Select to expand quote
Basher said..
If you break a fin when sailing along you can get usually back to the beach by attaching your harness to the back of the board. This then adds enough drag at the board tail, to give it 'directionality'. And you can then use your sail to move inefficiently but in a way that gets you back to a downwind beach. You probably won't plane, and you can't get upwind like this.
Another good reason to sail up wind of your starting spot. I had to do the harness thing a few years ago and it's f***ing hard work, specially if you need to go any sort of distance. For one thing, you don't have a harness

.
I've wondered sometimes if sailing alone and/or any distance from shore about carrying a small spare fin and a short screw driver. Never done it tho