You’re out on the water and a line breaks. Inhaul, outhaul, downhaul, uphaul, harness line…something you need snaps. You’ll be happier if you’re carrying a piece or two of downhaul line to put yourself back together. In twenty years of windsurfing this has only happened to me once (I’m fanatical about checking and replacing worn line) but the time it did I was two miles from the launch and my harness line tore off. Yes I could have flipped the boom (that’s fun to do in deep water) but instead I pulled out a piece of line, tied it on, and had an improvised harness line that worked just fine to get me back home.
When I bought a new harness recently I didn’t make a point of stashing emergency line on it (I usually have two downhauls taped behind the bar). But after Christian’s adventure at sea a few months ago I made a point of correcting that situation (as did Christian). He and I opt for behind the bar storage, but you can also stash line in the back pocket of your harness if you have one (I don’t want to take my harness off if I don’t have to) or put a piece in the luff sleeve pocket of every one of your sails (requires sails with pockets, and line in each sail).
Do this. And while you’re at it, replace all your downhaul lines for cold weather sailing (now is not the season you want to use your emergency lines). Cut off the worn portion of your downhauls and make them your new outhauls. Check boom inhauls (how often do you do that?) For super stud status, replace your lines with Formuline if you haven’t already, and glory in easier downhauling and longer line life.
(Looks a little silly, works great. My purple tape and Christian's blue line both call more attention to the set up than perhaps is necessary. I'm going to switch to electrical tape in the name of fashion! Note the orange bit on my rig...that's a safety whistle...less than $5 at Amazon. Photo by Jeff.)