CT Only: Spinward Flex Courier

[coliver988]

There is a lot to digest here! One thing I noticed though was the implication fuel processors need to use wilderness refueling. I don't believe there is a reason you could not just slurp up the unrefined fuel at the port and process it there. More Cr than wilderness, but you are at the port.

And sorry if this was mentioned in thread somewhere - as I said, there is a LOT of text and I skimmed a bit as I am unable to keep up!

And pretty sure there was a thread a while ago (perhaps this very thread!) about using the fuel processors while at port to process fuel for the port while you are there. Get paid for that week instead of paying for that week.

 

[bookwyrm]

this side trip into how can a Star Port provide fuel to space/star ships when the main world it services has hydrographic 0 is pretty cool. I got to thinking (this past Friday) about what to do if there is no gas giant in the system.

Frenzie - Vilis Subsector - Spinward Marches 1116
A200436-A N pbg110 X-Boat Station
8 parsecs from D'Ganzio

Frenzie is one of 147 systems in the Third Imperium that are hydrographic 0, Class A-D Star Ports, and no gas giant. some of these systems have Naval and/or Scout Bases, X-Boat Stations, and Depots in them.

my first thought was for these systems to transport fuel from the nearest system with a gas giant, then included, or worlds with water.
my second thought a little later was 'I wonder if there are any other planets in the system that might have water'.

it turns out that, some of these systems are going to pay dearly to bring in fuel from other systems. on the other hand, all 147 of these systems have 1+ other planets. I would think that the systems with Naval & Scout Bases, X-Boat Stations, and Depots, there is probably a planet in the systems with water. and a good chance for most, if not all, of the other systems.

for those who want to know, my search at Traveller Map used this:
uwp:[A-D]??0???-? pbg:??0 alleg:Im*

for extra credit, I found 40 systems where the main world has atmosphere B-C, Class A-D Star Ports, Hydrographic ?, and no gas giant. you probably wouldn't want to pump liquids from these worlds into your ship. and they all have 1+ other planets also.

 

[whartung]

The other alternative is mostly ice base asteroids if there's a handy asteroid belt.

 

[Silverhawk]

this side trip into how can a Star Port provide fuel to space/star ships when the main world it services has hydrographic 0 is pretty cool. I got to thinking (this past Friday) about what to do if there is no gas giant in the system.

Frenzie - Vilis Subsector - Spinward Marches 1116
A200436-A N pbg110 X-Boat Station
8 parsecs from D'Ganzio

Frenzie is one of 147 systems in the Third Imperium that are hydrographic 0, Class A-D Star Ports, and no gas giant. some of these systems have Naval and/or Scout Bases, X-Boat Stations, and Depots in them.

my first thought was for these systems to transport fuel from the nearest system with a gas giant, then included, or worlds with water.
my second thought a little later was 'I wonder if there are any other planets in the system that might have water'.

it turns out that, some of these systems are going to pay dearly to bring in fuel from other systems. on the other hand, all 147 of these systems have 1+ other planets. I would think that the systems with Naval & Scout Bases, X-Boat Stations, and Depots, there is probably a planet in the systems with water. and a good chance for most, if not all, of the other systems.

for those who want to know, my search at Traveller Map used this:
uwp:[A-D]??0???-? pbg:??0 alleg:Im*

for extra credit, I found 40 systems where the main world has atmosphere B-C, Class A-D Star Ports, Hydrographic ?, and no gas giant. you probably wouldn't want to pump liquids from these worlds into your ship. and they all have 1+ other planets also.

This situation might be partly why the price of fuel is set. One would think that market forces would have it cheaper in heavily trafficked systems and expensive in places like Frenzie. However, if the price is the same at both that would imply a pricing set up more like sending a first class letter today. Flat price regardless of distance.

 

[Spinward Flow]

There is a lot to digest here!
And sorry if this was mentioned in thread somewhere - as I said, there is a LOT of text and I skimmed a bit as I am unable to keep up!

You flatter me.
I have been trying to "pace myself" with updates to this thread simply in order to allow others time to read/skim through everything at their leisure, because ... well ... there's a LOT of text and ideas to assimilate lying around here (for some odd reason...).

One thing I noticed though was the implication fuel processors need to use wilderness refueling. I don't believe there is a reason you could not just slurp up the unrefined fuel at the port and process it there. More Cr than wilderness, but you are at the port.

And pretty sure there was a thread a while ago (perhaps this very thread!) about using the fuel processors while at port to process fuel for the port while you are there. Get paid for that week instead of paying for that week.

