Kayak helmets come in full cut and half cut hulls, with the former offering more protection but the latter being more comfortable. The carapace can be made of plastic, Kevlar or carbon fiber, with the latter two being more expensive. The strap system should be easy to use and durable, and extreme whitewater kayakers may opt for full-face helmets for added protection.
There are two general categories of kayak hulls: full cut and half cut hulls. The difference between the two styles is the amount of coverage: full-cut kayak hulls extend low and cover the ears, while half-cut hulls do not extend low over the ears and end above the ears. The choice between the two is largely a matter of preference. Full cut helmets will protect the head more, but half cut helmets tend to be more comfortable and roomier. Both are acceptable options for kayaking, although whitewater kayakers may want to consider a full-cut helmet for additional protection.
The carapace is the outer shell of the helmet. Kayak hulls can feature shells made from a variety of materials, including plastic, Kevlar, and carbon fiber. In the past, most kayak hulls featured plastic outer shells, and while they were effective at protecting the head, they were prone to breaking on impact. Modern helmets may still have plastic shells, but Kevlar and carbon fiber shells are typically lighter and may resist breaking on impact more than plastic can. The downside to these higher-end materials is the price: both carbon fiber and Kevlar are likely to add to the price of the helmet.
An important consideration when choosing between kayak hulls is the strap system. This system keeps the helmet snug on the head so that the helmet does not move or fall off during use. It is important to test the helmet before purchasing to ensure that the strap system is easy to use and durable. Many modern helmets feature an adjustable fit system that will allow the kayaker to adjust the comfort of the helmet to their desired comfort level. The helmet must be snug enough so that it does not move excessively when the kayaker shakes his head vigorously.
Extreme whitewater kayakers may choose to wear full-face kayak helmets. These helmets feature an extension that wraps around the front of the face to protect the mouth and nose from impact. These helmets can be thicker and heavier than other types of helmets, so to combat the weight, many of these helmets are made from lightweight carbon fiber. Therefore, they are more expensive than other helmet models. A full face helmet is a good choice for a kayaker who will be navigating extremely treacherous rivers with many dangerous obstacles.