Navy Logistics

[Sageryne]

Hi all,

I recently posted about tugs. This morning, I was greeted with a new video by the Drachinifel YouTube channel talking about US Navy logistics during WWII.

The Battle in the Pacific has many parallels to space warfare. The distances are long. There are very few (heavily defended and valued) locations to base ships out of (islands in the Pacific, planets in Traveller).

Drachinifel does a great job talking about all the OTHER ships you need besides warships:

- Tankers (not everyone has the time or capability to skim and/or refine fuel)
- Ammunition ships (missiles get used up quickly)
- Logistics ships (food and other consumables) - including refrigerated ships that can produce ice cream!
- Hospital ships
- Repair ships
- Tenders for smaller vessels
- Travelling drydocks to repair damaged vessels
- Fleet Tugs
- Unpowered barges to provide forward storage of supplies
- Barracks Ships for replacement crews

While I realise these sorts of ships are not quite as sexy or exciting as warships, they are just as important.

One specific vessel that might be right there on the front line are the fast combat support ships. These combine the roles of tanker, ammunition resupply and refrigerated logistics vessels into one, with the same speed and range as the fleet. They travel with the battleships, carriers and cruisers, refuelling them, providing food, replacement missiles/sand canisters, supplies etc.

They would have defensive weaponry (to protect against fighters and small gunboats).

They would also be a priority target for the enemy, because they were more lightly built and armoured and represented a weak link.

- Kerry

 

[Condottiere]

It's a mix.

One famous example is the supply train in Russia, slow but steady.

Or riverine and littoral civilization.

The Royal Navy used a series of bases within range of each other, for their logistical backbone, and if you translate that to Traveller, that could be a line of bases within three parsecs of each other.

 

[rinku]

One significant type that may appear in a Traveller navy is the refinery ship. Optimised to scoop a gas giant and refine the fuel, then deliver it to the rest of the fleet (or to fill up tanker ships that do the actual delivery). Possibly more of a tender, with non-jump ships doing the actual scooping.

 

[EccentRick]

I would appreciate if someone could help me understand the role of a refinery ship and how it fits in an Imperial fleet, because I keep hanging myself on the math. When I try to work the figures these ships always seem to come out a size group bigger than the ship they are attempting to refuel, just to support one ship.

At J4 over half of the ship is dedicated to its jump drive and own jump fuel (40% fuel, 10%+5 tons for the drive). The maneuver drive is another % equal to its rating, so probably between 4-6%. If another 40% is for the carried fuel for ONE ship of the same size (carrying less means repeated visits to top-off), we are left with somewhere around 5% of the ship for the power plant (and fuel to run it), fuel refineries, crew, defenses, etc.

Fuel carriers become so much larger (and bigger targets) than the ships they support, and/or so numerous a % of the hulls of a fleet (even before adding hulls carrying additional munitions or other supplies)

A fleet operating at J2, perhaps J3, has more space to figure out the efficiency curves and trade-offs, but I just struggle to see how a J4 fleet is better served by having fuel tender/refiners around instead of setting each ship up (either in itself or through support craft) to skim and refine its own fuel.

Personally, I'm settling in on a 2-day target for the fuel refineries, and (for all their other math errors) I have a vague sense that most recent published ship designs also ballpark in this area. For a J4 hull carrying 1% of the hull tonnage in refineries will accomplish that rate, which 'feels' like an inflection point of efficiency (as well as a convenient and easy calculation), while dropping to 0.8% of the hull stretches the refinery time to 2.5 days and 2/3 of 1 percent of the hull corresponds with a 3-day window. Also conveniently easy math from a 2-day J4 mark: it takes 1/2 of a day to refine the fuel needed for 1 parsec. The full 2 days are only needed for J4 after a J4, the ship will have enough refined fuel to make a J3 after a J3 in one day and can finish refining the last parsec's worth of the fuel in jump-space.

 

[Terry Mixon]

I would appreciate if someone could help me understand the role of a refinery ship and how it fits in an Imperial fleet, because I keep hanging myself on the math. When I try to work the figures these ships always seem to come out a size group bigger than the ship they are attempting to refuel, just to support one ship.

At J4 over half of the ship is dedicated to its jump drive and own jump fuel (40% fuel, 10%+5 tons for the drive). The maneuver drive is another % equal to its rating, so probably between 4-6%. If another 40% is for the carried fuel for ONE ship of the same size (carrying less means repeated visits to top-off), we are left with somewhere around 5% of the ship for the power plant (and fuel to run it), fuel refineries, crew, defenses, etc.

Fuel carriers become so much larger (and bigger targets) than the ships they support, and/or so numerous a % of the hulls of a fleet (even before adding hulls carrying additional munitions or other supplies)

A fleet operating at J2, perhaps J3, has more space to figure out the efficiency curves and trade-offs, but I just struggle to see how a J4 fleet is better served by having fuel tender/refiners around instead of setting each ship up (either in itself or through support craft) to skim and refine its own fuel.

