Grab Loop A loop of rope or webbing at the end of a boat, useful for boat recovery. A swimming paddler can hold onto his boat using a grab loop. Grab loops should be securely attached to the hull, and large enough so not to entrap a paddler's hand.
Gradient. The amount a river drops over a given distance. Usually measured in feet per mile or meters per kilometer. The steeper the gradient, the more intense the whitewater.
Hairboating Boating within a hair's breadth of disaster. Boating over your skill level, or boating extremely dangerous stuff. To some a mark of honor, to others, a mark of low self worth.
Haystacks Big standing waves that are breaking on their up current face. Many rapids will have a series of haystacks down current of the main chute. Riding these is much like bouncing along on a roller coaster, and can be a lot of fun. Haystacks are a pretty benign form of whitewater, and are fun.
Holes, Hydraulics, Reversals and Stoppers Water moves over a ledge or obstruction and drops sharply until it hits the bottom of the river. The deep flowing water moves down river along the bottom until it runs into slower moving water. There it is forced up to the surface. Some water goes down river; some flows along the surface back upstream toward the ledge. This creates a hole in the river.
...Some are gentle, some violent. Some are fun to surf and play in; others are deadly. They can keep you and recirculate you for the rest of your life. Learning to tell them apart is part of the skill of reading water. Often, the ones that are most dangerous don't look so. Low head dams are the most common river killers, yet they don't look like much to the uninitiated. Natural ledges can kill. The first drop of Woodall Shoals on Section IV of the Chatooga River looks like a class 2+ rapid, yet has killed many paddlers with its lethal sticky hydraulic.
Hull Shape Under development
K-1 One person kayak; K-2 Two-person kayak.
Kayak A small, decked watercraft usually paddled by one or sometimes two paddlers. The paddler sits in the boat and paddles the craft with a double bladed paddle. Based on the traditional watercraft of the native peoples of the North American Arctic.
Keel In classic boat building, the keel is the backbone of the boat; a spine that runs from end to end along the bottom of the boat. Most modern canoes and kayaks do not have keels. Aluminum canoes and some general purpose canoes do. The part of the keel the projects below the main hull does help the boat track (go straight). It also adds drag and makes the boat difficult to turn. Tracking can be improved using other design elements.
Keel Line The line of the keel would follow, if the boat had one. An imaginary line running down the middle of the boat from end to end. Often used as a reference line when describing maneuvers.
Kevlar A strong fiber manufactured by DuPont, used in combination with other materials to produce a high-strength, lightweight product. Expensive. Applications include high performance aircraft wings, bulletproof vests and racing sails.
Knots for paddlers There are four knots leaders should know: the bowline (loop knot), the figure-8 (loop and stopper), the truckers' hitch (ties boats to cars) and the constrictor knot (no-slip knot ties to water bottles and other gear).
Advanced: Knots needed for swiftwater rescue include the water knot (joins ends of flat webbing), the double or triple fishermans knot (used to make Prusik loops), and the Prusik knot and the girth hitch (used to make adjustiable haul lines).
All of these and many more are fully shown at the excellent website animatedknots.com.