Canonical Ships and their Shipyard

[veltyen]

Monster freighters would suck up large portions of an entire world's monthly trade with a partner, or more. There are not many trade pairs that could make it worth filling a 1MTd ship and keep it busy.

Probably not trade pairs.

Think a Megaton J5 vessel plying a path 10 parsecs apart (with a refueling stop) and then cargo radiating out from there along J1/J2 mains. At a Megaton that would only leave about 400,000 dTon of cargo to disperse on a 10+ week round trip. Still a lot of cargo, but also a vessel that would be useful for carting armies about.

On earth large container vessels carry 15,000 TEU [1]. But we have thousands of them for one measely little planet, and this isn't counting the bulk carriers and liquid carriers.

[1] TEU - 20 foot cargo container, about 3 dTon.

 

[rancke]

Monster freighters would suck up large portions of an entire world's monthly trade with a partner, or more. There are not many trade pairs that could make it worth filling a 1MTd ship and keep it busy.

What trade volumes are you basing that on? FT?


Hans

 

[Blue Ghost]

Monster freighters would suck up large portions of an entire world's monthly trade with a partner, or more. There are not many trade pairs that could make it worth filling a 1MTd ship and keep it busy.

Not sure I agree with that. Largely because we're talking about goods being shipped among world populations, and not just cities, which already see huge amounts of commercial traffic. But that's just my educated guess.

To get back on topic, here's a link; http://www.worsleyschool.net/science/files/supertanker/page.html

 

[aramis]

What trade volumes are you basing that on? FT?


Hans

It's the only source that generates reliable numbers... even if I feel it generates way to high a percentage of off-world trade.

The largest trade pairs and flows, maybe.

In rep to Veltyn: J5 cargo isn't how it's gonna work; the cost per ton-parsec is, except for time limited, too high past J2 with CT, MT, T20, and MGT.

J5 uses 80% for bridge, power, jump, and fuel.
IIRC, the best rate is J2 (31%) or J3 (42%), but I'm not doing the math tonight.
Not counting crew spaces. Half a million tons is, for a given trade pair, a considerable large lump. And its about what a 1MTd J3 with minimal crew should have. Not to mention the issues with loading that much on a single vessel.

 

[rancke]

IIRC, the best rate is J2 (31%) or J3 (42%), but I'm not doing the math tonight.

According to my calculations, J2 and J3 is almost the same cost (astrography permitting). J2 is slightly cheaper if you waste several percent of payload on carrying tons of power plant fuel, J3 is slightly cheaper if you don't.


Hans

 

[veltyen]

In rep to Veltyn: J5 cargo isn't how it's gonna work; the cost per ton-parsec is, except for time limited, too high past J2 with CT, MT, T20, and MGT.

J5 uses 80% for bridge, power, jump, and fuel.
IIRC, the best rate is J2 (31%) or J3 (42%), but I'm not doing the math tonight.
Not counting crew spaces. Half a million tons is, for a given trade pair, a considerable large lump. And its about what a 1MTd J3 with minimal crew should have. Not to mention the issues with loading that much on a single vessel.

At J5 I get about 260,000 dTon cargo space at TL14, and over 300,000 dTon of cargo space at TL15 as cargo space (under T20). Obviously a ship of this type would have very specific purposes - well outside the expectations of the normal cargo tables.

Think the Berlin airlift.

 

[aramis]

At J5 I get about 260,000 dTon cargo space at TL14, and over 300,000 dTon of cargo space at TL15 as cargo space (under T20). Obviously a ship of this type would have very specific purposes - well outside the expectations of the normal cargo tables.

Think the Berlin airlift.

Think financial fiasco. The costs of J5 are over double that of J2/J3 per ton-parsec, IIRC. Such folly is also far better served by smaller ships for many reasons.

1) Defensibility: it is actually easier to put many small ships through than one large one; a single lucky nuke can stop a large ship, while it takes at least 20 to kill 20 smaller targets.
2) lading: it is far easier to load/unload many smaller ships than a few large ones, as you have fewer choke-points.
3) Flexibility. One large ship can only go one place. Many smaller ships can disperse
4) construction times: it is generally better to build many small ships simultaneously than one large one, since the larger takes longer.
5) Construction costs: the cost of many smaller ships built at once is reduced.

And still 300,000Td is a 42,000,000m³... 46,350. 40' shipping containers. That's 92,700 TEUs. 7,000 TEU is BIG. the largest terrestrial design yet, and it's not built, is 22,000 TEU; just short of 72KTd. Total of the 10 biggest classes in service on earth at the moment is 705,963 TEU... smaller cargo carriers probably double that.

A single ship carrying about 5% of earths total wet-naval current container shipping capacity. And that's JUST 300KTd.

A J1 could conceivably carry 5% of Earth's total current shipping capacity. The load/unload nightmare... the 10KTEU ships already take 1-3 days of constant effort to unload. (Depends on the cranes and their operators.)


(numbers drawn from http://en.wikipedia.org/wiki/Container_ship and http://www.unc.edu/~rowlett/units/index.html )

 

[Blue Ghost]

It's the only source that generates reliable numbers... even if I feel it generates way to high a percentage of off-world trade.

The largest trade pairs and flows, maybe.

In rep to Veltyn: J5 cargo isn't how it's gonna work; the cost per ton-parsec is, except for time limited, too high past J2 with CT, MT, T20, and MGT.

J5 uses 80% for bridge, power, jump, and fuel.
IIRC, the best rate is J2 (31%) or J3 (42%), but I'm not doing the math tonight.
Not counting crew spaces. Half a million tons is, for a given trade pair, a considerable large lump. And its about what a 1MTd J3 with minimal crew should have. Not to mention the issues with loading that much on a single vessel.

Something else to consider is that some of those hulls may be strictly interplanetary affairs. Something like a 1g vacuum world that needs the ammonia from a local jovian body for fuel, might have one of these massive hulks lying about to "mine" the gas, and transport it back to world-X.

Similarly, such a craft might haul liquid nitrogen, methane, or any number of other chemicals and/or raw materials from one world to the next without leaving the system.

Just a thought.