What do You Mean it isn't Just a Liner: Armed Merchant Cruisers

By Source, Fair use, 

I recently re-read David Weber's Honor Harrington up to Honor Among Enemies, and I thought the idea of and use of Armed Merchant Cruisers in the Official Traveller Universe. Armed Merchant Cruisers are a type of auxiliary warship, converted from merchant ships. Generally, they would be equipped with older weapons, and feature limited fire control with no armor.

These ships come about because of commerce raiding as both the wolves and the sheepdogs around helpless merchants. The predatory ones, like the German Auxiliary Cruisers such as Von Luckner's SMS Seeadler. These ships operate under false flags, which are theoretically replaced with the real one to give the victim a chance to surrender. The other reason, like the ill-fated HMS Jervis Bay, are built to be readily available escorts and protection. Q-ships were a subset of these, smaller ships equipped to trap commerce raiders, submarines usually, with a hidden armament.

Thus, an Armed Merchant Cruiser exists because purpose built warships are for some reason unable to complete either commerce raiding or commerce protection and patrol duties. In some cases, you could find a peace time force of such auxiliary ships, especially in Navies looking to ensure a knowledge continuity in unusual craft, or as aggressors. A Naval Depot could include a few as part of it's defense and exercise force, or as part of a Convoy operations school that can be re-tasked in a time of war.

There is a couple of official designs for a Q-ship, also useful as an Armed Merchant Cruiser. First, in SJ Games Deckplan 3: Empress Marava-Class Far Trader, there's the Empress Arbellatara class variant, that replaces the cargo space with Rampart fighters. Another is provided on page 71 of Mongoose Publishing's Traders and Gunboats, based on the Type R "Fat Trader". These are both common enough designs a competent referee could set them on the players as a joker if the PC's have become a bit too ethically challenged. More may be in other books I do not own.

An Open Armed Merchant Cruiser would be operating as a Navy unit in all respects, squawking a Navy Transponder code, and operating as a normal patrol ship or as the escort for a convoy. In some ways, a converted merchant hull would make sense, as it would have similar performance to the ships it is escorting. On patrol operations, it could be set up for a longer duration operation (in-system performance).

The piratical LCDR Tom Dodge in "Down Periscope"

A Hidden Armed Merchant Cruiser would be looking more like a scruffy tramp or fat trader, and suckering in unsuspecting prey of a variety of sources. It wouldn't act Navy in any fashion, until it's too late for it's enemy to escape. In many ways, it's a completely legal pirate. It's a sucker punch like a System Defense Boat wing in the gas giant killing fuel skimmers.

Of course, these could be working together, where an open Armed Merchant Cruiser is 'escorting' a convoy of hidden ones, Most commerce raiders might consider turning tail when the entire convoy starts spitting nukes, and a large group of fighters are being launched.

In my view of the Official Traveller Universe, the Imperium is big and powerful, but just can't be everywhere. In many cases, local Dukes are unable to get the effective ships commerce protection, even in peace time, from the Imperial Navy, or else a world finds its commerce is under attack, and need mildly combatant starship of its own to ensure fewer merchants are lost. As I see it, the Imperium is more willing to give them Armed Merchant Cruisers than 'real warships', as they are not as emphatically Navy as a Patrol Cruiser, or a Destroyer. In some cases, along the lines of various other vessels navies have in war time, but prefer to get rid of as they are not part of the 'proper fleet' and offer opportunities for junior officers to show up their seniors. The subsectors and systems near the Vargr Extents (Coreward frontier of the Imperium) will have Armed Merchant Cruisers on their permanent Navy Lists, while those on the interior will normally see few if any.

Navies might not be the only operators of Armed Merchant Cruisers. A shipping line of type R's or A2's may buy an Armed Merchant Cruiser based on their fleet hull, as a way to ensure their cargoes get through. An mercenary Armed Merchant Cruiser could operate beyond the Imperium, supporting various small states against both pirates and rival small powers, particularly in the Extents.

In a campaign, an Armed Merchant Cruiser would be a different way to run a war, and to keep it at the players scale. A group of middle aged spacers looking to get out of a boring retirement would be a very skilled crew for one. Former Navy and Scouts would be the crew, boarding parties for Marine and Army characters, a Merchant type would add believably to the ruse of being a trader. Reformed pirate types would be useful as well; for understanding the piratical mindset better than some stuffy Navy type. Encounters would help the referee determine the course of the war. Successes help move the front along, but failures lead to losing the war. It can also be a mechanism to draft the party into the Navy, "Since you have been successful in this, we're promoting you, and sending you to a new cruiser," could be the response they get from success. It helps keep it at the Adventure Class ships level, where it's all smaller ships, and the PC's make the important decisions. The fleet units are escorting the Megafreighters, while the small Armed Merchant Cruisers are stuck herding cats forming Free Traders into a convoy.