physics, simplified but should work in the proper direction for the most part. indirect control - instead of controlling the boat directly, you control the sail and the rudder which exert forces on the hull.
left/right: rudder left/right space: raise/lower the sail up/down: sail raised: loosen/tighten the sheet sail lowered: row forward/backwards
Updates: 191116 Turn rate improved 191026 Hit the boat a few times with something harder than hand to destroy it and reclaim some material. 191022 Smash the boat with some dye to color the sail.