Tried unsuccessfully to free a bird wrapped in fishing line. No knife. I don’t like carrying a knife on day paddles for fear of cutting myself. This was the first time I needed it in 30 years of paddling. But a bird is dead, so reconsidering. Folding or not? What length blade? Attach with cord to pfd, or risk dropping? Consider day paddles only, no camping.
You will find as many answers as people you ask. I carry a 2 1/2 inch blade folder with a blade lock and a pin to open with one hand tied to my pfd. I have thought of also carrying a small scissors tied to the boat for incidents like you describe. If you have a knife, a sharp knife is safer and more useful than a dull one.
Dive knife or a river knife. Like below. Fits inside a pocket of many PFDs and the dive knives have a blunt end. No maintenance of joints or moving parts.
If folding, make sure there’s a strong reliable lock! I’ll never use a folding knife without one after a few close calls with blades collapsing on my fingers. I can’t imagine trying to screw around with a folding knife on (or in) the water…
I carry two - an Aqua Lung clipped on my PFD, which I have always thought I should put a tether on too, and a Mora Companion fixed blade, in stainless steel (because it often stays wet).
I don’t recommend the Mora for use on a PFD as it is extremely sharp and there’s a pointed tip. Not to mention the clip doesn’t work well with a PFD (I lost my first one into the deep this way). They’re quite inexpensive for the very high quality that you get, so losing or damaging one isn’t a huge deal if it happens.
The Aqua Lung, and many other river/paddling blades have a blunt tip that’s safer to use.
I favor a Spyderco Salt series folder in my PFD. Zero rust ever.
I have no a Gerber River Shorty. Carried it for years and only used it, so far, to cut tangled fishing line hanging from a tree.
I carry this in a pfd pocket. I have a floaty thing attached to it so it won’t sink. It’s OK. I wish it operated one-handed as nicely as my every day Gerber folder.
NRS Co-Pilot Knife on lash tab of my PFD. Bought just in case I ever got caught in a strainer. Regularly use it to cut fishing line dangling from tree branches. Saved me quite a it of pain when I paddled into fishing line with hook dangling.
I also carry a Spyderco Salt, with a serrated blade. Never had any rust, still very sharp. A little more expensive than some options, but seems to be worth the cost to me.
I have been carrying a knife since I was twelve. On the boat I often have three, a folder(pfd.) a sheath(deck bag) and multitool. There is also often a folding pruning saw for low limbs. I leave the blunt nose kayak knife on shore. Stainless steel blades are better than carbon steel.
I carry two. Short blunt end, with combo serrated and straight edge which is on my PFD. It’s sole purpose is reserved for cutting myself out of a line entanglement. Haven’t had to use it yet, thank God.
The other is a folding, locking, long blade (3.5 "), Swiss knife. A lanyard goes around a belt loop near my front pocket. A stainless steel quick release connects the knife to the lanyard. Makes the knife quite accessible and still secure. Push one button and the closed knife releases from the lanyard. The long blade reaches to the bottom of peanut butter jar, cuts cheese, fruit, etc. Useful for non food tasks as well. This knife gets a lot of use.
My local paddle frequently has abandoned tackle in the tree line. On those days I’ll carry a fixed Mora knife on my belt. – 4" blade, hard plastic scabbard which clips on my belt. Makes it easy to get to the dangling line and quickly cut it off.
Worries about cutting yourself are important to think about; you must be knowledgeable and mindful about safety when using knives.
Agree with the dive/rafting knife recommendation because of the blunt tip. I currently use a Benchmade H2O: http://www.benchmade.com/h2o-fixed-family.html. Also agree that fixed blades of good quality are best: my last knife hung a PFD for 18 years. It outlasted 2 PFDs. I never did anything more than rinse it in fresh water once or twice a season.
Folders have their place, but they tend to accumulate sand/grit in the mechanism and need more maintenance. Also, sitting in pockets unused for months tends to allow stuff to clog the locking mechanism if you’re not careful, increasing the chances the lock won’t hold.
As for a tether, I keep one attached to a pocket of my PFD with a locking micro 'biner in the end of a 1.75mm Dyneema line. Most of the time my knife is untethered to avoid more stuff to get tangled in on the outside of my PFD. But if I ever need to, I can quickly clip the carabiner to the tether and prevent loss.
Spyderco Salt serrated folder, been in my lifejacket pocket for 10 years, and still looks pretty good.
I use a Spyderco too. They make a great folder that opens easily with one hand and locks up solidly. With a little practice you can also close it easily with one hand.
If you don’t want to spend that much you can get a Gerber Paraframe for under $25. It will rust - especially in salt water - but if you’re not getting wet that much it’s a viable option if you take good care of it.
As a scuba diver I have a few fixed-blade dive knives but for kayaking I’m very happy with a folder in a PFD pocket.
Oh, and if fishing line is your main concern, you might like some stainless scissors. Many divers that I know use them…