This should be an interesting topic because every rescue class is not equal. I know this because there are far too many people advocating for knots on a throw rope in this thread. IMO, ropes are the last ditch effort.
Some manufacturers put a loop in the end and that is the first thing we remove. Some boaters clip into this loop to leave the ropes' end obvious and accessible. If the cinch cord at the top of the bag breaks or the rope decides to payout, you now have the possibility of a 50+ft rope entrapment in your boat. The bag can get caught on a number of things, so why create another snag point at the opposite end of the rope? Do you like to limbo while you swim?
I have taken a few different Rescue 3 SWT/WRT/AWRT/TRR over the past 15 years. One detail I have retained, a knot can and will get caught between rocks/trees where a clean rope won't. I have seen this happen to a "prestigious" outfitter in the top of Clavey Falls on the Tuolumne. Six customers swimming with a 75ft loop of rope in the water off a pinned boat. It is unfortunate they're so protective over the footage because it presents a valuable lesson on ropes with knots in water.
If you have enough time to clip two ropes together under tension, you should have noticed this and just set boat safety that could paddle/row to swimmers, pre-anchor the rope, or apply a girth, munter, clove hitch. Friction can do a lot; one foot of webbing or rope is enough to wrap around a leg or arm and entrap a body.
Of course... all of this depends on the situation.
Originally Posted by Roddy
I have been dragged into a river with a swimmer on the other end. A solid and secure standing platform and low center of gravity (i.e. Sitting if necessary) was my lesson from that.
Everyone needs to look into the friction coefficient of the human body in relation to the surface it's on. One person can pull and sustain an average of 75lbs with secure footing. Do you think secure footing is easily found on a riverbank and enough to hold a swimmer in current? Keep in mind, 1 cf of water = 7.48gal x 8.34lbs = 62.38lbs.
No offense, but if you got dragged into the river after throwing a rope, good. That's what happens with piss poor planning while also showing you're committed to your buddy. Now you know more than one person on a rope isn't just a good idea. What doesn't kill you...