How fast (or easy) is it to swap hull modules?


How quickly can the different modules of a modular hull be changed, and what (if any) facilities are needed?

The biggest examples of the use of modular hulls are:
The Modular Cutter (TL 12) from High Guard; 1x 30 ton module (60%) (note: also the only modules small enough for cargo cranes)
The Kokirrak Dreadnaught (TL 15) from High Guard; ?x modules =5,800 tons (3%) (described as cargo modules)
The Element cruiser family (TL 15) from its book/box (with the Ghalalk also in High Guard); 2-6x 2,600 tons (21%)
The Steppehauler (TL 16) from JTAS 6; 2x 500 ton modules (71%)
I am attempting to extract guidance from the section on Refitting ships. If modularity does not provide advantages over refits, there is little incentive for the costs. Swapping a module should not take longer than it would take a refit to replace what was in the space, since the point of a module is to avoid having to perform all that work on the ship by having the different end-states already ready in the different modules, so comparisons should be made to the time needed for minor refits.

In that vein it seems the time and effort ought to be the same for all modules used by the class, regardless of the module’s configuration, and multiple modules (e.g. Element Cruisers) can be swapped simultaneously. Refit time is based on construction time, which is based on the cost of the ship (for current purposes to establish a baseline, I’m ignoring reductions based on shipyard TL). Construction time is 1 day per MCr, major refits take 25% of construction time, and minor refits take 10% of construction time.

A modular hull increases the cost of the overall hull by the percentage designated as modular (or to simplify, as HG2022 shows in the stat blocks, after paying full price for the entire hull pay the cost again, CR50000 per ton, for the tonnage designated as modular) (again, for now ignoring cost effects of hull configuration)

While the hull cost of the module itself is half that of a regular hull, that pricing forms the start of price changes based on module configuration so I’m currently disfavoring it over the hull cost calculation for modularity for consistency between different module configurations.

This combination suggests a guideline of 1 day per 200 tons of module.
At 1 day per 200 tons;

The Modular cutter’s 30 ton module needs 0.15 days or 3.6 hours

A pod for an element cruiser needs 13 days.

A module for a Steppehauler needs 2.5 days

If all 5,800 tons of space in a Kokirrak Dreadnaught comprise a single pod, it would take 29 days. More likely there are multiple pods, but I was unable to find specifics.
The Element Cruisers book suggests that replacing the pods takes “several weeks”, and this qualifies, but it also feels a bit fast for the reported rarity of the cruisers actually changing modules during their service life, especially if TL adjustments to time are applied.

The modular cutter seems slightly on the long side, as it holds position as the quintessential example of modularity. In comparison, a non-modular ship of 50 tons undergoing a refit would require .18 days to refit 30 tons of acceleration seats (Personnel Transport module), or .06 days for Assault Boat configuration (8 tons acceleration seats, 20 tons digger blades). Cargo configuration (5 tons acceleration seats, .03 days) and Fuel skimmer (.1 day) being mostly empty storage space are so ‘quick’ they rarely would be the defining ‘longest job’ that sets the refit time.
As the only modules of these prominent examples that can be manipulated by cargo cranes, perhaps they qualify for some other acceleration factor.

The Steppehauler, essentially a much-oversized version of the cutter, has a similar feel. While each module is bigger than a Type R or corsair, and both combined are the size of an X-Boat Tender or Destroyer Escort, needing 2.5 days for a switch seems long for a craft with this activity as its sole designed purpose.

The modules are such a major portion of the modular cutter and steppehauler, if we add a twist of using the smallest of the various segments (module or ‘remaining’ non-modular hull) there is a slight reduction in the time:

Modular Cutter: base ship is 20 tons for 0.1 days (2.4 hours)

Steppehauler: base ship is 400 tons for 2 days

What are other opinions of these timeframes? Overly long? Too quick? Should there be other factors considered?
1. Modulation is a legacy feature, so it's mostly inertia.

2. Podularization probably was introduced as a gee whiz feature for new book and aspect in in Imperium naval construction and design, and neither elaborated on, and promptly ignored.

