I'm writing a campaign where I'd like the players to have a single ship from start to finish. If they start with a frigate (which is most likely), is there any way that ship can later become a light cruiser (or a light cruiser become a cruiser)?

I'm guessing it's unlikely, but I hate the idea of the character's trusted vessel being put aside just so they can buy something stronger later on.

Is there a way to have the hull actually be a light cruiser but so old and decrepit that the stats (and cost) are the same as a frigate? That way they could upgrade over time, eventually ending up with a light cruiser, without losing their initial ship,

I haven't been playing the game long but frigates look to be about the best a group can get for their cost. Bigger ships can eventually have more shields but the pieces tend to take up more space and use more power so not much is gained over all.

But, you could simply find a big ship that they would like using for a long, long time and then put really poor quality components in it and give it a few drawbacks. It'll take a bunch of acquisition tests and endeavours over quite some time to get the components up to high quality. Plus, the built in extra drawbacks could take even more of both of those to get rid of. In essence, they have a whole lot of potential but it'll take a massive amount of work to make it come to fruition.

Take note that your PCs don't have to get rid of their old ships.

In BFK there are rules for poor quality components. If you give them the final ship you want them to have and make sure all of the essential components and weapons are of poor quality, you can leave the rest of the ship empty (or full to more poor quality stuff!) and then it's a job to upgrade. The thought of a venerable old grand cruiser suffering the indiginity of Thunderstrike Macrocannons is making me chortle.

With the rules as they are in the books? No, you can't have a ship actually be a light cruiser, but start out as a frigate. They're entirely different hull types, with about 2-3 kilometres worth of ship difference between them.

As others said, you don't have to get rid of their old ships, but no, you can't upgrade frigates into cruisers.

Thanks for the help all. We put together the ship last night and it's mechanically a Falchion-class frigate but story-wise a beat-to-hell Endeavor-class light cruiser (the broadside gun areas are ruined so smaller guns have been mounted dorsally, half the crew quarters are open to the void, a lot of the interior room is unsusable due to damage, etc.). We're using the stat block and components as-is except for length/beam and tonnage. The hull repair (and subsequent component swapping) will be done at a year-long break in the storyline somewhere down the road.

My players brought their characters across from a Dark Heresy game and started with a very beat up cruiser. The component quality rules weren't out at that point but the guys they stole the ship off (long story) were basically using it as a mobile space station. It had drastically reduced power and space, huge amounts of damage and so on. I did a series of adventures, each of which would unlock a certain amount of power or space when complete.

e.g. a section of reactors had been sealed off by the tech priests many decades ago after a gellar field failure led to a possession of a reactor. This reactor complex now had a big lightning type daemon lurking there happily feeding off the reactors. So the ship was denied the power from those reactors and worse, couldn't even shut them down remotely so they still consumed fuel. The PCs went in, had a huge fight, lost more than a few armsmen, defeated the daemon (and made a legend out of an NPC armsman who consistently passed fear checks, attack and dodge rolls and generally excelled) and that allow the tech priests to re-sanctify the reactors, boosting the ships available power.

Ki_Ryn said:

Couldn't you just use the stats for the Endeavor-class, but just not have many facilities, weapons, etc, on it? The way you've done it doesn't really make much sense, in the way 40k ships work.

How are you going to explain weapon mounts moving around? Or the repaired ship being slower than the battered ship (because Frigates are, 90% of the time, faster than any type of cruiser)?

An Endeaver hull, even empty, cost more Ship Points than we rolled.

The hull has empty broadsides bays, with the power and fire control connections rerouted to new, temporary" dorsal mounts. I'd be ok with the light cruiser keeping dorsal mounts (instead of broadsides) if the players want to later on.

The repaired ship will be slower because of the mass increase when bays are filled in, several thousand cabins are repaired, and other components are replaced with more cumbersome versions.