Imperial Navy Hierarchy

The Imperial Navy utilises a rigid command structure, seemingly unified across this entire military branch, unlike their Imperial Guard counterparts, who have no standard organisation.

Flag Officer Ranks
Commissioned officers represent the highest ranks of the Imperial Navy personnel and their commissions usually can only be granted by the Battlefleet Administratum:

Lord High-Admiral of the Navy
A Lord High Admiral (also referred to as a Lord Militant Commander or Lord Commander) is the senior-most command rank within the Imperial Navy. Most of these senior commanders are selcted from the office of the Lord High-Admiral of the Segmentum Solar. The Lord High-Admiral of the Navy oversees the Imperial Navy's interests on the Senatorum Imperialis on Terra, while the five Segmentum Lord High-Admirals managed the fleet affairs.

Lord High-Admiral
Also called a Battlefleet Commander, Lord High-Admiral is the highest rank of the Imperial Navy. Only five of these august individuals exist, one for each of the Segmentae Majoris. Each is responsible for the Imperial Navy's fighting forces across thousands of sectors in their allotted portion of the galaxy, or in the case of the Lord High-Admiral Solar, the substantial volumes of space around Terra itself. Although all five Lord High-Admirals hold equivalent rank, traditionally the commander of the Segmentum Solar is considered the most prestigious office.

Lord Admiral
A Lord-Admiral, or Sector Commander, is responsible for all naval operations in a given sector and has direct command of units of the Segmentum battlefleet allocated to that sector.

Admiral

 * Solar Admiral - Solar Admirals are often prospective sector commanders waiting for assignment to a sector. As such opportunities are rare, it is far more common for Solar Admirals to be dispatched to warzones in command of a reinforcing fleet or kept busy on "special duties" with their own independent flotilla.
 * Admiral - An Admiral is allocated command of a portion of a sector's fleet and responsibility for the security of a handful of star systems and the vast tracts of wilderness space that lies in-between.
 * Vice-Admiral - By long tradition, a Vice-Admiral commands the leading division of a fleet, the part that would equate to the vanguard of a terrestrial force. In later times this has come to mean commanding a force of Light Cruisers and Destroyers charged with scouting for the enemy, charting navigational hazards and long-range patrolling.
 * Rear-Admiral - In ancient times when an entire Battlefleet might be massed together, the thousands of starships present would be divided into three commands, each under the command of their own Admiral. The Rear-Admiral was the youngest and least experienced flag officer in the fleet and so would be given charge of the rearmost division as the one least likely to see combat. Over time this flag rank has evolved into a largely administrative post charged with coordinating repair facilities, refuelling ships, forming convoys and other rear echelon activities. Time spent as a Rear-Admiral is seen as essential for a flag officer who aspires to higher ranks to demonstrate their facility with logistics and high-level planning.

Senior Commissioned Officers

 * Commodore - Also sometimes called a Group Commander, the rank of Commodore was originally only a temporary one given to a senior Captain placed in charge of a squadron of starships. Over time the rank of Commodore has found its way into permanent usage as what were once temporary squadrons stabilised into regular patrol routes and areas of responsibility. On rare and terrible occasions when capital ships join together in squadrons the senior Captain is still promoted to Commodore for the duration of the engagement.
 * Lord-Captain - Sometimes also referred to as Flag-Captain, Lord-Captain is an honourific rank normally applied to Captains who command vessels on detached duty.
 * Captain - Imperial Navy Captains are the masters of all that they survey. Aloof and uncompromising, these figures are unbowed by the awesome responsibility entrusted to them. These exceptional individuals hold full command of an Imperial Navy warship and all the souls that reside within it.
 * Commander - A Commander is a subordinate officer rank that is in charge of individual Escort-class vessels, with a Captain or Commodore holding overall command of an Escort squadron. However, an officer with the rank of Commander might also be found as the commanding officer of a squadron of system vessels, wing commander of the Attack Craft onboard a carrier ship, or placed in charge of an orbital station.
 * Lieutenant Commander -

Junior Commissioned Officers

 * Flag Lieutenant or Lord-Lieutenant -
 * Lieutenant (First, Second or Third) - A lieutenant is a junior commissioned officer who is usually placed in direct command of system-defence ships and monitors. It is more common to find Lieutenants acting as second-in-command aboard Escort-class ships, as part of the vast bridge crew found on a capital vessel, or in an Attack Craft squadron acting as a Flight Leader. A Lieutenant is regarded as having true potential and the opportunity for further advancement up the Imperial Navy's chain of command.
 * Sub-Lieutenant or Ensign -
 * Midshipman - A Midshipman is the junior-most "officer" rank in the Imperial Navy. Midshipmen are actually better described as students with an officer's rank. Technically afforded an officer's respect, they are nevertheless still in demanding training to become true officers, and many of their duties are "hands-on" opportunities to learn. Midshipmen are so-called because they traditionally have quarters somewhere in a warship's midsection, far from the command bridge.

