Tuesday, May 5, 2009

Lamp Oil, Torches, & Rations


Tonight, I decided to research just how long lamp oil burns.

Turns out that 1 pint of lamp oil burns for about 40 hours in an oil lamp (according to some survivalist groups that I found who actually burn this stuff on a regular basis). Also, oil weighs roughly 1 lb per pint. Actually, it weighs a bit less -- water is a pound per pint, so 1 pint of lamp oil weighs 0.786 lbs, according to Australia; but we're rounding, here. Let's figure that adventurer spill a bit of oil now and then, or their high-beam Adventurer Bullseye Lanterns burn a bit more than an oil lamp does, or medieval lamp oil was a bit less refined and energy packed than modern lamp oil.

1 pint = 1 lb = 40 hours
1 stone = ~15 lbs = 15 pints = ~600 hours = 25 days
1/3 stone = ~5 lbs = 5 pints = ~200 hours = 8.3 days
1/6 stone = ~2.5 lbs = 2.5 pints = ~100 hours = 4.16 days of continuous use

So, its reasonable to say that 1/6 of a stone of lamp oil (about 3 pints) might last for a week of dungeon exploration, assuming its not being burned 24/7.



A primitive light source researcher found that he could build a torch that lasted for 2 hours.


Close enough. I'd let it double as a club, because fire + hitting things... that's just cool.


Modern military MREs weigh about 12 meals/stone. They aren't the lightest field rations out there, but they have the benefit of modern technology; I'm guessing that hard tack and dried fruits and beef jerky probably were bulkier for the same calorie count. You can really get by on 1-2 MREs/day, so let's say that one stone of MREs gets you 6 days of chow.

Easy: 1 stone = 1 week of rations


That doesn't include water, which is much heavier. For survival you need 4-6 pints of water per day. If active, you need much more. So factoring in water, we get 6 pints (6 lbs) of water + 2.5 lbs of food = ~9 lbs/day.



That heavy duty rope you climbed in elementary school PE class (remember how embarrassing it was? I bet you do if you're reading this blog) weighs almost 1 lb per foot.

A modern climbing rope weighs 0.15 lb per foot.

A cheap manila rope that can hold 2380 lbs of weight (1/2" thick -- not that much when you remember that F=MA, so 200 lbs of person falling at 125 mph terminal velocity will have a lot of force!) is 0.075 lb per foot. A 1" thick rope is 0.27 lb per foot.

So, our notorious 50' of rope spool (adventuring essential) weighs in at 3.75 for the cheap manila, 7.5 lbs for the modern climbing rope, 13.5 lbs for the 1" manila, and 37.5 lbs for the old-school PE rope.

I think that if your adventurers expect climbing quality rope, it should be a STONE. In a dungeon, old school rope wouldn't hold up well. There'd be problems with rot, it'd be easily damaged from any sort of fall or sudden addition of weight (they didn't have dynamic ropes back then), it would generally kind of suck. So, making them check for degradation every time they use it is likely wise.

Silk rope would be superior rope that has an extra die or two for consumption purposes. I'd restrict super light weight "elvish rope" or somesuch (1/3 stone) to be a special, rare, perhaps even magical item. After all, even our modern nylon climbing rope weighs 1/2 a stone!



Heather said...

Hey, I made it to the top of that rope!

Unknown said...

Looks good; I saw this site with some useful info on Modern lamp. Hope it helps...

Vedron said...

Jessica, maybe I'm missing something, but that link is to a site for electric lamps.