The VESL straight leash will work on any board and is a great way to keep you safely attached to your board. The coiled cord keeps it out of your way and out of the water while paddling flat or textured waters. Due to the coiled section this leash is not recommended for paddle surfing.
For touring and racing, a coiled leash keeps it out of the water and minimizes drag and keeps it close so you can quickly rejoin the race. A coiled leash is also great for general flat water paddling as it stops a lot of tangles around your feet and other items.
ALWAYS WEAR A LEASH, IT WILL SAVE YOUR LIFE.
For a SUP paddler of any level, on any body of water, it can quite literally mean the difference between life or death…
One of the worst things that can happen to you on the water is to become separated from your board. Not only is your board a PFD, it's also an anti-hypothermia device that can keep you afloat and far more visible than if your in the water bobbing. The temptation for some paddlers may be to look at a calm lake and say "I don't need a leash here" but the fact of the matter is you should use them everywhere and all the time.
If you fall in and there is wind, current or even a breeze on a lake, river or in the ocean, your board will catch the wind and literally sail away from you. Chasing your board, especially with a paddle in your hand, is a recipe for exhaustion.
Best bet in the event of leash failure (or if you see a paddler struggling to swim while holding a paddle) is to tell them to ditch the paddle and swim to the closest board (yours or their own) or (swim/float) to safety. Paddles are designed to float and can be retrieved once a paddler is safely back on their board.