Shipyard workers

[PFVA63]

TY.

Yes that was what I meant.

And, AFAIK, the largest aircraft carrier in the world is the USS Ronald Reagan, about 90000 tons displacement (assuming 50% of its volume under water, it would be about 180000 Kl, so its travelelr equivalent would be about 13000 dton.

So viewed, the less than 7000 people Hans calculated to build a 120000 dton (nearly 10 times the US Ronald Reagan) doesn't seem so impressive...

Hi,

As a side note, there is probably a fair bit more than 1/2 of a nuclear aircraft carrier's internal volume above the waterline. I had some data once for aircraft carriers, but am having touble locating it. However, for modern surface warships like frigates, destoyers and cruisers a rough rule of thumb is "divide the ship's listed hydrostatic displacement in metric tons by 4 to get a rough estimate of its internal volume in Traveller dtons".

Doing the math, this works out to a 4000mt frigate having roughly 1000dtons of internal volume (or 14000 cubic meters). Since Salt Water weighs roughly 1.025t/cubic meter that would mean that a 4000mt ship would have about 4100 cubic meters under the waterline and 9900 cubic meters above (14000-4100).

In pure volume terms that would mean that the volume of the hull above the wateline would be about 2.4 times what's below the waterline (in constant terms of cubic meters or cubic feet or whatever), or that only about 29% of the ship's internal volume is below the wateline.

I actually wouldn't be surprised if the amount of volume above the wateline for an aircraft carrier might even be a bit higher since they enclose alot of internal hangar volume and such.

Regards

PF

 

[atpollard]

I don't. I count the people who work at the plant where the parts are assembled.

I tried a bit of googling before posting my question, and I did find a descriptipn of a shipyard that had "over a thousand" or perhaps 1200 workers while it was working on three of these ships (the class mentioned at the top of the webpage) at the same time. But I can't figure out what Traveller tonnage the ships are.


Hans

I get about 7900 dT per ship for the bounding box. If the usable hull is around 80% of the bounding box, then about 6,300 dT per ship or about 19,000 dTons under construction for the 1000-1200 workers.

Don't forget to divide the 19,000 dT by the number of years to build it to get annual production. Since it looks like they take about 2 years per ship, the yard has a capacity of 9,500 dT per year ... or 8-9 dT per year per worker.

[all Quick and Dirty calculations.]

 

[PFVA63]

Hi,

If anyone is interested in comparing to modern ship design stuff, there were a number of studies and such done in the 1990's relating to shipyard productivity where they often measured things in terms of how much it cost or how many man-hours it would take to erect a certain amount of Compensated Gross Tons of Ships, where Compensated Gross Tons were a measure of big a ship was adjusted (or compensated) to also account for its relative complexity.

I can probably try and dig some of that info out if anyone is interested. As an example, one paper that I do have right now indicates that from a survey of US and foreign yards in the early 1990's indicated:

man-hours/CGT
- US Yards (average) = 184.8
- All Foreign Yards (average) = 88.0
- Specific Foreign Yards Visited = 40.0
- All Foreign Yards (range) = 17.0 to 180.0

cost/employee/year
- US Yards (average) = $52,500
- All Foreign Yards (average) = $63,455
- Specific Foreign Yards Visited = $48,690
- All Foreign Yards (range) = $11,290 to $104,960

cost/CGT
- US Yards (average) = $5,314
- All Foreign Yards (average) = $1,121
- Specific Foreign Yards Visited = $1,296
- All Foreign Yards (range) = $697 to $1,653

http://en.wikipedia.org/wiki/Compensated_gross_tonnage
http://www.coltoncompany.com/newsandcomment/news/CGT Factors.pdf

 

[atpollard]

From your earlier post 1 CGT = (more or less) 1 metric displacement tonne = (more or less) 1/4 Traveller dTon, correct?

 

[atpollard]

man-hours/CGT
- US Yards (average) = 184.8
- All Foreign Yards (range) = 17.0 to 180.0

cost/employee/year
- US Yards (average) = $52,500
- All Foreign Yards (range) = $11,290 to $104,960

Any idea which yard this is?
17 man-hours per CGT!
eleven times as efficient as US shipyards and 5 times as efficient as the world average.

