metres, or 15,000 Hull Points of cargo holds.

The*Warships* super-freighter is only the "largest ship built for routine commercial purposes". We know it's possible to build bigger ships. It's much smaller, for example, than the largest PL 7 warship, as opposed to today's super-tankers, which are larger than aircraft carriers (TI-class 379m vs. *Nimitz* class 333m). It's possible that the economy of PL 7 has no routine commercial purposes as grotesque as our oil usage.

This post has been edited by**uncle_jimbo** on Nov 17 2009, 12:50

The

This post has been edited by

The Alternity creators unfortunately fail completely when calculating things such as this. I had the same problem with the number of personel on The Lighthouse. A modern Aircraft carrirer can carry 7,000 personnel in addition to all their stores, equipment, and aircraft. They seriously shoot low on pretty much everything.

Actually, if we put aside the cargo volume and tonnage, the *Warships* super-freighter to fleet carrier comparison looks pretty much in line with today's equivalents in relative sizes (not in absolute terms). A fortress ship is just that much bigger than anything today.

Author (Velocity_Boost @ Nov 17 2009, 04:35) |

Was just flicking back through these rules in Warships last night, though in regards to a jump-ship that ferries smaller craft. Came across that mention of ships only being able to dock up to 10% of their own hull points externally. That's obviously one thing you'd have to disregard entirely. And of course, as you mentioned, ensure it has an FTL drive capable of covering the maximum possible docked cargo containers. |

That 10% limit is how much the ship can haul without degrading performance. it also goes on to state that a ship hauling half its size in docked craft must take into account the added hull points for engines, jammers and what not. 3 engines, 5% each for 15% on the Acc chart with undocked craft, adds 50% its hull... engine rating decreases as it needs to push added mass. there is no reason a freighter couldnt have... hmm... 3600 hp... 20%... 720 points of docking clamps, latch onto a hull that was nothing but cargo holds. 3600 pts of cargo holds, + internal, doubling the ships size, and cutting say.. 10% engines to 5%. you would have to over size any FTL to account for the added HP as well, but yeah... could do it.. hmm..

Guardian's initial response sums it up neatly.

A sea-going ship and a PL7 star-freighter are completely different vehicles. One floats on water like a giant steel ducky, and tootles about the sea at the speed of an arthritic moped. The other carries the energy potential of several nuclear holocausts for its motive power, and travels hundreds of times faster than a laser beam.

It's not very surprising that one can do more for less in terms of storage, when one does less with that storage.

If you find it really annoying, though, just put together an even bigger civilian hull.

A sea-going ship and a PL7 star-freighter are completely different vehicles. One floats on water like a giant steel ducky, and tootles about the sea at the speed of an arthritic moped. The other carries the energy potential of several nuclear holocausts for its motive power, and travels hundreds of times faster than a laser beam.

It's not very surprising that one can do more for less in terms of storage, when one does less with that storage.

If you find it really annoying, though, just put together an even bigger civilian hull.