Traveller Tuesday: Airlocks

Spring weather has relaly been playing merry with my sinuses lately, resulting in a LOT of sinus headaches that start mid-morning or early afternoon and progress until evening or later. Ugh, not fun at all.

I need to live in a pressurized space. With airlocks. 

My use of Traveller setting and dress falls under
fair use guidelines for both Mongoose and Far Future Enterprises.

In the core rulebook for Mongoose Traveller, no tonnage rules are given for airlocks. There's a single line about how "A ship has at least one airlock per 100 tons" on p137, but that's so vague as to be useless. 

On the whole, though, this doesn't matter because tonnage rules aren't given for lots of things in the core rules. For example, there's no displacement for landing gear, and yet we know that all ships have them. This falls into what I call gameable space: it's not exciting to allocate tonnage for landing gear, and we know all ships are going to have it, so we save the crunchy mechanics for things that not all ships will have, or will have in different volumes or amounts. 

Then High Guard came along, and with it rules for small craft construction, and we called this good... but now there were tonnage rules for air locks (1 dton each, cost 0.2 MCr.). Which made sense, because small craft are, well, small, and therefore less likely to have airlocks (fighters certainly don't need them). And having them/not having them now becomes a gameable space thing: there's lots of drama to be had if, for example. your shuttle crashes on an airless world miles from the spaceport and there's no way to go outside and make repairs without depressurizing the whole ship. 

Except now there's a problem:  Once a thing in Traveller costs tonnage, it always costs tonnage, and the gearheads will remember it and implement it. And so I started to see ships paying tonnage for airlocks when they previously did not. Worse, I only saw it some of the time; the most glaring oddity is how the 3,000 dton Agashaam-class Destroyer in Fighting Ships pays for a single airlock when a) it clear has two of them and b) none of the other ships in that book do. 

All of which is a very longwinded leadup to this very short and simple house rule: For every 100 dtons a ship has, it gets one airlock for free. Others can be added but they must be paid for. 

I think this works marvelously well: 100 dton ships rarely need more than one airlock due to small crew size and lack of cargo capacity. As size increases, so do cargo/passenger/crew requirements, and so additional airlocks become necessary. 

Two notes to help flesh this out:

1. The dtonnage is not for the lock itself; it's for the pumping equipment and other life-support gear that enables the lock to quickly pressurize/depressurize.  Because honestly, given enough time and access to life support controls, any space between bulkheads can become an airlock. 
2. This supports the (quite logical) deckplan assertion that places personnel airlocks next to cargo locks. That way the cargo locks cycle faster by using the same dedicated pumping equipment.