What is the working life time of a space craft?

[Drakon]

There is a story about a person who claimed to have George Washington's axe, the very axe that Mr. Washington used as a boy to chop down a cherry tree. The axe looked brand new, because in the intervening 2 centuries it has replaced the head 6 times and the handle 7.

I am not sure an equivalent can be found rules. Bookkeeping would be complicated as one would have to keep track of individual components installation dates, instead of a the ship as a whole, but there should be a means of repairing a system to new or better than new condition.
QREBS?

Many of these component like wiring, piping, valves, motors, actuators, avionics, engines, etc. can be made modular and replaceable. Many of the standard Traveller ships designs have been out for many years, and aftermarket replacement and upgrades, even going to structural components like keel, frame and hull, could be a very lucrative business. Another factor is various 3D printing technologies making it easier for outposts to manufacture replacement parts from scrap or locally obtained materials. All these factors would combine to greatly extend the useful life of a space ship.

 

[Enoki]

I for one can see a ship having modifications over its lifetime, even lots of modifications. One of the consequences of that is such a ship also has a lot of now disused piping, wiring, and other stuff all over the place.
All you have to do to know that is have worked on ships (here on Earth...) or large commercial buildings. Even old homes will have this sort of thing inside them.
All that stuff adds to issues with the ship's integrity of bulkheads and compartments. It can constitute a fire hazard and is a problem when troubleshooting systems as it gets in the way.
Add in improper and poorly "engineered" modifications along the way and you get a ship that's full of issues and problems.

Many of these component like wiring, piping, valves, motors, actuators, avionics, engines, etc. can be made modular and replaceable. Many of the standard Traveller ships designs have been out for many years, and aftermarket replacement and upgrades, even going to structural components like keel, frame and hull, could be a very lucrative business. Another factor is various 3D printing technologies making it easier for outposts to manufacture replacement parts from scrap or locally obtained materials. All these factors would combine to greatly extend the useful life of a space ship.

An example here might be the ship sets down at some starport. The engineer says they need a new electric motor to run some vital piece of machinery. But, the only electric motor available isn't the exact, correct size (this is called "Frame size" in current terms) and uses a different voltage. But, they gotta have one. So, our enterprising engineer gets a transformer to get the right voltage to the new motor, buys the closest fit size one he can, then modifies the mounting(s) to make it work. Captain's happy, his ship runs. The engineer's happy the Captain's happy.
Down the road, the next owner of the ship is all WTF were they thinking?

 

[flykiller]

I can't see their needing something that's powered because that means the ship has to remain running or have a off ship power connection at all times to maintain the fuel tank integrity.

yeah ... yeah, that's true. yet another great idea shot down by common sense. bummer.

 

[aramis]

An example here might be the ship sets down at some starport. The engineer says they need a new electric motor to run some vital piece of machinery. But, the only electric motor available isn't the exact, correct size (this is called "Frame size" in current terms) and uses a different voltage. But, they gotta have one. So, our enterprising engineer gets a transformer to get the right voltage to the new motor, buys the closest fit size one he can, then modifies the mounting(s) to make it work. Captain's happy, his ship runs. The engineer's happy the Captain's happy.
Down the road, the next owner of the ship is all WTF were they thinking?

You can see examples of this kind of work in various episodes of "Deadliest Catch" - especially on the Cornelia Marie and the Time Bandit. (What they don't show you is that they fixed it "to spec" during the off season most of the time.) That's what Annual Maintenance is for. And bodges are great ways to justify some extra cash for the Annual.

Also, the Annual Maintenance is also when the worthiness cert gets checked off... Put her in the yard, have her brought to spec, all the fluids changed out, all the engines taken down and checked... )

And for comparison... the check schedule for a 747 Classic and a 747/400-D (from Boeing's Website)

Check Type	Takes	747 Classic	747/400-D
Daily Check	15-30 min
A check	4-12 hours	300 Hours	600 hours
B check	1/2 to 3 days
C check	5-15 days	3000 Hours or 15 months	600 hours or 18 months
D check	20-30 days	25,000 Hours or 5 years	6 years

[tc=2]Before each flight day[/tc] [tc=2]Not on schedule[/tc]

Note: B checks are usually followups from a trouble ticket or a failure on daily checks.

 

[kilemall]

yeah ... yeah, that's true. yet another great idea shot down by common sense. bummer.

Fret not, there is always metallic hydrogen.

https://www.sciencenews.org/article/pressure-make-metallic-hydrogen

Several options that may pan out there.