Warrant Officers
Warrant Officers (also known in some quarters by the archaic term "Petty Officers") act as the equivalent of non-commissioned officers like Sergeants and Corporals in planet-bound Imperial Guard regiments. They disseminate orders from higher authority, ensure that those orders are carried out by the rank and file of enlisted ratings and maintain discipline with regular floggings. They are called Warrant Officers because their rank is created through the issue of a written warrant from either fleet administration or the captain of their warship. Warrant Officers occupy positions of trust on the ship and a Captain with even the most mutinous of crews can keep the ship running as long as he can rely on his Warrant Officers. It is common practice in the Imperial Navy to promote Warrant Officers from among the ratings already on board a warship, but large numbers of warrants are also issued to civilised worlds as part of their Imperial tithe of experienced personnel for the Emperor's military, often with a promise of reward to entice skilled individuals.
 * Ship's Master - The Ship's Master is generally the senior-most Warrant Officer and most experienced voidsman on board a given starship. Often the master is tasked with critical responsibilities, such as stellar navigation and the keeping of the starship's log. In addition, he or she might oversee the keeping of the ship's attitude jets, hangar decks, and stores and supplies.
 * Gun Captain - A Gun Captain is a highly respected non-commissioned officer who has the great responsibility of commanding a single gun crew on an Imperial warship. The Gun Captain is the foremost expert on performing all the duties of the subordinate ratings in his or her command and often achieves the post only after decades of working his or her way up through all the different enlisted ratings.

Non-Commissioned Officers

 * Master Chief Petty Officer -
 * Senior Chief Petty Officer'
 * Chief Petty Officer
 * Sergeant-At-Arms or Senior Armsman - A Sergeant-At-Arms is placed in charge of a squad of Armsmen anywhere between six and twenty-strong with responsibility for close action in naval combat (such as hit-and-run attacks and boarding actions). A Sergeant-At-Arms' greatest responsiblity is the keys entrusted to him for the weapons lockers found on every deck of a warship. When battle commences the Master-At-Arms signals the Sergeants to clear the decks and prepare for action, indicating at that time whether to arm the crew. Sergeants-At-Arms are often recruited via warrant or planets from among former Imperial Guardsmen to ensure they do not have prior associations with the current crew of their warship.
 * Bosun (Boatswain) - A starship's Bosuns are disciplinarians and taskmasters in a crew, assigned to oversee the common enlisted ratings and indentured workers, determine their duties and ensure that they are carried out efficiently. This often means that Bosuns are responsible for enforcing discipline on recalcitrant crewmembers, and are likely to handle that task personally. This makes them unpopular figures, and aboard many warships they find themselves naturally allied with a ship's Sergeant-At-Arms, as their duties are similar.
 * Crewboss -

Ratings
Ratings are the basic enlisted voidsmen aboard a warship that take care of the menial tasks; hauling shells and missiles, re-routing cables, clearing debris and conducting basic maintenance. Men and women in this class typically have a myriad of sub-classifications (ratings) that specify their role further, e.g. Gun-Layer Third Class, Fuse-Changer Second Class and so on. Ratings make up the great bulk of the starship's crew and will be the ones doing most of the fighting during boarding actions. Contrary to popular belief, many Imperial Navy Ratings are volunteers, for the pay is good and the conditions are better than those on many Imperial worlds. If there are not enough volunteers to fulfill a Captain's requirements he or she always has the right to send Press Gangs to tithe more crew directly from any planet along the way, which may include penal colonies or hab-blocks. In practice, this is often achieved through collusion with the local Planetary Governor, but an Imperial Navy Captain does not need civilian permission to take crew from any world.
 * Armsman - Armsmen are crewmembers trusted to carry weapons at all times on board the ship and maintain the contents of the weapons lockers. They keep discipline among the lower ranks and protect the crew as needed. Unlike most Ratings, Armsmen get to move around different decks of the warship in the course of their duties and their loyalties are carefully scrutinised. Armsmen are essentially the Imperial Navy's equivalent of marines in the most ancient sense of that term.
 * Trusted Crewman, Voidsman of Shipman (Archaic) - Voidsmen (also referred to by the more archaic "Shipmen" on some Imperial Navy vessels) are a warship's enlisted crewmen who possess some training and skill, and are the Ratings most likely to be entrusted with tasks such as conduit-maintenance, bulwark repairs, cog polishing, or other menial jobs that might require some skill and autonomy. Hive Worlders are favoured as Voidsmen due to their familiarity with advanced technology and the fact that they are inured to the worst of the noise and claustrophobic conditions found on Imperial warships.

