Expanded hiking rules

The hiking rules, as written in the core books, do not tell the complete story. They gloss over the details, and give you a simple answer which is correct for all completely normal situations, and rather wrong for any unusual situations. With some help from Kromm and the Steve Jackson Games Forums crowd (from the Hiking thread ), I reverse engineered the numbers for more detailed hiking. This is not a house rule per se, so it basically has the same problems as the official rules, as explained in Hiking Reality Check. See the next sections of this page for optional and alternate rules.

Your basic hiking Move is equal to your Basic Move x0.4 (modified normally for encumbrance). While moving at this rate, you lose FP equal to (encumbrance level +1).

Note from a reader (Gollum): The hint given by Dr Kromm (a day of walk is 12.5 hours of walk) gives a walking speed of move x 0.8 mph, not move x 0.4.

Hiking and encumbrance

In a normal situation (as described in the Basic Set), you have 14 hours to hike. Only 12.5 are spent actually hiking, with 1.5 recovering from fatigue (whenever you have taken 3 FP, you rest 30 minutes to recover them). This is as explained in this post from Kromm . Assuming no encumbrance, the end result is that, with a Basic Move of 5, you move at 2 yards/second for 12.5 hours, or about 50 miles. If you apply encumbrance modifiers (x10, x7, x4, x2, x1), you get the following:

Light encumbrance: You are moving 80% as quickly, and fatiguing twice as fast. The 1.5 hours you spent resting at no encumbrance is doubled to 3 hours, dropping your useful day from 12.5 hours to 11 hours. Combined with the slower Move, you only travel 35 miles (Move x7).
Medium encumbrance: 60% Move, FP costs x3 (useful day is 9.5 hours). You only travel 22 miles (round to 20, Move x4).
Heavy encumbrance: 40% Move, FP costs x4 (useful day is 8 hours). You only travel 13 miles (round to 10, Move x2).
Extra-heavy encumbrance: 20% Move, FP costs x5 (useful day is 6.5 hours). You only travel 5 miles (Move x1).

These numbers might seem high to most people, but this is explained in this other Kromm post (basically, an average character in GURPS is an average hero, not an average person, so the numbers are a little higher than in reality).

Physical fitness

What happens if you have Breath Control? Or if you are Very Fit (or Unfit)? What if you only have six hours to get where you are going? Would you rest, or push and arrive at -6 FP?

distance = hiking Move x2 mph, reduced -10% per FP/hour

The following modifications are possible:

Hiking skill: allows you to improve your daily distance by maximizing little things: eating on the move, alternating speeds slightly to minimize fatigue, and so on. A successful roll improves your Hiking Move by +20%.
Breath Control skill: vastly reduces the time spent resting. For each FP lost, make a Breath Control roll. A success changes the -10% distance to a -2% distance. Alternately, you can roll once per hour, and each point of success is counted as one success.
Fit advantage: halves the 10% penalty for the effective FP/Hour, and the Very Fit advantage quarters it. This stacks with the Breath Control skill, so a good Breath Control skill combined with Very Fit would allow you to march with Heavy Encumbrance with only a 1% reduction in distance.

Other options can be considered:

Interrupted Hiking: If you encounter something during the hike, roll 1d/2 (round down). This is how many FP you are down at the moment (the basic hiking system is to walk until you've lost 3 FP, then rest for 30 minutes).
Forced March: Instead of the usual hiking system, you can hike until you collapse (or until some set number of FP are lost). In this case, don't reduce your distance by 10% per FP! However, each hour costs you the FP normally.

Example: Henry Hiker has 12 FP, Move 5, the Fit advantage, and is at Light encumbrance. He decides to do a forced march until he is at 4 FP. It will cost him 1 FP per hour (due to the Fit advantage), and his Hiking Move is 1.6, or 3.2 mph. He hikes for 8 hours and travels 25.6 miles, and then collapses, exhausted.

Example: You can also combine these. Henry Hiker could hike normally for 6 hours of the 14 hour day (travelling 17.4 miles) and then forced march for the next 8 hours (travelling 25.6 miles) for a total of 43 miles... slightly further than he would have gotten without forced marching. If Henry Hiker had no encumbrance at all, he could have forced marched the whole day (14 hours) at Move 2, for a total distance of 56 miles (and he wouldn't have been completely exhausted at the end, with 6 FP left).

Optional rules

To Do some people find the previous results really optimistic. According to Hiking Reality Check the problem is mostly because of the length of the basic hiking day, which is 14 hours. Here we should try to come up with some rules that model the fact that such long days of hiking can't be repeated for several days by average characters without them being more and more fatigued, up to the point that they can't hike anymore...

Longterm Fatigue

This house rule has been suggested in a few places, but the essence of it is this: for every n FP you lose and recover in a single day, you take 1 longterm FP damage. Longterm FP damage is treated like starvation fatigue, in that you recover 3 FP per full day of rest and meals.

The exact value of n can be debated, but 3 seems to work reasonably well. For hiking, this means that 5 hours of non-stop hiking will cost you 1 longterm FP. If you assume that you rest of 30 minutes every 3 hours, then a 6 hour hike will cost you 1 longterm FP (and you will be able to afford quite a few days of that pace before needing to take a day or two off for rest.

A 14 hour hike, on the other hand, with 12.5 hours worth of fatigue loss, will cost 4 longterm FP per day, and a mere two days of it will have you dragging or collapsing.

The problem with this house rule is that there are a lot of things which cost fatigue in a campaign (particularly a campaign with magic), and this will greatly reduce the amount of these things that P Cs can afford to do.