Help me, dear hive mind, with a question that has plagued me for too long, given its (apparent) simplicity and obvious answer.
If I blow into a sail, will it move my boat forward, even if imperceptibly? Will it produce a net-plus forward movement into the desired direction? Or is there a type of “recoil” that is caused by the air exiting my mouth that will compensate for that net forward movement, pushing me and thus the boat back again? Feel free to apply this to a “pure” environment that assumes no pesky friction or other disturbing factors, as well as to a more realistic environment.