Deck shoes or non-slip, non-marking trainers. If you are sailing in cooler/wetter climates then yachting wellies will make a huge difference to your happiness and safety.
Maximus Leads Transatlantic Challenge (AP via Yahoo! News) The New Zealand super-maxi yacht Maximus took the lead in the Rolex Transatlantic Challenge when the schooner Mari-Cha IV had to stop for 12 hours to repair damage to one of its two masts.