Technically true from a rules standpoint, but quickly runs into common sense problems relatively rapidly.
For one thing, type A and B starports are the only ones with refined fuel available, while type C and D starports (and most spaceports that offer fuel) only have unrefined fuel. Yes, while the ship is berthed in a starport it can act as a stationary fuel refinery (I mean, the capability to do so is there if you have a fuel purification plant onboard) ... but type C and D starports don't sell refined fuel (by definition) and type A and B starports will have their own refinery facilities and won't need to pay your starship for the service while berthed at the starport (barring emergencies, of course).

So in the places where the starport can sell the refined fuel, they don't need your ship to refine it ... and in the places where they don't sell refined fuel, they don't sell refined fuel ... so there's a little bit of a catch-22 going on there. Besides, under most circumstances, the starport will often times have "easy access" to starship fuel feedstock sources (liquid water oceans being one of the more common, but by no means the only) and thus have no "need" for your ship's fuel purification plant to donate refining time to the starport.
Under MOST circumstances that is true ... if you take a close look around, you will be able to find exceptions to this generic rule.

D'Ganzio / Lanth / Spinward Marches is one of those exceptions, owing to the distribution of resources (in this case, starship fuel) within the system. However, the same is NOT true at Lanth/Lanth (with its hydrographic code: 9) and so they would have no "need" allow for arbitrage of unrefined fuel sold by the starport to be purchased back as refined fuel after processing by a starship's fuel purification plant while berthed there. The starport may buy a few stray tons of fuel here and there (as a courtesy) to starship captains wanting to purge their fuel tanks to replace unrefined fuel with refined fuel, but they aren't going to just hook up a fuel pipeline to a starship and PAY THEM for the privilege of refining fuel for the starport (the starport has its own facilities for that).

this side trip into how can a Star Port provide fuel to space/star ships when the main world it services has hydrographic 0 is pretty cool.

Indeed. It's one of those things where until you start to think about it you usually just can't be bothered to worry about it.
There's a starport there, meaning they have all the fuel to sell you that you would ever need.
How do they get it?
Um ... space magic?

Also, just because a world has a hydrographic code: 0 doesn't mean that there is NO water present on the world at all ... it just means that there isn't enough of it (easily accessible) on the surface. It could be locked up in ice caps (which has been a world description item since CT), which tends so show up with hydrographic code: 1+ and atmosphere code: 0-1. So for ice capped worlds, the easiest supply method would be what amounts to ice mining on the edges of the polar caps. For desert worlds (hydrographic code: 0) it could mean subsurface mining to reach water locked up either in rocks or underground reservoirs (think oil drilling/natural gas fracking, except you're doing it to extract water). However, depending on the social/cultural significance of water on a desert world (looking at you, Dune!) it could easily be treated as too precious a resource (needed to sustain life!) to "waste" on diverting it into space as fuel for spacecraft and starships. In that case, even if subsurface water deposits are accessible by mining/drilling, the local culture may insist that such water resources are reserved for people/food and not to be used for the space economy ... forcing acquisition of ship fuel resources offworld.

The most convenient location for such offworld fuel reserves is going to be a gas giant (or few) ... while the next best is going to be an asteroid/planetoid belt beyond the snow line (outer system orbits beyond the habitable zone) that retains a lot of water and ices, creating a Belter space economy for ship fuels. And of course, in the most extreme of circumstances, fuel would need to shipped in from other star systems nearby ... although such an operation involving jumps to deliver fuel to a space economy is going to favor internal tankage starship designs over external tankage, simply due to the limitations of carrying capacity through jump. It's a lot easier to maneuver a large quantity of fuel (1000+ tons) in an external fuel tank multiple times a starship's tonnage (as I've already demonstrated) inside of a system than it is to import fuel using an internal fuel tank from a parsec (or few) away via jump drive. It CAN be done, of course, but there's a lot more logistical friction the further afield you need to go in order to secure a reliable and regular supply of fuel for a space economy (particularly if that space economy is expanding!).

The other alternative is mostly ice base asteroids if there's a handy asteroid belt.

Exactly, although for various reasons, the logistics of such things can get complicated in a hurry, depending on local "terrain" factors.
An exploration of exactly what those can entail is left as an extra credit exercise for the overly enthusiastic thread reader.

it turns out that, some of these systems are going to pay dearly to bring in fuel from other systems.

Cue the PROFIT MOTIVE for wanting to exploit such circumstances ...

