Ship Construction

[Timerover51]

Waste disposal is handled by injection into the fusion power exhaust = instant plasma. No pollution. But I like the idea of capturing waste in a black water tank for sale to sealed environment ports of call who can make use of the organics.

You could dump it that way, but I tend not to be too wasteful, and if you heat it to extract all of the water, what you have left is reasonably good fertilizer. That should always have a market. If nothing else, the Star Port might want it for the plants in the port.

No colony can exist without dependable local air, water, and food. The former two are mined from asteroids and comets, if nothing else is around. It might get expensive on some weird, tiny colony, handled as a special case as part of game play. Any colony may make use of imported products for quality, variety, and luxury.

Any colony is always going to be using imported products. Depending on its size, it might be totally dependent on imported products for its equipment, and possibly food. One Traveller dTon is sufficient room for food for 5 people for one year.

 

[whartung]

You could dump it that way, but I tend not to be too wasteful, and if you heat it to extract all of the water, what you have left is reasonably good fertilizer. That should always have a market. If nothing else, the Star Port might want it for the plants in the port.

No thanks. The compost pile is outdoors for a reason. I don't think that the starports are hard up enough for compost that every ship in the fleet is going to making some to drop off each week.

 

[Timerover51]

I have started work on the ship construction rules, after going over the construction costs in both the Cepheus Engine SRD and the Little Black Books. In both cases, the construction cost per ton jumps from 20,000 Credits per ton for a 100 dTon ship through stages until in both cases at the 800 Ton ship the construction cost is 100,000 Credits per ton, the same as a custom-designed hull. You do get a 10% reduction in cost for the hull for a standard design, shown in a table in the LBBs, and covered in the standard vessels portion of the Cepheus SRD. The jump on cost for a civilian ship does not make a whole lot of sense. I suspect that it is a consequence of mixing civilian and military ship construction under the same format.

After going over some Real World ship costs, the cost of hull construction for a civilian ship is going to be 40,000 Credits per ton, the same cost as the 200, 300, and 400 dTon ships. For a military ship, the cost will be 100,000 Credits per ton, reflecting a much greater degree of internal sub-division in order to retain compartment pressure in the event of a hull breach. This will be manifested in thicker bulkheads and pressure-tight partitions, along with a higher quality of steel, HY-120, to resist damage. Civilian ships will be built using a vanadium alloy of around HY-55 to HY-60, more than adequate to resist pressure differentials between the inside atmosphere and the outside pressure, and also resistant to small arms and light artillery damage. Remember, a civilian ship used in trade MUST turn a profit. A military ship does not.

I will be doing a lot more number crunching to make sure that this will work.

 

[Timerover51]

The next issue is construction times. In the Cepheus Engine System Reference Document, ship construction times start at 36 weeks for a 100 ton ship and increase 8 weeks for every 100 ton increase in size. A 1400 ton hull will cost 140 weeks to build or over 32 months, while a 5,000 ton hull will take 428 weeks to build or just under 8 years and 3 months.

Now, the reason for highlighting the 1400 ton ship is that is just about the size of the World War 2 Liberty ship. The first Liberty ship took 244 days to complete, or a little under 35 weeks. With a lot of pre-fabrication, the average assembly time dropped to 42 days or 6 weeks. The 5,000 ton hull, or 25,000 Gross Register Tons, is just a bit smaller than the WW2 Essex-class of 27,000 displacement tons, many of which were completed in less that 2 years, or 104 weeks. As warships, the Essex-class were considerably more complex than an equivalent size of merchant ship.

Oddly enough, smaller ships take longer than larger ships, as not as many men can work on them at the same time. but a lot of the same amount of work has to be done. What I am looking at is probably a range band for ship completion based on the size and also the type of starport doing the building. I am going with Class "A" starports can build a starship from scratch, Class "B" starports can build ships by importing some components, and Class "C" starports can build the occasional small ship with the help of imported components, but it will take longer to complete.

 

[wellis]

Weren't Liberty ships buult extremely cheaply, to the point their QC could be pretty spotty as well sometimes?

 

[Condottiere]

I think the record was twenty four hours construction time.

They were like one shot jump drives.

 

[whartung]

With a lot of pre-fabrication, the average assembly time dropped to 42 days or 6 weeks.

