Traditional watch systems, including the "Modified Swedish" are good, but can leave a crew very tired, as off-watch times may shift all over the day and night. This can dramatically disturb sleep cycles.
After the 2000 and 2002 Pacific Cup, many members of our crew, particularly including yours truly, slept for 17 hours straight after hitting land. I set about to develop a watch system that kept wake/sleep cycles as constant as possible while still giving everybody a break from the dreaded 2 am watch.
Pacific Cup Offshore Academy - March 2012 - Liz Baylis and Todd Hedin