Would never leave port without it !
For smaller vessels I agree that one can question the need for a third reef, at least when sailing reasonably well protected waters.As soon as you sail unprotected waters, whether coastal or offshore, there is one overriding reason for a third reef. This is the fact that sooner or later every sailor is going to be in the dreaded situation of having to claw off a lee shore, reef or bank while being caught in a bad blow. In the age of the square-riggers that threat would lay like a cold blanket on a sailor's heart because of poor upwind ability. The point I am trying to make is that as soon as you douse the main and proceed to sail on the jib alone your upwind ability is likely to be not a whole lot better than that of the square riggers of yore......On the other hand if, in a HARD blow, close-hauling a double-reefed main still causes too much heel and sideslip to clear that looming headland, whereas slacking off the vang or mainsheet and spilling the wind makes you loose too much drive against those big coastal waves, your third reef might just be the ticket. If well designed and put in properly it is amazing how nice a blade even a tired old sail can make (since the top part has stretched least). In combination with the right working jib you might yet make it around that headland and enjoy the rest of the season!Have fun,Flying Dutchman