Editing Codex Astartes (section)

====The Fleet====
A chapter is allowed a fleet of as many ships as it can get together, and may assign Marines to these ships as permanent staff in a similar fashion to the Armoury, although the Codex is significantly more flexible on Fleet staff. A chapter can be Codex-compliant without any Marines in their Fleet at all. Ship designations made for Space Marines have a fairly narrow band of marine transport capacity - one to three companies' worth - which does not change significantly between chapters. Therefore while a chapter could theoretically muster a fleet of any size, the practical and political restraints limit a chapter fleet's size. At the top end, the best is a [[Battle Barge]] for each company, another Battle Barge for a flagship and accompanying [[Strike Cruiser]]s, [[Adeptus Astartes Light Cruiser|Light Cruisers]] and [[Adeptus Astartes Escort|Escort]]s, plus whatever orbital defenses of the homeworld and the system fleet and maybe one or two mobile stations. This is stretching it for most chapters, though ancient and politically secure can have more than this and some chapters have different classes of ship as well. The Navy frowns upon Marines having too many [[Lance Weapon|Lance]]-equipped ships in particular. Fleet based Chapters obviously have more than usual, and one powerful vessel, possibly even a Warp-capable Star Fort, serves as the Fortress-Monastery.

*'''Master of the Fleet''': Often the Captain of the 4th company gets this position by default, but as mentioned above in the entry for Fourth Captain it's [[Uriel Ventris|not unheard of for a Captain to step down]] from the position if someone else would be better suited to the role: that person is titled "Lord Admiral" and gets command over the Chapter's fleet assets. It is perfectly reasonable that the Lord Admiral holds a battlefield rank of Battle-Brother or Sergeant, making him probably temporary until the Captain or his replacement wants the job back. As mentioned above, some Chapters (especially fleet-based ones) have this post be straight-up separate from the role of Fourth Company captain and have a dedicated full-time Marine as Master of the Fleet in the Chapter Council while the Fourth Captain gets different special roles.
*'''Lieutenant Commander''': In the days of the Great Crusade, these individuals commanded battalions of five companies, outranking Captains and subservient to Chapter Masters. We know of [[Marines Errant|only one example]] of this rank though it is uncertain whether the title holds the same authority as before. From what we know it now applies to the commander of a vessel, which makes sense since most Space Marine chapters have more ships than Captains, so ''somebody'' has to get the job of commanding them. Often assumed to be just a techmarine or sergeant of whichever squad gets attached to that vessel, or more likely a badass high ranking [[Chapter Serf]] who doesn't need to be superhuman to understand how spaceships operate. 
**With the advent of the company rank of Lieutenant, it is uncertain as to how the Lieutenant Commander actually fits in the new command structure. Is it a superior form of Lieutenant with new duties (which is what the rank itself implies) or is it a Lieutenant who has been officially combined with the Force Commander role (see above) and has his own units set aside from his company that he commands on a full time basis? More likely, considering that Space Marines tend to hold to an army chain of command rather than a naval hierarchy, the rank is probably an honorific title that stands alongside their company rank as with the Lord Admiral. It is also quite possible this is now the same as a old ''naval'' Lieutenant Commander, which was a ''Lieutenant'' serving as the ''Commander'' of a vessel.