I've been kayaking whitewater since the mid-eighties, have been involved in several rescue situations, and have worked with the Whitewater Safety crew at the Ocoee Race Course. I like the Spyderco Merlin/Harpy as being the best blend of efficiency and versitality for a whitwater resue knife. The incident Joe described happened on the Ocoee River, a fixed blade was used, and the victim died of a severed femoral artery. Hindsight being 20/20, no blame was put on the boaters trying to do the rescue because the victim would have died had they done nothing. In that same situation, the Merlin could be used with thumb on top of the blade spine to control the depth of cut to no more than 1/4" (victims legs probably won't be where they should), and the sprayskirt could have been safely cut off. There are other safety aspects with the curved blade that will keep the edge away from the victim when removing clothes or cutting rope, webbing, etc. from tangled limbs, and they curve adds to the efficiency of the cut. This subject comes up about every six months or so, and if you do a search, you'll get a lot of different answers. Bottom line - take a rescue course, do some experimentation and situational thinking, then use the tool you are most comfortable with, based on your experience. After you decide, use it only for rescue, hope you never need it, and keep it easily accessable.