Here is a list of items that everyone should have with them while sailing and some of these are required by law to have on your boat anyway.
Hat, sunglasses, loose fitting clothes or clothes that can stretch with your movements, deck shoes with sipped soles, water shoes, whistle, sailing gloves, plenty of water, sun screen spf 30 or higher, change of clothes, towel, Coast Guard Approved Type III PFD, duffle bag, watch, and a rigging knife are just the basic items that you should have with you every time you go sailing.