Ship's Officer
Where Voidmen are the heart and muscle of a voidship, the ship's officers are her brains. From the Lord-Captain to the Boatswain and Purser, these men and women are responsible for the health and welfare of their ship as well as the men and women in their crew. There are two classes of ship's officer, commissioned and warrant officers, and each is lord and master over their area of the ship.
Commissioned Officers
Commissioned officers are typically higher bred men and women from noble or politically connected families within the Imperium. These officers wield enormous power aboard their ships, and shoulder the largest responsibility. Their influence extends to the entire ship, and their orders are to be followed immediately and without question.
Lord-Captain
An Imperial Navy rank adopted by most Rogue Traders and Free Captains, Lord-Captains command Warp capable voidships of frigate size and larger. The God-Emperor may be lord and master of all mankind, but aboard his ship a Lord-Captain's very word is His law. Lord-Captain's tend to be aloof, uncompromising figures unbowed by the awesome responsibility entrusted to them, at least publicly. Whether a tyrant, martinet, swashbuckler, strategist or saint, a Lord-Captain is always an exceptional individual.
Commander
Another Imperial Navy rank adopted by aspirational Free Captains and Rogue Traders, Commanders typically command the smallest Warp capable voidships such as Cobra-class destroyers and Star Clippers. Like Lord-Captains, they are the ultimate power aboard their ships, and are addressed as "Captain" when in command of a ship.
Lieutenant
Lieutenants serve in a number of subordinate leadership positions aboard a ship. Depending on their size, Warp capable voidships will have anywhere from five to fifteen lieutenants. The five senior most lieutenants aboard will be rated First through Fifth, with the First Lieutenant serving as the Commander or Lord-Captain's second and the Executive Officer or First Mate of the ship. Junior Lieutenants, from sixth to fifteenth, are called Sub-Lieutenants, and they are rated First through Tenth (First Sub-Lieutenant, Fifth Sub-Lieutenant, etc.). Lieutenants also command small, non-Warp capable ships like intersystem patrol craft or tradeships.
Midshipman
The junior most commissioned officers aboard any ship, these "Young Gentlemen/Gentlewomen" are essentially officers in training. Their lot aboard ship is to learn voidmanship and officering by leading divisions of Voidmen and attending lessons given by the Captain, Chaplain, and Tech-Priest Majoris such as astrography, navigation, and Imperial/Company/Dynasty doctrine. The number of midshipmen aboard a ship varies greatly, and they are often seen as a nuisance both by the officers tasked with training them and by the Voidmen under their nascent command.
Warrant Officers
Warrant officers are of lower birth or station than commissioned officers, and carry a warrant from the Imperial Navy or their respective company or Trade Dynasty. These officers are responsible for specific aspects of the ship's operation, medical facilities and gunnery for example, but have little say in the larger scheme of things. While of lower class and lower pay, their warrant entitles them to larger, private cabins, unquestioning loyalty from the crew (in theory), and a place in the Officer's Ward Room.
Boatswain
Boatswains (pronounced BOW-sun) of the Imperial Navy, and of those private and merchant navies modeled after that august institution, are the heads of a ship's Deck Department. They wield substantial power and responsibility aboard a ship, and carry a piercing whistle and sanctioned vox-caster as symbols of their office. Ships have only one Boatswain embarked, no matter the size of the crew.
Purser
A ship's Purser is the Warrant Officer in charge of the ship's administration, finances, and supply. They track all income and spending, dole out pay to the Voidmen, oversee refittings and overhauls, and keep the ship supplied with everything from uniforms to foodstuffs.
Chaplain
Chaplains see to the spiritual well-being of a ship's complement through constant prayer and preaching. Their responsibilities include recruiting lay-preachers from among the crew, teaching the Midshipman proper ecclesiarchacal doctrine, monitoring the faith and orthodoxy of the officers, and spreading the Good News of the God-Emperor among the heathens and heretics of the galaxy. Ship's Chaplains often lead boarding parties, and are among the most martial, rigid, and dogmatic of the ship's complement.
Void Master
Void Masters are crack realspace navigators and ship pilots. They work closely with their Captains to plot courses and chart unknown systems. Void Masters are the highest ranking of the Warrant Officers, and are roughly equivalent to Lieutenants. Indeed many Void Masters serve as Executive Officers on ships without qualified Lieutenants.
Ship's Chiurgeon
The Ship's Chiurgeon is responsible for the physical health and wellbeing of all officers and crew aboard his ship. Chiurgeons combat disease and malnutrition among the crew, set bones, amputate damaged limbs, and perform all manner of delicate surgery. Many Chiurgeons have little more than basic medicae training, a warrant from the admiralty, company, or Trade Dynasty, and a second-hand saw as their qualifications. Some, however, are full-on physicians with years of specialist medical training and degrees from the most prestigious institutions, and a rare few are members of the secretive Magos Biologis. Whatever their qualifications, they are usually a great comfort to the officers and crew under their care.