9th Rule of Acquisition
Opportunity plus Instinct equals Profit!

10th Rule of Acquisition
Greed is eternal!

74th Rule of Acquisition
Knowledge equals profit.

 

[Spinward Flow]

There is a lot to digest here!
And sorry if this was mentioned in thread somewhere - as I said, there is a LOT of text and I skimmed a bit as I am unable to keep up!

Just circling back to this point ... because ... well ... ownership of horn involved in the making of the sounds.

When I said (months ago, now) that this whacktastic 194-ton starship design (definitely one of the oddest tonnages to land on that I have ever seen! ) had a lot of potential in it to open up new markets and new opportunities in ways and places that Free Traders and Far Traders would find difficult to compete with ... I kinda sorta had an inkling that building a generalized "workhorse" of a starship design that had "room to grow" its capacity beyond the confines of its hull interior would yield a highly efficient, all around "decent" competitive option to owning a Free Trader or a Far Trader.

The simple fact of the matter is that Free Traders and Far Traders are starships optimized for two things ... passengers and cargo ... and they basically need both (and plenty of them!) in order to operate at a profit (or close to a profit under a bank loan), with the remainder depending on "luck" in the form of speculative cargo arbitrage. Both of these starships "got their jobs done" but they really don't have any potential room for expansion of their capabilities. Their "growth factor" is largely played out in both designs, because they're "all internal" starships with no towing capacity (per RAW) ... so WYSIWYG (or at least, hope to get). Free Traders and Far Traders have a pretty firm "ceiling" on their capabilities ... which usually isn't a problem because they're relatively CHEAP to buy (being standard designs) if perhaps not quite so cheap to own and operate as they might at first appear (as demonstrated in this thread).

By contrast, the 194-ton Courier starship designs, through their innate external cargo capacity (maneuver and jump) mean that there is a huge variety of possible ways, means and configurations available to leverage that external capacity to tremendous advantage ... allowing these starships to undertake roles, missions and contracts that far exceed their hull size code. When you have a starship design with this much external capacity available, it's almost a crime to not start looking around to find ways to leverage it to your own advantage ... and the only limitation on that potential lies in the creativity of the owners/captains/crews.

I mean, I've mentioned before that a simple 20 ton hull (configuration: 4) could have 5 staterooms (20 tons) or 4 staterooms and 4 low berths (also 20 tons) or 40 low berths (still 20 tons) would be all you need to turn these 194-ton starships into passenger liners.
For a route that requires 2J1 at any point, a Spinward Courier (5G or 6G) could simply transport 4x 20 ton modules externally plus 1x 20 ton module internally ... and be able to devote 100 tons towards passenger services (staterooms, low berths, stewards and medic) on interstellar routes (jump-1 mains preferred, of course).
Alternatively, a Spinward Courier could offer a staggering 1200/20 = 60 passenger modules (5G) or 1180/20 = 74 passenger modules (6G) for Interplanetary Cruises at 1G within a specific star system, purely as a high passenger luxury touring service stopping at various ports of call around the star system.

• 60 passenger modules = up to 300 staterooms (5G)
• 74 passenger modules = up to 370 staterooms (6G)

241-360 passengers requires 3 medics (1 medic per 120 passengers).
297/9 = 33 stewards + 264 high passengers
367/9 = 40 stewards + 320 high passengers + 20 low passengers

If limiting things to only 240 passengers (so only 2 medics needed) you wind up with 30 stewards for 240 high passengers and a demand for 51 passenger modules of 20 tons each (with 12 tons total left over for "whatever you want" in one of the container modules) with room to add more modules (for Fine Dining Workshops and Auditorium spaces to hold entertainments, such as zero-g games, and the like if you want to go all in on the opulence of the experience).

Sure, it would be like going on a cruise in a shipping container (kinda sorta, because you are, but that's also an authentic sea going cruise ship these days) ... but if you "daisy chain" them all of those containers together in the right configuration(s), they'll just feel like being in a high rise hotel (in SPAAAAAAAAACE!!!!) with 5 rooms to a floor, elevator access between passenger modules, and with a gentle spin on the starship the view outside the windows will slowly change so you can see different sights at different times out the windows.

And to top it all off, you've still got a Mail Vault in the starship for carrying X-Mail between worlds and moons on the tour to help defray expenses (mainly stewards and life support costs at that point). Even better yet, individual passenger modules can be loaded into the Spinward Courier's internal cargo bay 2 at a time (40 ton capacity) for transfers from orbit to surface and back to orbit (which represents a 25+ orbital shuttle runs for 50 modules, which will take a while to complete, but it is doable if there is no highport and a world/moon has an atmosphere) ... so ports of call can be almost anywhere within a system.

