After losing a lot of knives to the river and finishing many river trips with only a small folding knife in my PFD pocket I have found a compromise that works well for me. It wasn't the cost of the knives as much as never knowing if it was going to still be there when I needed it.
I wear an astral greenjacket. It has 2 sliding panels and a gap between them. At about sternum level I zip tied my sheath horizontally. My handle protrudes out right just enough to be seen and easily grabbed but not enough to snag. I've had the same knife 3 years running. I've deployed it efficiently under pressure a few times just fine. I've had to finally sharpen my knife- rather than replace it.
disadvantages: It is harder to deploy left handed. I have to remember to put the blade sharp side down as it is mildly close to my neck and a train wreck of a deployment could conceivably get it close to my neck, though it would probably have to go through a shoulder strap to get there.
Always: orange fox whistle on a cheapo keychain carabiner and split ring in the shoulder close enough to blow without detaching. Strong enough setup that I haven't lost it, weak enough to break free if it somehow became caught, though I can't imagine how it could. No cord.
95% of the time I carry a salamander waist throwbag. When I kayak it is around my chest, when I raft it is on my waist. I put it on the exact same direction every time and practice the 2 likely ways I would use it before launching every time. I look stupid, like some sort of quick draw nerd, but I don't care. It has a quick release buckle. I have thrown it several times and while I can't gun it as far as a regular bag I basically always have it with me. Scouting, pee breaks, etc + no need to pop the skirt.
I was long ago swr certified and recertified. I wear a rescue vest. When I go kayaking with beginners who are likely to yardsale I add a stretchy cowtail with carabiner that is attached to my quick release system. It is generally non-locking because I choose the convenience of 1 handed instant usefulness over the extremely remote random attachment. This is especially true because If I am with beginners I am in water that I am extremely comfortable being in. Plus there is always the quick release option. Any other time I leave the cow tail home.
In my rear pockets I have 2 biners and mirco pulleys in one side and 2 prusiks and an anchor webbing in the other side. With my waist bag I have a light Z kit at all times.
The front pocket is another length of webbing and a locking biner. While rafting I add a frame tool. Then I usually have a waterproof lighter and a snack. And of course whatever else gets shoved in there. Camera, gloves, garbage.