Metric System for Old School D&D: Distance and Speed

Time to channel some of my Gamer ADD into actually making progress on one of my older series, in which I lay out a system to use the metric system in D&D. My reasons for doing this are multiple: my players' and my own convenience and ease, training people (especially students) to use the metric system, and how well kilograms work as a compromise in granularity between stones and pounds as a unit of weight for encumbrance.

Last time (quite a while ago), I covered weight and encumbrance; this time I'm going to cover distance and speed which, unless I'm forgetting anything, will mean that the only area left to cover after this post will be a catalog of items, including their weight in kilograms.

Wilderness distances are measured in kilometers (.621 miles). Six mile hexes can be converted into 12-kilometer hexes and the actual difference between 6 miles and 12 kilometers handwaved away. The distance from top to bottom is 12 kilometers, from corner to opposite corner is almost exactly 14 kilometers, the distance from the center of a hex to the midpoint of a side is exactly six kilometers and the distance from the center of a hex to a corner is almost exactly 7 kilometers.

The speed, in kilometers per day, of a character is calculated from the character's Base Movement Rate (discussed in the previous post on this topic). A character traveling at a "normal" pace will cover six time their BMR in kilometers in a day. This means that an unencumbered character (with BMR 4) will cover 24 kilometers in a day- almost 15 miles. If we go off the assumptions that a normal person will cover 12 miles a day at a "normal" pace, and that adventurers are in at least slightly better-than-average shape, this makes sense. It also means that an unencumbered party can cover about two hexes a day.

Characters can "forced march" and cover 12 times their BMR in kilometers a day, but their players must roll at or under their Constitution scores or they are fatigued at the end of the day. A fatigued character loses one hit point for each kilometer they travel at more than a leisurely "half" pace. Characters can recover from fatigue with a good night's sleep and a half-day's rest. An unencumbered character, then, would cover 48 kilometers- almost 30 miles- in a day if on a forced march. That's probably pretty generous, but, hey, this is D&D and I'm devising a simple system that works, not an exact simulation of overland travel.

During combat all distances are measured in meters. During outdoor combat, characters may move up to three times their BMR in meters in a combat round (one minute). During indoor combat, characters move up to their BMR in meters during a combat round.

Indoor distances are also measured in meters. A character moving at a careful pace, the only pace at which mapping is possible, may cover 10 times their BMR in meters during one turn. (A turn is ten rounds. A round is one minute, so a turn is ten minutes.) A character moving at a normal pace (perhaps in an already-mapped portion of a dungeon, or on the way out of a dungeon) may cover up to 20 times their BMR in meters during one turn. A character that is running may cover up to 40 times their BMR in meters during one turn.

An unencumbered character, then, would cover 40 meters in ten minutes at a careful pace, 80 meters in ten minutes at a normal pace and 160 meters in ten minutes while running. Keep in mind that this is all in an indoor- that is, dungeon- environment, so the running speed is for running through a poorly lit, irregularly leveled, cluttered and confusing environment, all with at least some dungeoneering gear, as opposed to running on a clear, open and level track with only runner's clothes to encumber. Perhaps "scrambling" would actually be a better term than "running."

What do you think? Is anything particularly out of whack?