Personally, I'm settling in on a 2-day target for the fuel refineries, and (for all their other math errors) I have a vague sense that most recent published ship designs also ballpark in this area. For a J4 hull carrying 1% of the hull tonnage in refineries will accomplish that rate, which 'feels' like an inflection point of efficiency (as well as a convenient and easy calculation), while dropping to 0.8% of the hull stretches the refinery time to 2.5 days and 2/3 of 1 percent of the hull corresponds with a 3-day window. Also conveniently easy math from a 2-day J4 mark: it takes 1/2 of a day to refine the fuel needed for 1 parsec. The full 2 days are only needed for J4 after a J4, the ship will have enough refined fuel to make a J3 after a J3 in one day and can finish refining the last parsec's worth of the fuel in jump-space.

That’s an interesting point. I’ve always aimed for 1 day refining capability. I figured they’d want faster turnaround. Thanks for provoking my thought in that area.

 

[Condottiere]

Depends on the local tactical and operational situation.

If you're fairly sure that the nearest gas giant isn't booby trapped, you could let your entire line of battle go skinny dipping.

And if you're not, and have time to spare, you send in the (fuel) drones.

 

[Sageryne]

To me, the idea is keeping the warships on station. Yes, each ship should have its own scooping and refining capability to keep them independent. Once they jump in system, then having a specialist ship that can skim, refine and bring the fuel to the warships means they don’t have to leave their station. It also means that after initial refuelling, the tanker can top up the fuel they use to run their power plants so they are ready to jump at a moment’s notice.

I also like the idea of keeping the refinery ship in orbit and sending virtually piloted fuel skimmers into the gas giant’s atmosphere.

 

[Sigtrygg]

10,000,000 ton refueling tender/drop tank refinery and manufactory. This is a fleet support vessel.
50% internal fuel tanks.
It carries dippers, huge ships that dive into gas giants, crushers (ships equipped with mining drones to cut chunks off asteroids and comets), fuel refineries and drop tank fabricators.

Smaller 1,000,000 ton versions are also available as squadron support vessels.

 

[Sageryne]

I like the way you think. BIG!

 

[CordwainerFish]

One significant type that may appear in a Traveller navy is the refinery ship.

Just, whatever you do, don't name one Nostromo.

 

[Condottiere]

 

[Vormaerin]

Naval logistics in Traveller are quite interesting and difficult to find any kind of historical comparison to. Half the fuel capacity (or more) of a tanker ship ends up going to moving the tanker itself. I don't think there's ever been anything remotely like that IRL. Maybe when you talk about wagons and how after a certain point the draft beasts consume too much food themselves to make them useful for transport?

The Navy rulebooks are called High Guard presumably because the role of guarding refueling ships (aka High Guard) is a major element of naval logistics and training evolutions. On board refineries in Traveller are so efficient I'm not sure that fuel tankers actually exist as a meaningful element of fleet operations. The amount of tankage you would need is, as pointed out above, simply massive. And the guardships for them likewise a drain.

I think gas giant refueling is with each vessel having its own onboard refinery is, in fact, the default.

 

[rinku]

I think gas giant refueling is with each vessel having its own onboard refinery is, in fact, the default.

I agree, and squadrons on patrol or routine redeployment would need nothing else. Those have the luxury of time to refuel, and you definitely don't want a warship to be stranded when things go wrong. Although a fuel scoop is all that's needed - the refinery just makes the fuel refined, and it might be an acceptable risk for a warship to jump on unrefined fuel in an emergency. But as a ship component, refineries aren't that expensive or much of a volume overhead.

Operational squadrons would often need tankrons to speed things up. That's seen in practice in the 5FW game and its rules for such tactics.

Naval bases would benefit from purpose built fuel ships, up to and including refineries (which could be anything from a tanker with refining capacity to a space station) that are deployed to them. Maybe in most cases the refinery is just a fixed part of the naval base, but mobile operations would surely come up sometimes?

 

[Condottiere]

Fuel, spare parts, ordnance, food and beverages.

 

[MasterGwydion]

Tooth to Tail ratio in current times is roughly 1 combat unit for every 5 to 8 non-combat units of equivalent size. This would be more for the Army or the Marines though. Best I can find for the Navy is an average of 1 or 2 support ships for each destroyer or cruiser. Obviously, this number increases for Carrier Battle Groups and Amphibious Operations. No idea if this helps anything in this discussion.

 

[rinku]

It doesn't hurt. And keeps things lined up with the technology side of things.

Space navies potentially have less of an ammunition train too, depending on YTU and how important energy weapons are vs munitions.

Although being able to fabricate missiles is another possible function of a space navy support ship.

 

[Sageryne]

It doesn't hurt. And keeps things lined up with the technology side of things.

Space navies potentially have less of an ammunition train too, depending on YTU and how important energy weapons are vs munitions.

Although being able to fabricate missiles is another possible function of a space navy support ship.

