Snorkel out
Ever since I attended the WC '98 in Sardinia I leave my snorkel behind before I dive. We enjoyed the company of Umberto Pelizzari during our training dives. There we learned to leave it behind, letting a dive buddy catch it up. If you don't go for depth it is not neccessary to spit out your snorkel although it would be useful to do it habitually, i.e. under all circumstances. Most of the reasons why have been said before. Therefore I summarize:
1. Safety: to clear Your snorkel implies a forceful exhale which may incur an unnneccessery samba/B.O. An unconscious diver may have convulsions that may lock up his jaws, which makes it very difficult to remove the snorkel and may hinder immediate re-animation. At least you should compromise and take your snorkel out for the last 10mt of your ascent.
2. Equalization: With a snorkel I am still able to do a BTV (my personalized version of free hand equalization, see a detailed description at my homepage) but I am not able to do the Fattah mouthfill technique, the only technique that helps me to do maximum dives. Note, that according to efattah's frenzel.doc it is still possible to pack with a snorkel in your mouth, but it's definitely harder.
3. Hydrodynamics: You definitely cut down water resistance if you don't have that thing dangling at the side of your mask. Makes sense.
4. How to abandon it? Murky and choppy waters may make it hard for a buddy to retrieve it and may distract him/her to spot you with undivided attention. So the best thing would be to attach it to a 0,5l soda bottle that is connected close to the mouthpiece of your snorkel at a distance of 25cm/10 inch. If it's longer, you may get intagled with the line and drag the whole thing down to the bottom. Looks funny to watch that
.
Even under hard conditions (wind, waves) I never had that thing drift away further than 10 metres during my dive. If the bottle has a bright color you'll always find it. This little system shouldn't encourage anybody to dive alone :naughty
@christoph: thanks for the good time we had together at the lake yesterday!
cheers
gerald