On 28Jun2020 1525, Thomas Jones-Low wrote: > > The other thing to keep in mind is developing the Jump Drive is a > difficult challenge. It’s only been done seven times in in the history > of Charted Space. Based on the outcomes of the misjumps and a few > other statements, the process of entering jump space is an unstable, > chaotic one. You, the Astrogator and the computer system you are using > need to know a number of factors to a high degree accuracy. The jump drive, as it was originally described, was a quite reliable piece of kit. You could only misjump using the original '77 rules if you jumped too close to a world or star (and the star part is explicit), were using unrefined fuel, or your drive was past due for maintenance. The chance was 12+, -1 if using refined fuel (i.e. no chance at all) if you did things right. The '81 version changes things somewhat - using unrefined fuel is perfectly safe in a scout of military ship, stars are no longer mentioned as causing problems, there's an extra DM for being within 10 diameters of a world (in case within 100 diameters wasn't scary enough), lack of drive maintenence doesn't make misjumps more likely, and a bad enough roll can destroy a ship rather than just cause a misjump. In both versions, given the size of the computers required for jumps, especially long ones, it seems that finding a 'course' that gets you where you want to go is hard, but without it it seems that actually you just go nowhere. In MegaTraveller there are a series of tasks required before you can jump, but the same rules applies - if you play it safe there's no chance of a misjump. In TNE the same applies, but there's also a Piloting roll upon emergence, and a poor roll on that means emerging with an inconvenient vector. T4, I'm not sure of the way it's expressed, but I think it's like the original '77 rules, but without the bonus for refined fuel. If so, this is the first set of rules that gives a chance of a misjump when you're doing everything right. GURPS Traveller allows a small chance of something going wrong on a jump even if you play it safe, and there's some chance this will be a misjump, but they should be very rare unless the ship's engineer has a low skill level. T20 is less than clear (I assume the DC21 check for misjump is a typo, because otherwise it's automatic), but seems to imply that with a low-skill astrogator it'll be fairly common, but most misjumps just damage machinery or mess with the occupants - about 1in20 are 'go who knows where' events, and 1in10 are 'game over'. MgT requires an engineering check, modified for bad fuel, etc., which means that a skill engineer can safely jump when common wisdom says you really shouldn't (something that's also a thing in MT, TNE, and GT). I don't know T5 well enough to be sure of the odds of misjumps, and don't have access to other Hero Traveller. Overall, the newer the rule system, the worse your odds, it seems. -- Rupert Boleyn <xxxxxx@gmail.com>