Can a Free Trader do that?
Not on your life.

Can a Far Trader do that?
Don't make me cackle.

Subsidized Merchant? Subsidized Liner?
Um ... no and no.

Why?
Lack of "spare" drive capacity means that all of those legacy starships lack the external towing capacity of the whacktastic 194-ton starship design that even has the capability of being a(n external) fuel tanker if the merchant line gets a contract for that kind of business ... again, something that no Free Trader, Far Trader, Subsidized Merchant or Subsidized Liner could attempt to do with their starships.

So the (external) "towing capacity" is the REAL secret weapon inside of the design of these starships ... a factor that I have yet to see anyone even approach attempting to exploit on these forums up until now. In fact, the closest competitor to these capabilities that I can find is (ironically) found in LBB S9, p22-23 ... the Jump Ship ... with its 1000 ton standard modules (cargo, passenger, low pod). To be fair, though, the Jump Ship is a TL=15 design and as such is going to be essentially "tethered" to high population TL=15 type A and B starports by their economics, of which there are few on the fringes of the Third Imperium (the Spinward Marches only had 4 systems that meet that criteria in 1105 ... Glisten, Rhylanor, Mora and Trin).

And it's at times like this ... thinking about my whacktastic 194-ton starship designs, what some of the nay-sayers have said about them and my attempts to explain what's going on behind the Naval Architect ... it's times like this that I'm reminded of what John Crichton once told Officer Aeryn Sun to win her over.

You can be more.

And seriously ... as (fellow) Travellers, what more could you ask for ... as a Player, or as a Referee?

You can be more.

 

[Spinward Flow]

So here's a little thought experiment for everyone to play with.

Let's say, for the sake of argument, that a Spinward Courier (5G or 6G variant) has been contracted for gas giant to mainworld fuel tanker services and that the mainworld is not a moon of the gas giant (so different solar orbits).

As a fuel tanker, the Spinward Courier in tanker service would be transporting a full (external) fuel tank to the mainworld and returning to the gas giant with that same (external) fuel tank empty, so as to fill it up again at the gas giant for the next fuel run.

What other commodities besides L-Hyd fuel could be transported in that same external fuel tank from the mainworld to an outpost near the gas giant?

As anyone in the trucking industry knows, you make more money by hauling around trailers that are full than you do hauling around trailers that are empty. Transporting a load of cargo only half the time makes you a lot let profitable.

So ... what else could be transported in an external fuel tank to an outpost that wouldn't require modification of an external L-Hyd fuel tank?



My opening bid would be ... liquified gases (nitrogen, oxygen, etc.) used for industrial processes and life support systems that are slowly lost to space from space habitats. I suppose that liquified organic chemical compounds and volatiles (methane, etc.) might also qualify for various industrial uses at the outpost, particularly if there is ongoing construction at the outpost meaning an ongoing demand for supplies that cannot be sourced in situ at the gas giant. Just need to be able to "purge" the contents of the external tanks both before and during orbital fuel skimming of the gas giant so as to avoid contamination of the starship fuel to be transported.

Anyone else have any better ideas?

 

[Condottiere]

It helps that spacecraft performance is tied to volume, not weight, which means empty or full, the operating costs are the same, though the fees may not be.

 

[whartung]

Anyone else have any better ideas?

Just put a hatch on the thing and fill it with Skittles, Snickers, Beef Jerky, and other fine foods. Anything that can weather sustained high-G acceleration. Use extra layers of bubble wrap for when they go bouncing off the inner hull during maneuvers.

 

[Silverhawk]

Just put a hatch on the thing and fill it with Skittles, Snickers, Beef Jerky, and other fine foods. Anything that can weather sustained high-G acceleration. Use extra layers of bubble wrap for when they go bouncing off the inner hull during maneuvers.

The trouble with that is there may be residual hydrogen in the tank. Rail tank cars today are not used to carry something else in the reverse move. So a tank car carrying Corn Syrup that is 'empty' may have a residual amount after unloading. It is therefore unsuitable for hauling anything else. For comparison boxcars can be cleaned and haul a different commodity. There is a pool of boxcars under the branding Railbox. Their slogan was "Next Load and Road".

US Federal regulations allow for a tank car containing up to 5,000 gallons (volume varies based on specific commodity) as being moved as an 'empty' car.

