But I see that a loop would have worked even better, I could have just pulled the line back on board. I like it!
Exactly. That's warping as I understand it. I would make one suggestion, however: Use a polypropylene line as a warping line for the following reasons: a) it's stretchy and can take a shock load, which is useful coming off a dock that may be in motion in the oppositie direction of a boat under power; b) it's cheap enough that if you lose it or break it, it's no big deal; c) it floats
, meaning that if you drop the loop or back over it, you might avoid fouling the prop, a situation I wouldn't wish on anyone who is in conditions requiring a warp in the first place.
On my boat with hank-on foresails, I used to have a No. 3 or equally modest genoa rigged ready to haul up in such conditions in case I had an engine failure or a fouled prop. Before I determined that a busted waterlift was hurting my engine, causing it to overheat and/or stall, I had to occasionally sail back into my dock, and the availability of at least one working sail to provide thrust saved me from unpleasantness on more than one occasion.
Since I fixed the problem, my engine on the old boat is very reliable and hasn't failed me once, but the cautionary instinct is still strong, and I usually have the sail cover off, the sail ties off or loosened and the main halyard rigged and ready to rise before I leave the dock on the new boat...just in case!
I recommend to everyone that they try all their usual maneuvers under sail alone (with the engine on in neutral). It is exceptionally good practice, very seamanlike, and you may like the effect it has on fellow yachties when you pick up a moor under sail alone.