 

[PFVA63]

Hi,

Its a little convoluted (I guess since it has to do with taxes and fees) but GROSS TONNAGE (GT) is a measure of the internal volume of a ship, defined as follows (see also http://en.wikipedia.org/wiki/Compensated_gross_tonnage ):

GT = K * V

where
V = the ship's total volume in cubic meters
K = a multiplier (between 0.22 to 0.32) defined as follows

K = 0.2 + 0.02 * log (V)

To get Compensated Gross Tonnage (CGT) you then have to adjust the numbers a bit more based on ship type as defined in this doc ( http://www.coltoncompany.com/newsandcomment/news/CGT Factors.pdf )

In general to get from GT to CGT you use the following formula:

CGT = A * GT^B

Where A & B vary by ship type, as defined in the doc listed above. For Reference here is a list of these coefficients for several ship types:

Ship type - A - B
Oil tankers (double hull) 48 0.57
Chemical tankers 84 0.55
Bulk carriers 29 0.61
Combined carriers 33 0.62
General cargo ships 27 0.64
Reefers 27 0.68
Full container 19 0.68
Ro ro vessels 32 0.63
Car carriers 15 0.70
LPG carriers 62 0.57
LNG carriers 32 0.68
Ferries 20 0.71
Passenger ships 49 0.67
Fishing vessels 24 0.71

I believe that other coefficients have been (or are being developed for warships) but I don't have any of them right now.

 

[rancke]

I get about 7900 dT per ship for the bounding box. If the usable hull is around 80% of the bounding box, then about 6,300 dT per ship or about 19,000 dTons under construction for the 1000-1200 workers.

Thank you, that's very useful.

Don't forget to divide the 19,000 dT by the number of years to build it to get annual production. Since it looks like they take about 2 years per ship, the yard has a capacity of 9,500 dT per year ... or 8-9 dT per year per worker.

Shipyard capacity is the tonnage you can work on simultaneously, so 19,000T would be the relevant figure for my purpose. So one worker per 16-19 T of capacity.

I'm not going to use a figure for TL7 surface ships directly on TL 9-15 starships, but I think it indicates a ballpark.


Hans

 

[Enoki]

I would add that you double or triple the tonnage in materials for the scrap, wastage, indirect materials (things used to build the ship but not part of it), etc., as the build weight.

As far as how much they can build that would depend on the equivalent of how many "slips" they have and what the size of those are. So, a yard that has one say, 10,000 ton slip (whatever the equivalent is here) can build one ship of 10,000 tons or less on it. Let's say they also have four 5,000 ton slips.

If they were building 2 500 ton merchants, 1 2,500 ton merchant, a 5,000 ton naval vessel and a 2,000 ton naval vessel, you might find all their available slips are taken up at the moment.

 

[atpollard]

For ships over 5000 dT, the 'slip' space available in a parking orbit is effectively infinite, is it not?

 

[HG_B]

For ships over 5000 dT, the 'slip' space available in a parking orbit is effectively infinite, is it not?

A mooring "slip" yes. A shipyard "dry-dock slip" no.

 

[BlackBat242]

Note that a USN aircraft carrier of the CVN type has a "keel to waterline" depth of ~40', and a "waterline to flight deck" height of ~75'.
Also note that there are large sponsons above the waterline which extend out considerably from the hull sides.

Therefore, the submerged enclosed volume is at most 30% of the total enclosed volume, and more likely ~25%.

Of course, part of that enclosed volume above the waterline is a very large empty volume known as "aircraft hangar", while the volume below the waterline contains the nuclear reactors, steam turbines, auxiliary diesel generators, tanks for aviation fuel, spare part/dry goods storerooms, and other high-density materials.

 

[rancke]

For ships over 5000 dT, the 'slip' space available in a parking orbit is effectively infinite, is it not?

A mooring "slip" yes. A shipyard "dry-dock slip" no.

IMO orbital 'slips' are simply made of scaffolding. Easily assembled in whatever sizes and configurations you need and easily dismantled and used for new 'slips' when the job is done.