 

[Spinward Flow]

The trouble with that is there may be residual hydrogen in the tank. Rail tank cars today are not used to carry something else in the reverse move. So a tank car carrying Corn Syrup that is 'empty' may have a residual amount after unloading. It is therefore unsuitable for hauling anything else. For comparison boxcars can be cleaned and haul a different commodity. There is a pool of boxcars under the branding Railbox. Their slogan was "Next Load and Road".

US Federal regulations allow for a tank car containing up to 5,000 gallons (volume varies based on specific commodity) as being moved as an 'empty' car.

That's kind of where I was going with that question.
I can imagine that the L-Hyd tanks could be flushed with another liquid (such as L-Ox or L-N as specified) for transport in the other direction, or could even potentially carry H₂O (presumably frozen/liquid/gas due to space environment transport conditions varying) where the limitation is more mass than volume (L-Hyd is relatively low density compared to H_{2O) ... but that's the thing, you have to be able to purge the tanks before filling with this next load for transport and liquids get tricky on that point. Note that my initial speculation of round trip fuel tankage runs were on a full/empty transport cycle, since D'Ganzio is both a poor and a desert world (hydrographics: 0) and therefore not a "rich" source of industrial chemical feedstocks to transport outbound from D'Ganzio to an outpost around a gas giant. Just wondering if there was a way to make a profit on both arcs of that circuit. I know that the starship fuel tanker part of it can be lucrative on the inbound leg from the gas giant ... but the outbound leg is looking like it would only be operating at a loss (no profit, but expenses continue).}

 

[whartung]

The trouble with that is there may be residual hydrogen in the tank.

We'll just handwave all that "exposed to the vacuum of space" stuff and skip to the part where it seems you missed the whole "bubble wrap" thing.

Pretty sure I wasn't expecting them to pour bulk Skittles in to the tank, but rather just toss in crates of whatever.

It's a big hole in space. With base criteria of them using containers that won't mar any interior insulation (perhaps, even, maybe, bubble wrap!), anything that fits through the unspecified size hole in the tank should be good. Going to swag a guess that if this is the plan, then the hole in the tank will likely be larger than a few centimeters, perhaps even man sized. Heck, they can just spin off the bolts and take an entire end off of it.

The opportunity of having the big, empty hole going back to someplace far away with consumers would likely prompt all sorts of innovative ideas by crafty folks trying to get products to market.

Recall the Good Ol' Days(tm) when we'd stuff junk plastic back in to the otherwise empty containers heading back to the Far East.

I reckon they hosed those out before packing them up with VCRs and box fans and shipping 'em back to us.

 

[Condottiere]

In theory, if you double wrap the hydrogen, primarily the fuel tank, secondarily with the fuel bladder, the tank is clean when you retract the fuel bladder; fuel bladders cannot supply jump fuel directly.

Of course, they're meant to be used in the cargo hold, so it's more an option if you want to free up additional cargo space.

 

[Spinward Flow]

In theory, if you double wrap the hydrogen, primarily the fuel tank, secondarily with the fuel bladder, the tank is clean when you retract the fuel bladder; fuel bladders cannot supply jump fuel directly.

Of course, they're meant to be used in the cargo hold, so it's more an option if you want to free up additional cargo space.

Now that's a good point.
I hadn't considered the possibility of putting an inflatable fuel bladder into a L-Hyd drop tank as a "flex use" option. Doing so would reduce fuel tankage transported by 1% (per bladder) while allowing different types of liquids to be carried without needing to clean/flush the tanks. If the tanks are designed to be opened (giant hatch on one end) then the inflatable bladder system would even allow the "flex use" of carrying solid cargoes, rather than just liquid ones, on fuel tanker runs between a gas giant+outpost and a mainworld.

Good thinking ... both inside and outside the box!

 

[whartung]

Yup, fuel bladder is a fine idea.

 

[Spinward Flow]

Yup, fuel bladder is a fine idea.

You still need the L-Hyd drop tank to put the fuel bladder "into" so it has some structure around it for containment under acceleration. But it does allow you to "flex role" the L-Hyd drop tanks for something other than just fuel tankage exclusively with relatively few issues, allowing them to transport other types of cargo when making a fuel tanker circuit around a system and being stuck with a single commodity to transport is sub-optimal.

 

[whartung]

You still need the L-Hyd drop tank to put the fuel bladder "into" so it has some structure around it for containment under acceleration.

