The Islands were built as floating terraforming tools, vast complexes of mobile structures built for a single purpose: To seed the oceans of inhabitable planets with a bioreactor, prompting the required oxygenation event that'd make these worlds habitable within mere decades.
Structurally, they built on tried designs: Like
some of the oil platforms that were built on Earth centuries earlier,
The Islands essentially consisted of thousands of hexagonal prisms cast from local ferroconcrete to become the floatation devices and construction basis upon which equipment was later mounted. Including these concrete bases, the average
Island was designed to displace in the region of 15 megatons, becoming some of the largest man-made objects to be built on the surface of other planets.
To remain adaptable in the terraforming process and to easier serve in later use,
Islands were built from dozens of individual structures, each constructed with an identical highly self-sufficient fusion-based power system and ruggedized motive system that allowed slow but steady movement across the seas. Invariably, the equipment mounted on top would be environmentally sealed to ease work for the hundreds of people who served on them.
Most
Islands were taken apart after filling their purpose; their power systems in particular tended to serve for long times as generators for outlaying villages and bases established on the very same worlds, while the concrete structures themselves were often sunk as breakwaters at new-built ports or even served as pillars for bridges across coastal waters.
Islands came in any number of configurations during their usage; often more dependent on how many places on the planet were seen concurrently as optimal, only a number of standard configurations could be made out.
The IslandThe standard configuration of an
Island consisted of 35 mobile structures semi-permanently linked together, resembling an oval of over one kilometer length on its longer side.
The vertical construction of each mobile structure was highly similar:
Level 1-3 : Lower Concrete Structure, empty
Level 4 : mounting 40-ton fusion generator and 20-ton motive system
Level 5-7 : Upper Concrete Structure, filled with 662 tons "tankage"
Level 8 : equipment deck, containing six 65-ton linkage systems and other equipment
Level 9-10: top levels
The "tankage" employed consisted of bundles of insulated tubes, forming hundred of kilometers of length lit by high-powered lamps within its insulation, within which water was circulated and algae and plankton would be grown. This "tankage" was used for the main purpose of the
Islands: fast-growing genetically modified biomass from imported dry seed to the point where it could be flushed into the ocean. Further "tankage" would be installed topside on Decks 8-10 of over half of the
Islands structures.
Three of the structures of the island formed its spaceport, covered entirely directly above deck 8 with blast-resistant landing decks that gave the
Island enough room to even accomodate multiple dropships, a capacity rarely used.
Buildings covered a number of the structures; while each structure did have its own simple accomodations for the crew, there was typically a housing complex mounted over three structures, providing small individual apartments for the
Islands nominal 4300-strong crew, as well as housing a number of passengers; the other a similar-sized combined functional bloc that housed both cargo bays for spare parts and communications and control equipment along with the officer's housing and a small separate aviation facility.
The remaining structures - forming a 60m-wide spacing between topside tankage and landing decks - were often seen to be used to stow bulk cargo or containers; some islands were seen to carry up to ten-thousand containers stacked on this open space.
StatsNumber of Mobile Structures: 35
Modular Structure Linkage Systems: 6 per structure
Type: Fortress, Hardened
CF: 130
Hexes covered: 665
Structural Height: 10; 5 levels underwater
Motive: Naval
MP: 2.0
Equipment mounted across
Island:
26,600 tons - Power Systems (665 hex individual, fusion)
13,300 tons - Motive Systems (665 hex individual)
8,645 tons - Environmental Sealing (665 hex individual)
13,650 tons - Modular Structure Linkage (210 systems)
28,500 tons - Landing Decks (3x 19-hex)
1,000 tons - 2x Helipad
800 tons - 4x Small Craft Bay
800 tons - Light Vehicle Bay, x16 (50-ton boats deployed by Lift Hoists)
200 tons - Light Vehicle Bay, x4 (Cargo Handling Vehicles for Top Deck)
30 tons - Distributed Communications Equipment (on two structures)
12 tons - 2 MASH centers with 1/4 operating theaters
18 tons - 6 Field Kitchens
455 tons - 455 maritime lifeboats (in drop chutes on Deck 8 edges)
96 tons - 32 Lift Hoists
28,000 tons - Quarters, 2nd Class (4000)
9,000 tons - Quarters, 1st Class ( 900)
519,330 tons - Discretionary Insulated "Tankage"
114,000 tons - Open Cargo / Container Cargo
40,064 tons - Spare Parts and Small Cargo (Deck 8 Stowage)
60,000 tons - typically unused free capacity, on tankage structure edges
Other ConfigurationsA smaller configuration seen occasionally splits the above standard configuration into three identical smaller units of ten structures, leaving five tankage structures behind when performing other tasks such as when aquafarming bays and other inshore areas to create a wider maritime biosphere. Similar configurations, sometimes more spread out, have seen use as cargo turnover bases for airships seeding larger islands or less accessible small continents.
The largest configuration of
Islands once saw three of the above standard configurations joined up, forming a 46-megaton Megastructure for over fifteen years while its components were disassembled.
Edit: And just to confirm, yes, the standard configuration covers four mapsheets.