Hi Rinku,

That is an awesome idea. Instead of ships carrying "consumables," you could have a fabrication ship carrying a TL15 fabricator and a ton of raw materials. That way, you can make the specific items the fleet needs at any one time rather than carrying a huge amount of supplies. You could also have mining drones that would allow the ship to pull up next to an asteroid belt and mine the raw materials on site.

I am reminded of the new Battlestar Galactica series. They were short on fighters until they met the Pegasus, a Mercury-class battlestar. "The Mercury-class also features fighter production facilities to allow it to produce spare parts for its fighter squadrons or even wholly new fighters, even if detached from support ships, provided with the suitable materials."

It makes sense to be able to manufacture new fighters as they would be more frequently lost in combat.

However, that might also require barracks ships carrying replacement pilots and possibly training ships with simulators and fighter launch/recovery capability.

In addition, I was thinking you might have agricultural ships, with hydroponics (for fruits and vegetables) and carniculture vats (for meat). This would supply the fleet with fresh food during deployments.

In peacetime (or on extended campaign for that matter), the fabrication ships and agricultural ships would be useful for establishing and expanding new colony worlds, especially navy bases. You could park them in orbit (or land them, depending on how they are built) and supply everything necessary for the new base.

- Kerry

 

[Terry Mixon]

Hi Rinku,

That is an awesome idea. Instead of ships carrying "consumables," you could have a fabrication ship carrying a TL15 fabricator and a ton of raw materials. That way, you can make the specific items the fleet needs at any one time rather than carrying a huge amount of supplies. You could also have mining drones that would allow the ship to pull up next to an asteroid belt and mine the raw materials on site.

I am reminded of the new Battlestar Galactica series. They were short on fighters until they met the Pegasus, a Mercury-class battlestar. "The Mercury-class also features fighter production facilities to allow it to produce spare parts for its fighter squadrons or even wholly new fighters, even if detached from support ships, provided with the suitable materials."

It makes sense to be able to manufacture new fighters as they would be more frequently lost in combat.

However, that might also require barracks ships carrying replacement pilots and possibly training ships with simulators and fighter launch/recovery capability.

In addition, I was thinking you might have agricultural ships, with hydroponics (for fruits and vegetables) and carniculture vats (for meat). This would supply the fleet with fresh food during deployments.

In peacetime (or on extended campaign for that matter), the fabrication ships and agricultural ships would be useful for establishing and expanding new colony worlds, especially navy bases. You could park them in orbit (or land them, depending on how they are built) and supply everything necessary for the new base.

- Kerry

One thing to remember about fabricators is that they are extremely expensive, take time to make each item, and have tech level build limits.

1. A 100-chamber liter tech level 13 enhanced fabricator costs MCr5 according to the Central Supply Catalogue Update 2023. That can fabricate something about the size of an Aslan. For some parts, you will need something perhaps a lot more expensive. At KCr50 per additional chamber liter (adding a 10%-60% premium for units larger than 100 chamber liters, that can pile up fast for a really big one.

2. You might ask why that matters when the Navy can afford it. Well, at that tech level, it takes a base time of 1 hour per fabrication. In addition, allow me to quote the book for added times.

Brains, biological or robotic, and their ‘neurological’ connections quadruple construction time and complex, highly irregularly shaped objects and objects requiring high melting temperatures and cooling, such as crystaliron and certain other metals, will also double fabrication time, meaning a highly complex electronics-laden item like a robot may require as much as eight times the listed time period to be ready for extraction.

That will tie up a fabricator for a while. You'd need a lot of them and big ones, too, most likely.

3. The tech level 15 enhanced fabricator is limited to only making items of tech level 13 or lower. For a tech level 15 Navy, that's problematic. Let's say it is built on Vincennes. That lets it fabricate tech level 14 parts, but that's still lower than the advanced ships need.

How to get around that. Well, you could have Vincennes build a prototype tech level 17 advanced fabricator. As they are tech level 16, that puts it well into striking range. That would be even more pricy and have some quirks to deal with. A prototype like this is x5 the cost (maybe 10x depending on the quirk rolled) and has a quirk that is randomly rolled. The Navy might not like that.

The fabrication time is the same as for the enhanced fabricator but as a prototype advanced fabricator, it could make tech level 16 components, so they might be willing to accept the negatives. It does come with a DM-1 to use, and that will likely impact the thinking as well.

Not saying the Navy would say no, but it isn't as much of a no brainer as it might otherwise seem.

 

[Sigtrygg]

Just use T5 makers instead since they exist in the Third Imperium, trouble is they have yet to be detailed in a Mongoose supplement for some reason. Unless the powers that be declare Agent of the Imperium to be non-canonical.

 

[Terry Mixon]

Just use T5 makers instead since they exist in the Third Imperium, trouble is they have yet to be detailed in a Mongoose supplement for some reason. Unless the powers that be declare Agent of the Imperium to be non-canonical.

Or they decided that the fabricators were their version of them.