 

[Enoki]

I know in real life, all-too-well, how maintenance on complex systems is...

As but one example over decades, right after 9/11 I went to San Diego to help a USN frigate that was in Continental Marine's yard for repairs (right under the Coronado Bridge) get a .... load of electrical problems sorted out.
Without going into details, main lube oil for the engines wouldn't shift from normal to emergency and back, the stabilization system for smoothing out the ride didn't work, the flight deck systems were a disaster... etc.
Now, this is a USN ship (ie., the equivalent of something Imperial Navy). The crew was unable to troubleshoot and fix the systems, hence why they wanted somebody like me to show up and do it.
I also supervised the installation of several new pieces of galley equipment including running new cable and breakers. That was quite the Rube Goldberg installation there. The crew had no idea on ampacity or cable sizing.

Old = messed up. That's decades of experience talking. Nothing like finding a desk light... on and still working no less... under the raised deck plates of the CIC on an aircraft carrier to teach you about useless abandoned junk that shouldn't be there...

 

[kilemall]

I know in real life, all-too-well, how maintenance on complex systems is...

As but one example over decades, right after 9/11 I went to San Diego to help a USN frigate that was in Continental Marine's yard for repairs (right under the Coronado Bridge) get a .... load of electrical problems sorted out.
Without going into details, main lube oil for the engines wouldn't shift from normal to emergency and back, the stabilization system for smoothing out the ride didn't work, the flight deck systems were a disaster... etc.
Now, this is a USN ship (ie., the equivalent of something Imperial Navy). The crew was unable to troubleshoot and fix the systems, hence why they wanted somebody like me to show up and do it.
I also supervised the installation of several new pieces of galley equipment including running new cable and breakers. That was quite the Rube Goldberg installation there. The crew had no idea on ampacity or cable sizing.

Old = messed up. That's decades of experience talking. Nothing like finding a desk light... on and still working no less... under the raised deck plates of the CIC on an aircraft carrier to teach you about useless abandoned junk that shouldn't be there...

Computer rooms are the same way, decades of 'we don't have time to pull this or the stomach for any unexpected downtime generation' will leave horrid messes that are much worse to untangle later on.

Not to mention troubleshooting datacomm in a snarlball.

 

[Selandia]

imtu high-tech construction is taken up almost exclusively by the navy, leaving low-tech building to the civvies, so it's fairly stable in that regard. the big hurdle is affording a ship at all, not the transition from tech 11 to tech 12.

You are right in thinking that setting up a liner service to cash in on a trade route has as main barrier to entry the high capital cost of ships (very high), setting up business and cash flow reserve in a context of low return on investment during the market war.

If I want to stand a better chance (cutting my cost so that I can cut freight rate below cost of my competitor but above mine) I use the economic benefit (engine cost or efficiency, fuel) that come with +1 or +2 TL

If you were linking Regina and Rethe with 3xJ2 jumps and a competitor introduce ships one TL above to get it done in 2xJ3, ...

Evolution of basic trade include the appearance of a high port for a planet. Landers do not have the same edge once cargo transfert from orbit is optimised at high port.

The developpement of a new mining facility that require import of machinery too large for current liners to cary without on-site reassembly open the door to a newcommer with a ship capable to take them on whole. That will provide the early impetus required by a newcomer. The old time firms may simply undermine any newcomer's attempt by having such a ship built for their line and one of the current serving one put up for sale or reassigned.

Substance X requiring special cargo handling gear could be imported from world A more cheaply than it could be produced on B. However nobody cared on B for X... until a facility requiring X is opened on B. Retrofit or new ship is required.

and so on....

Have fun

Selandia

 

[flykiller]

The crew had no idea on ampacity or cable sizing.

went through ema school and nuclear power school and prototype, but didn't really understand it all until a tech was on board and took half an hour to point out a couple of things. so many lights dawned.

on one system I found 1) the fuse had blown 2) the motor winding had burnt through 3) the relay coil connection had corroded open 4) the power connector box tie had corroded open and 5) a wire had burnt open - just the wire, not the insulation, there was no external sign whatsoever that the wire had opened. took a long time to chase down all that.

in another a bus bar connector riser had corroded open. cinched down tight, a half inch of threads metal to metal, inside a sealed bus bar box, no visible problem whatsoever, but no electrical connection. unscrewed it, screwed it back in, worked.

lots of people get frustrated, tell the chief they have no idea what the problem is, go watch tv in the lounge ....