Well, naturally. That's what we were talking about right? A full fuel tank coming from the outer system needing to be sent back and, hey, by the way, can we stuff some arbitrary cargo in them for the trip back out.

 

[Condottiere]

In the meantime, they've developed a dual use fuel tank/cargo hold, which you could use for jumping, but I'm a tad sceptical on the clean up.

 

[Spinward Flow]

In the meantime, they've developed a dual use fuel tank/cargo hold, which you could use for jumping, but I'm a tad sceptical on the clean up.

Theoretically yes, I suppose (on the jumping part), but the jump constraints are a tonnage less than 1/10th the maneuver only limitations.

A Spinward Courier (5G or 6G) is Jump-2 in a "clean" configuration, but with external cargo can only manage up to 97 tons of external loading while still being able to manage Jump-1.
That's a big difference from a 1160 ton external tank (5G -> 1G, Jump-0) or a 1450 ton external tank (6G -> 1G, Jump-0).

Although ... {squints harder} ...
Oh dear ... why didn't I see THAT possibility before ...

97 * 12 = 1164
The 5G TL=11 version has a 1164 ton maximal external loading capacity.

97 * 15 = 1455
The 6G TL=13 version has a 1455 ton maximal external loading capacity.

So if standardization on a L-Hyd drop tank/cargo container with maximal flexibility between small and large displacements for both interstellar and interplanetary operations is concerned, what you wind up with is:
97 ton L-Hyd tank (MCr 0.107 each) with a 96 ton Collapsible Fuel Bladder inside (MCr 0.048) = MCr 0.155 each

12 * 0.155 = MCr 1.86 for a full set of 12 for the 5G TL=11 version (12*96=1152 ton fuel/cargo capacity)
15 * 0.155 = MCr 2.325 for a full set of 15 for the 6G TL=13 version (15*96=1440 ton fuel capacity)

Compared to a single external 1160 ton L-Hyd drop tank (MCr 1.17) or a single external 1450 ton L-Hyd drop tank (MCr 1.46) without internal fuel bladders, there's definitely a premium being paid on the more flexible duplicates of smaller tanks option.

But if you put fuel bladders into the standard (single) drop tanks, things change slightly.
99% of 1164 = 1152.36
1164 ton single L-Hyd drop tank (MCr 1.174) with a 1152 ton Collapsible Fuel Bladder (MCr 0.576) = MCr 1.75
99% of 1455 = 1440.45
1455 ton single L-Hyd drop tank (MCr 1.465) with a 1440 ton Collapsible Fuel Bladder (MCr 0.720) = MCr 2.185

So the "premium" being paid for stacking a lot of "jump capacity" tanks versus a single "interplanetary only" tank with Collapsible Fuel Bladders in the tanks winds up being:

• No difference in displacement tonnage (1164->1152 vs 1164->1152) in the 5G case, and (1455->1440 vs 1455->1440) in the 6G case.
• Slight difference (12*0.155=MCr 1.86 vs MCr 1.75) in the 5G case, and (15*0.155=MCr 2.325 vs MCr 2.185) in the 6G case.

That means the "premium cost" of using multiple 97 ton tanks (12x or 15x) instead of a single tank (1164 or 1455 tons) amounts to a difference of ... Cr 110,000 in the 5G case, or Cr 140,000 in the 6G case ... a "paltry sum" compared to the profit potentials on offer in even One Way Tanker™ circuit service contracts.

Additionally, the multiple 97 ton tanks "solution" (12 or 15 for 1G towing) is something which is "jump ferry" capable without needing any sort of space industry support at the destination for final assembly, only at the point of construction ... meaning that such tanks could be shuttled in and out to a different star system for annual overhaul maintenance if absolutely necessary. This simplifies and streamlines logistics tremendously, while standardizing on a "container module" for these Spinward Courier starships which is inherently more flexible (can tow fewer tank modules for a higher acceleration performance). It also creates a condition where the smaller 97 ton tanks can be more easily handled by more austere/poorer facilities and a logistical rotation can be set up in which a surplus of tanks cycle through a maintenance process to verify their engineering hasn't been compromised during transit. The 97 tons tanks are also simpler to warehouse, if necessary, as a reserve capacity in case of need, which can be used both in-system and to respond to disaster conditions in neighboring systems if the need arises for disaster recovery support.

Very interesting ...

You see ... even *I* am still learning all of the potential edge cases for turning a profit with these low end ships.
So much so, that I'm starting to think that all these ideas are worthy of a "Merchant Crown Prince" ...