Indentured Workers
Indentured or slave workers are those unfortunate individuals who rank even below enlisted personnel on a warship and are press-ganged from a world's slums or taken en masse from penal colonies for their ability to perform unskilled hard labour. They are given duties such as hauling guns into position, turning flywheels, and carrying supplies, heavy equipment, and Macrocannon shells. Most ships must replenish their crews of indentured workers every so often, as a steady stream die to malnutrition, accidents and disciplinary actions.

Attack Craft Ranks

 * Wing Commander -
 * Squadron Commander -
 * Wing Captain -

Specialist Ranks

 * Tech-Priest Majoris (Enginseer Prime) - The Tech-Priest Majoris is the Adeptus Mechanicus representative on a warship's bridge crew and is responsible for communicating the needs of the Mechanicus to the Captain and his officers.
 * Principle Navigator (Warp Guide) - The Principle Navigator is the senior-most Navigator on a warship who has the terrible responsibility of charting a passage through the Warp and bringing the starship through unharmed.
 * Chief Astropath - A Chief Astropath is the senior Astropath aboard a warship and has direct dealings with the Captain. He or she is responsible for ensuring that the warship's Astropathic Choirs are able to maintain adequate long-range communications.
 * Master Gunner - The Master Gunner is a high-ranking Warrant Officer given responsibility for the maintenance and performance of the warship's macrobatteries and Lances. He or she is also responsible for ammunition storage and power linkages.
 * Master of Ordnance - A Master of Ordnance is responsible for managing torpedoes and Attack Craft such as huge starbombers, lumbering assault boats and agile fighters carried within a warship's vast launch bays. The Master of Ordnance coordinates the efforts of the deck crews to ensure everything is fuelled, armed and ready to launch at a moment's notice.
 * Master of Arms - The Master of Arms, also called the Master-At-Arms, is charged with ensuring that all weaponry on board a warship is serviceable and ready for action, from the greatest macrocannon to the meanest Stub Pistol. The Sergeants-At-Arms report directly to the Master of Arms, and by extension all Armsmen are under his or her control, and so they also perform a role akin to that of a chief of police aboard ship. The Master of Arms is normally appointed from among the commissioned officers on a ship but more rarely a senior Warrant Officer may hold this position.
 * Ship's Surgeon - Also called the Chief Chirurgeon or unofficially, "Sawbones," the Ship's Surgeon is charged with administrating and maintaining the medicae facilities aboard the vessel. A Ship's Surgeon's duties include combating disease and malnutrition among the crew as well as suturing flesh and setting bones.
 * Officer of the Watch - The Officer of the Watch draws up duty rosters, assigns watches and attends the warship's chronometers. On most Imperial Navy starships the title of Officer of the Watch is rotated through the ranking commissioned officers. On older vessels it tends to become a permanent position assigned to the officer that has served the longest time aboard a vessel.
 * Fleet Commissar - Like their Imperial Guard counterparts, Commissars are appointed to the fleets of the Imperial Navy. Working closely with the ship's Master of Arms, the Fleet Commissar ensures a warship is kept battle-ready at all times and that the crew remains focused on their duty to the Emperor. A Fleet Commissar has the authority to declare a Captain or even an entire crew unfit for service if he or she is sufficiently concerned about their actions or the state of their ship. At least one Fleet Commissar will normally be aboard any capital ship. In the case of Escort squadrons a Fleet Commissar will divide his time between the different vessels in the squadron in a series of snap inspections and drills.
 * Ship's Confessor - A Ship's Confessor is a vessel's Ecclesiarchy representative who works tirelessly to promote the Imperial Creed among the crew and weed out potential Heretics. In these duties the Confessor is usually assigned by lay-preachers chosen from the most faithful on the lower decks. This is particularly essential on large warships as it allows the Confessor to concentrate his or her efforts on the warship's officers, shriving and chastising them as required, reminding them of their duties to the God-Emperor loudly and often.