Sounds like a good idea to throw the halyard overboard to straighten it out, but with 20m of rope trailing behind you another problem can occur : Another boat could run over the halyard & get tangled, this happened a few weeks ago at a big regatta with keelboats, dinghies & cats - about 400 boats on the water. A Peterson 33 (about 4 tons) ran over the trailing halyard of an Inter-20 & got it wrapped in the rudder-pin (Guess who won that altercation ?) The Peterson carried on straight, the I-20 slowed down quickly, stopped dead, and then charged off backwards with the spinn. still up ! This presented a new problem, since the I-20 skipper couldn`t drop the spinn with 4 tons of keelboat on the end of the halyard. Luckily he had a hook-knife - cost him a new halyard. Unfortunately he had no rights would there have been a protest - his halyard was not in it`s normal sailing position at the time of the incident. Luckily both parties saw the humor to it & there was no protest, just a friendly exchange of words. I`d love to have seen the I-20 skipper`s face doing 6 knots backward with the chute up, though !
If you fit a snuffer, the halyard is a continous line to the spinn. patches & doubles up as a retrieve line - it will seldom get knotted since there is very little slack in it if you get the length right.