Hans

 

[Enoki]

IMO orbital 'slips' are simply made of scaffolding. Easily assembled in whatever sizes and configurations you need and easily dismantled and used for new 'slips' when the job is done.


Hans

Wereas I would expect them to be more like giant hangers that are enclosed and the workers can operate without being in vac suits. That would make working both far easier and more comfortable meaning they are more efficent. It also allows for opening up the hull, running power cables, hoses, piping, and other external systems into the ship through open hatches without loss of internal pressure. This would also allow workers to enter the ship and exit without having to suit up, get out a suit, use air locks, etc., all of which would again slow the work down.
I Russia for example, shipyards located in more northern ports have covered and enclosed slips of this sort for construction due to the poor weather.

A simple scaffolding where workers are in vac suits or robots have to be used would be less desirable. So, while these would likely be available and used they would not be for many more complex and extensive jobs on ships. I could see these being for minor and exterior maintenance rather than heavy construction and repairs.

 

[rancke]

Wereas I would expect them to be more like giant hangers that are enclosed and the workers can operate without being in vac suits.

Wrap some custom-designed synthetic material around the scaffolding and you've got your enclosed space. Add modular 'work sheds' as required.


Hans

 

[DaveChase]

Inflatable bubble hanger.

Dave Chase

 

[CosmicGamer]

A simple scaffolding where workers are in vac suits or robots have to be used would be less desirable.

For a more automated system I guess all you need is an anchor point and all the robots can have zero G or magnetic maneuverability and zip about without scaffolding or any enclosure. The flesh supervisors can use the cameras and sensors of the constructobots for much of their work and if they have to get into a vacc suit at times, so be it.

Inflatable bubble hanger.

Whether it's humans or bots, I wonder what implications to tools used and mythology there would be based on the environment? I'm no science whiz but for starters changes in how things heat, cool, how chemicals like an epoxy work or paint dries.... Would it make having an enclosed hanger with an atmosphere more or less desirable? How about gravity? Certainly makes it easier to move stuff in Zero G but some things like just simply being able to set down your hammer and pick up a wrench now possibly require redesigned and more costly tools, changes in methodology, increase in time. Also there is the danger of loose things flying accidentally about as well as controlling any liquids that may be used during construction and the "waste" such as when cutting and grinding things.

Humans might be more careless and accident prone than bots and there are lots dangerous things meant to cut, pierce, melt and dissolve used during construction so I'd think any "bubble" would have to be very very durable or else everyone would still have to wear their vacc suit for safety reasons.

 

[Greylond]

Also, once you get the outer hull even partially closed in, pressurize it and work from the inside. I would think getting the primary superstructure and outer hull completed would be the first step anyway.

 

[BytePro]

In the RW, the bulk of labor for large scale construction projects consists of migrant and transient workers. The number of workers at any given time will vary - often quite drastically based on scope and current stages of constructions...

The original question doesn't have a single valid answer - especially with TL and government types considered.

However, the size of the shipyard could determine the size of permanent workforce - the management and skilled labor requisite for undertaking the scale of shipbuilding a shipyard is capable of producing. Dave's approach should suffice for the technical side of things... with the larger bulk of the direct and indirect labor labor force determined by other factors. (How many to build a section of hull is dependent on method of obtaining resources - asteroid vs strip mining - working the resources - smelting/casting/welding - and local work regulation and organizations such as unions, government work programs, migrant policies, etc.)

The construction capacity of a shipyard may be dependent on the size of the local and temporarily available (in-system or interstellar) workforce. The capability of a shipyard (ala drive TL manufacturing) would affect the requisite size of the shipyard.

 

[HG_B]

IMO orbital 'slips' are simply made of scaffolding. Easily assembled in whatever sizes and configurations you need and easily dismantled and used for new 'slips' when the job is done.


Hans

If you are talking about ones for construction, it wouldn't be anywhere near that easy. Moving huge, massive pieces of material around in zero-g is not simple. It requires much more than throwing up scaffolding. As you know weightless isn't mass-less. When you explore it from that angle, you soon see that it isn't going to be how you portray it.

 

[HG_B]

In the RW, the bulk of labor for large scale construction projects consists of migrant and transient workers.

This isn't the case for building high tech, large ships. Not at all.