Re: Towing a disabled boat in water.
Nylon will come back extremely quickly when used in marine applications. I've seen tubes flip over and fill with water, snapping the nylon tow rope instantly. The driver was sitting on the seat back, and it took a couple weeks for the whip mark to go away! I've personally sent waterski handles OVER the boat from holding on too long after a bad fall.
Ask any wakeboarder or slalom skier. Nylon is a rubber band. You need spectra ropes for zero stretch.
I'm guessing you are probably thinking of spectra or dyneema ropes. Nylon is never used for a winch. (nylon is dirt cheap, spectra/dyneema and its cousins are fairly expensive)
You are right, though I don't know of spectra or dyneema, I am thinking of synthetics, and not nylon.
However, my statement (with nylon replaced with "synthetic tow rope" or something to that effect) remains true.
Proper synthetic pull ropes do not hold potential energy the way a steel cable does.
Use the right stuff, and use the jacket on the line trick just in case.
And to the point about stopping and helping.
If I can, I do. Though I openly carry a gun on my hip (legal in my state, don't know about yours) and am a very friendly person.
People who are out to do harm generally think twice about hurting the armed citizen.
Disclaimer: This was only mentioned because it is somewhat on topic for the thread in my opinion, and the open carry is merely the reason I feel safe helping strangers. I am not here to debate whether gun ownership, carry, etc is right or wrong. This would be very off topic for this forum and I will not answer any posts intended to start such a discussion. There are other more appropriate forums for such a debate and can be found through a quick google search using the search terms, Open carry.