I strongly recommend stroboscop flashlight for every person. Standrd flash attached to life jacket is visible from no more than 2 miles. stroboscop flashlight is visible from 10 miles! And one epirb (can be personal working on 121,5 MHz, or better 406 kind working on 121,5 and 406 MHz). This small thing is not very expensive now, and you can buy secon-hand.
RIB x-ing of Atlantic on Southern Route 1998;
FIRST RIB SOLO CAPE HORN CIRCUMNAVIGATION 2008
If You are not living on the edge, You are taking too much space...