What size of rope makes sense? A discussion.
Posted: Sun Nov 14, 2021 10:33 pm
So I recently posted somewhat jokingly about the discrepancy between Dungeons and Dragons hempen rope weight (10lbs for 50 feet) and the weight of my trusty hemp rope (1lb for 57 feet).
Based on crossectional area of my rope, pi, and the square-cube law, rope that would weigh as much as Dungeons and Dragons thinks it should would be an inch and a quarter thick! This is available to purchase, and claims a breaking strength of almost 6000lbs!
...Which, when you think about it, is about the strength of modern climbing rope. So...is Dungeons and Dragons more accurate than it seems? Should I upgrade to some 5ft/lb ship-mooring rope?
No.
The reason is several fold. First, because I don't take rope into the wilderness for climbing, whether using modern or pseudohistorical gear. Honestly, I would probably do quite as well with rope half this diameter.
Second, because those who did take rope into the wilderness for climbing prior to the invention of modern materials...still used rope of about the same diameter as mine. According to this source (which has some badass photos of women rock climbing in full-length skirts and bonnets), people who used ropes for rock climbing have pretty much always used rope in the 8-11mm diameter range. However, they used it quite differently; the idea of being caught by a rope after a fall was ludicrous, in part because of the rope's lower strength, but perhaps even more due to its lower elasticity. Having your pelvis jerk to an instant halt after a 10-foot drop while the rest of you tries to keep going is not good for one's back.
Manila rope has slightly greater elasticity, but for our purposes, Tolkien talks about "hemp". This could be a colloquial usage, referring to any kind of fiber, but for my part, I use real hemp rope, which has virtually no give and is therefore wildly unsuitable for climbing, by modern standards.
Still, it's interesting to know that someone like Sam, using a rope to descend a rocky defile, would likely have used something far closer to what I've got than a big crossfit rope.
Based on crossectional area of my rope, pi, and the square-cube law, rope that would weigh as much as Dungeons and Dragons thinks it should would be an inch and a quarter thick! This is available to purchase, and claims a breaking strength of almost 6000lbs!
...Which, when you think about it, is about the strength of modern climbing rope. So...is Dungeons and Dragons more accurate than it seems? Should I upgrade to some 5ft/lb ship-mooring rope?
No.
The reason is several fold. First, because I don't take rope into the wilderness for climbing, whether using modern or pseudohistorical gear. Honestly, I would probably do quite as well with rope half this diameter.
Second, because those who did take rope into the wilderness for climbing prior to the invention of modern materials...still used rope of about the same diameter as mine. According to this source (which has some badass photos of women rock climbing in full-length skirts and bonnets), people who used ropes for rock climbing have pretty much always used rope in the 8-11mm diameter range. However, they used it quite differently; the idea of being caught by a rope after a fall was ludicrous, in part because of the rope's lower strength, but perhaps even more due to its lower elasticity. Having your pelvis jerk to an instant halt after a 10-foot drop while the rest of you tries to keep going is not good for one's back.
Manila rope has slightly greater elasticity, but for our purposes, Tolkien talks about "hemp". This could be a colloquial usage, referring to any kind of fiber, but for my part, I use real hemp rope, which has virtually no give and is therefore wildly unsuitable for climbing, by modern standards.
Still, it's interesting to know that someone like Sam, using a rope to descend a rocky defile, would likely have used something far closer to what I've got than a big crossfit rope.