Hey, I'm hopefully gonna write a longer post covering a broader amount of sports soon. I'm a narcoleptic/cataplectic paddle boarder.
I'm lucky enough to have cataplectic episodes that only last 1-10 seconds.
That said I've had 2 so far paddle boarding. As well as a narcoleptic attack.
Some of this may be obvious, but I'm trying to list all my tricks anyway.
-If you feel an attack or possible attack coming on. HIT THE DECK!!! Practice on land if you have to, then a few times on the water. Be able to go from standing to lying down in a split second on purpose. Hopefully you'll be faster than the time it takes for you to buckle on accident. I lay on my stomach with my right shoulder and right leg pinning my paddle underneath me. Putting the paddle between me and the board, so I don't loose it in the process. If you can, punch your arms forward through the cargo netting for good measure (especially paddling somewhere sketchy like a river that can knock you off the board even lying down.) Practice HITTING THE DECK every time when you first get on the water 2-5 times, till you feel comfortable.
-Life jacket. I know it doesn't look as cool, but neither does drowning. Your friends will respect you for doing ANY sport with a disorder they could never understand. I haven't seen one in person, but I believe someone makes a CO2 Cartridge one that only inflates when submerged at -2 meters.
-Helmet. Same reasoning as the life jacket. You can concuss yourself on water, but the helmet is useful for the shallows, and rocky areas. I definitely use a helmet when SUPing rivers. Once you're out of range of hitting your head on rocks, (Middle of a lake, far from a reef in the ocean). You can clip the helmet to the handle or cargo net for the rest of the ride.
-Direct your falls. If you're in the shallows, try to fall in a way that will make you belly flop. The sting that comes from a belly flop, will hurt less than hitting the rocky bottom. The more of you, that hits the water at once, the less you will sink on impact. Try to be completely flat when you break the surface tension of the water.
Good luck!!!