3. Time spent to install pods onto a primary hull might indicate if it's treated as a subsidiary hull, or integral to the primary hull.
The Modular cutter’s 30 ton module needs 0.15 days or 3.6 hours
Especially the Modular Cutter is designed to have the modules swapped at a regular base. Without any actual figures or formula I feel that this is too long. I would have said 30-60 minutes or 1D * 10 minutes timeframe if needed for a task.
Those estimates for the Modular Cutter and the Steppehauler look reasonable to me; the Element and the Kokirrak should probably take a little longer than that. But bear in mind that times like that are only going to happen if the port/yard already has the modules ready to install - if you're having to get them constructed, that's going to determine how long it takes. Which is probably the main reason the Elements don't swap out modules very often during their service lives - not many yards are going to keep spare Element modules waiting around in stock. Cutters are everywhere, so their modules (at least the more commonly used ones) are going to be widely available, but cruisers and dreadnoughts are much less common, and aren't likely to need to change their mission parameters anywhere near as frequently, so they'll probably only have the modules available at a depot/naval base for the most part. It does mean that with adequate planning, though, the next refit/refurb will probably go much quicker than a similar maintenance on a non-modular navy ship would.
You do have to disconnect the wiring and/or plumbing.

Unless, wireless and/or self contained ship systems.
Quick coupling is already a technology used in various fields, such as pressurised air supply for trailers or connection of garden hoses.
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It's probably circumstantial.

If it includes a turret with a bunch of fusion guns, you might be more careful with the electrical coupling.
My take on the modular cutter was always "changing the engine in a Leopard 1 tank". So this is not a 5min job and needs some external tools but with the right stuff and professionals can be done in less than an hour no matter what module and faster for some "stupid" (cargo only) modules
The Leopard 1/2 tanks would be TL7 and the Modular Cutter is TL12. I would assume that the technology to quickly exchange things would evolve in 5 tech levels. We are not talking about exchanging the fusion reactor or the M-drive, which would be the equivalent to the Leopard 1/2 Power Pack, but about specifically designed modules that are probably exchanged on a weekly or even daily basis.
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High TL do not make thinks faster or easier when it comes to load bearing connections and data / power couplings.
IMO, that statement is like applying 1920's thinking to today's tech.
After TL 9, grav plating renders load bearing weight meaningless when exchanging parts. You tune the local grav to zero or slightly negative, depending on what you need.
Self sealing and retracting couplings and lock bolts/clamps eliminate the need for manually disconnecting/reconnecting fittings, seals and connectors.
A high tech version of a fork lift with articulated arms would be able to move any size module (slowly and carefully) under the above conditions in fairly short order.
This is like a pair of 19th century engineers arguing about how things will be working in 2050 except way worse because it is an even wider tech level gap between now and the Third Imperium than between the 19th century and the 21st century.

It is going to work however you want to work, because it probably won't look anything like either side imagines when it is actually a reality.
(there's no way a heavier-than-air motorised machine will ever fly - you just can make the boiler light enough)

Or as the New York Times said (editorial: Oct 9th, 1903):
" might be assumed that the flying machine which will really fly might be evolved by the combined and continuous efforts of mathematicians and mechanicians in from one million to ten million years — provided, of course, we can meanwhile eliminate such little drawbacks and embarrassments as the existing relation between weight and strength in inorganic materials.”

Really, though, I imagine the cutter module doesn't require more than the time required for a docking x2 to remove/replace a module, but a Element-class cruiser might take a full shipyard a week or more, just because of the module's mass and number connectors and quality checks required.

'Modular' means different things to different advertisers people. A truck carrying a container is technically modular - both because of the container and because the front part detaches (okay, sorry, not at all a mechanic). The new US littoral combat ships, Danish frigates(?) and ships are theoretically modular, but more like in that Element-class category.
From the original introduction to the Broadsword, JTAS #8 in 1981, a Cutter module swap in open space is about 7 minutes plus however long it takes to get from the first to the second.
Detach in open space - 2 minutes
Attach in open space - 5 minutes

Both operations are 2 minutes each in a guided environment like the cutter wells of the Broadsword, but getting in and out the wells is *also* five minutes each.

So yes, very much like Thunderbird 2, without the legs thing.

The Element, Kokirrak, Plankwell, Salamander, and a few others are different; they're "shipyard modular" instead of hot swappable.
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