well , thats just a stroke of genius if I ' ve ever seen one . <| sep |> Not all of them . Navigator Houses are a lot like the Houses in Game of ThronesA Song of Ice and Fire . There are big ones like Belisarius who receive the honour of Navigating the ships of Space Marine Chapters , Explorator vessels , Imperial Navy ships and the like . These enjoy great prestige and influence and are treated like royalty . But there are a lot of Houses and they ' re not all created equal . Whether through debts or scandals or interHouse rivalries or even just generating subpar Navigators some aren ' t allowed the privilege of Navigating for the big leagues . So they have to work with Rogue Traders and Merchant ships and other civilian vessels instead cause hey , someone has to do it . The Navigator in the NL books is exactly this . Something that draws her to their service is giving her the chance to Navigate an actual Astartes Strike Cruiser which she could never do for the Imperium . And with the added challenge of not using the Astronomicon she can feel real pride at her work .