You have to swim when you are in a really big ledge hole or retentive feature. And you've been fighting it for minutes. And you have practiced being in and getting out of ledge holes.
And finally the pressure from the pour over pops your skirt and your legs come flying out. And there is no seam, or ramp to escape from. Then you swim. otherwise never swim. Don't hold on to your boat in the feature, its buoyancy kept you in there in the first place, holding on to it will keep above water for a bit but also keep you in the reversal. So, you got ripped out of your boat, enjoy the drowning I'm going to die feeling and go limp, always works for me. The river gods will hopefully take mercy and throw you rag doll style for a couple of circs and spit you out, where at this point, screw your boat and make your way to the shore like a scared wet little puppy dog. Count your blessings, let your bros or brogals get your boat while you recount the last 12 most terrifying seconds of your life. "I was in there for like 5 minutes man." Boats and paddles are replaceable, you are not. get out of the drink. Boof or swim, but learn how to make love to the seam. For the old schoolers you didn't boof the hole, you hit it and side surfed. know your holes. Old school kayaking videos have some great tips on how to avoid the swim. and phat soundtracks