You're not taking in to account then the time to prefabricate the modules.

The key point here is that the pre-fab modules were (I'm assuming) built on land, whereas the ship was built in a dry dock.

Dry dock capacity is farm more limited than land based manufacturing, allowing the construction of prefab modules to scale to the point where the ships were simply assembled quickly in the limited dry dock space, they could then be launched and have their outfitting finished while simply docked.

Arguably, while starship shipsyards in theory have a "capacity", it's not a space problem, especially orbital shipyards. It's more a resourcing, staging, and labor problem.

So, its important to consider the prefabrication costs and timelines in your construction estimates. Those don't come for free.

 

[PVernon]

They were not assembled in a dry-dock, but on a slipway on the beach. There is a photo (somewhere) that shows about 10 (more?) ship being assembled on a beach in California (?).

 

[Timerover51]

I think the record was twenty four hours construction time.

They were like one shot jump drives.

The record time was under 5 days, but that was a publicity stunt. As for them being built cheaply, they were the foundation of the World's shipping fleet following the war, and most lasted about 20 years. They were designed to be inexpensive to build, not built cheaply. If you want, you can still sail on two of them, the SS John W. Brown in Baltimore, Maryland and the SS Jeremiah O'Brien in San Francisco. According to Wikipedia, over 2400 survived the war. Quiet a few of them survived winter voyages across the North Atlantic and also trip to Murmansk, USSR in winter. One, the SS Stephen Hopkins, sank an attacking German surface raider, while being sunk itself. I will need to check on the numbers surviving the war in my hard cover copy of a history of the Liberty Ships.

There was some problems with welding, but that was not restricted to the Liberty ships. One U.S. heavy cruiser lost its bow due to defective welding.

They definitely were NOT like one-shot Jump Drives. They were still part of the Navy's Sealift fleet in the Vietnam war, and U.S. Army transportation manuals, which I did have to learn as a Quartermaster Officer, were still listing the various cargo loadings through 1967. I would suggest that you do some reading on the type.

 

[Timerover51]

They were not assembled in a dry-dock, but on a slipway on the beach. There is a photo (somewhere) that shows about 10 (more?) ship being assembled on a beach in California (?).

Very few ships in World War 2 were build in dry docks, as that tied up a restricted commodity that was needed for repairing damaged ships. Most warships and cargo ships were built on slipways as a slight angle to the water in order to launch them. In the Great Lakes, submarines were built side on to the water and launched sideways.

 

[whartung]

They were not assembled in a dry-dock, but on a slipway on the beach.

We have a lot of beach in Southern California.

But, that said, we have a lot more flat land for manufacturing. While slipways no doubt extend the capacity for ship building, it's still potentially a more limited resource than the manufacturing capacity capable of feeding it.

 

[Timerover51]

I think that what I will do with ship construction times is run a reverse bell-shaped curve, with the smaller ships and the largest ships taking the longer time to build, while the medium-size ships will take the shorter build times. As a rough guess, up to 500 tons will take 12 months to build or so, with a ship of about 1500 tons taking 9 months to build, with around 2500 tones back up to 12 months, and 5000 tons ships taking 24 months. Those would be civilian ships. Military ships will take at least 50 per cent longer. I am thinking of tossing in reductions for building at a Class A starport, and maybe some reduction for the standard type of Jump Drive ship.

I need to do some more thinking about the whole idea of standard, streamlined, and distributed, meaning totally non-streamlined and unable to land in an atmosphere. I do not think that there would be that many of that type in the sector, but you never know what some people might want to build.

Next up comes drives.

 

[kilemall]

I always considered distributed to be perfect candidates for future container ships. Fast detach/attach.


Star Citizen has a good conception for this sort of ship, the standardized Hull classes.


https://robertsspaceindustries.com/...661-A-Hull-For-Every-Job-The-MISC-Hull-Series


They solve the landing part by having the ship go at least standard transformer style. I don't think we would do that, just think of this in permanent cargo mode.


Another example would be the freighters from Silent Running (the scifi movie).


Ditch the domes and attach cargo canisters directly onto the girders.

 

[Timerover51]

I owe the forum an update on this. Much to my sorrow, I am not that much further along with this. I guess one of my New Year resolutions will be to get cracking on this and get something done.