I own and use a paddle surf and 3 person un-sinkable kayak (ridgid, open top, not the best for navigation but suits my use). I do have several PFDs but I must confess I rarely use them... because I always (ALWAYS) put on a full body neoprene wetsuit. Either freediving suit (high waist pants + jacket) or long sleeve surfing wetsuit. They float more than enough to keep me on the surface and the most important... they keep me warm. I don't have much fat on me and wather in my area rarely gets above 20ºC, not even in late summer.
The wetsuits also offer mechanical protection against bruises, cuts, and abrasions. Wet things are slippery and wet skin softens, so it is a bad combination. Sometimes the molding of a kayak has sharp edges, and they cut!
This applies to wether I am paddling recreationally OR when I go spearfishing with the kayak. Everything is tied to the kayak so if I ever capsize, I don't loose stuff. Maybe the only exception could be the weight belt. It is either on me the whole time or I unbucle it and let it rest on the back of my seat, ready to put it back on.
When we go spearfishing on a boat (I don't own one) I put the wetsuit onshore, no matter how hot it is or how far we need to navigate before jumping in the water. I am terrifed at having to stay for a long period of time in the water with no protection against cold. Most of the people I know, put on the pants and keep the jacket aside to put it on when we arrive destination. But I don't like the idea.
However, anytime someone else comes with me in the kayak, they either get the same setup as I use (full on wetsuit) or a PFD. If hey are kids, then it is wetsuit (surf) + PFD no questions asked. I do trust my diving buddies but I don't trust a 9year old kidd doing something stupid.
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