also see Fleet Composition
(1) Alpha systems (class A star port & high pop & high tech) have the capacity to create large fleets of large ships.
(2) Alpha clusters, an alpha system and its hinterland generally represents 95%+ of the wealth of a sub-sector.
(3) Alpha clusters are the core of the 3I and they and the routes between them are what the fleets protect.
(4) Refueling large fleets of large ships is a major pain.
Under Traveller rules large fleets of large ships require huge amounts of fuel.
For example a squadron of 500k dton battleships would use 800k dton of fuel for a single J2 jump and at 500Cr per dton of refined fuel that would be 400 million Cr.
Obviously the navy would have its own refueling depots but it gives an indication of the scale of infrastructure needed to support the huge tonnage of the main battle fleets.
The refueling issue keeps the main battle fleets in their home system in peace time leaving peace time patrolling to smaller ships
- silk road trade routes to cruisers
- hinterland cluster patrols to the much smaller colonial cruisers
- backwater systems to the Scouts and the occasional colonial corvette.
Fuel sources like gas giants are often guarded by an orbital station or SDB.
Systems acting as refueling stops along the long distance “Silk Road” trade routes between alpha clusters have naval orbital stations providing fuel for naval patrols and fighter escorts for merchants.
The IN is organized by sector.
There is a sector fleet admiral for day to day operations but imtu the sector Duke is the CinC and technically can take direct command although this is rare.
The sector fleet is divided into colonial fleets and reserve fleets.
Each sub-sector collects a navy tax of which half goes to the sub-sector Duke for the colonial fleet and half goes to the sector Duke for the sector fleet.
Defense is based on the hedgehog principle where each sub-sector’s colonial fleet acts as a strong point defending its own sub-sector (although in reality colonial fleets tend to focus on the sub-sector’s alpha cluster).
The reserve fleets provide the mobile component that maneuvers around the strong points.
There is one named colonial fleet for each sub-sector.
The colonial fleet has a commanding admiral but imtu the sub-sector Duke is CinC and can take direct command although this is rare.
Technically colonial fleets can be ordered out of their sub-sector by sector fleet but rarely are.
The colonial fleet includes fixed defenses like orbital stations and planetary bases, SDBs and trade lane patrols as well as the mobile colonial fleet.
The size and composition of colonial fleets varies greatly.
There is generally at least one alpha system in each sub-sector and these systems will build the colonial fleet unless the TL is low in which case some of the ships will be bought from shipyards elsewhere.
Weak sub-sectors will have a minimal colonial fleet and need direct backup from the 3I.
The colonial fleets are mostly recruited from the sub-sector.
This is the name given to the official IN. The name comes from the colonial fleets providing the forward line of defense with the IN fleets held in reserve ready to be massed against any intruder.
The reserve fleets are numbered.
IN reserve fleets tend to follow set organisational patterns.
Some of the IN fleet types are: battle, assault, interdiction, strike, penetration, depot.
Reserve fleets come under the direct command of the sector fleet not the command of whichever sub-sector they are based in – although they can be assigned to a sub-sector command by sector fleet.
The reserve fleets are largely constructed in and recruited from the core.
Important systems can have substantial non jump capable defenses also – orbital stations, ground installation and SDBs.
Gas giants and other refueling sources are often very well guarded in this way.
Alpha clusters provide these for their own clusters.
The IN maintains the equivalent of a roman road type system with static defenses around the refueling points along the long distance trade routes between clusters.