Kayaks come in two basic styles. You got Sit-on-Top (SOT) kayaks and you've got Sit-Insides and both are available as singles or doubles. They also come as hard shells or as inflatables.
Although there are some major differences between sit-inside and sit-on-top kayaks, they share many of the same parts. The top of the kayak is called the deck. The bottom is the hull. The front is the bow and the back is the stern. On top of the deck you'll often have deck lines or bungees.
At the stern of the kayak, you should find some grab loops and some kayaks have rudders. Rudders swivel side-to-side in the horizontal plane and are controlled by foot pedals. Skegs simple drops straight in the water and help the boat go straight.
Both sit-on-top and sit-inside kayaks have seats and some form of foot support, like the foot wells in this sit-on-top kayak. There are also foot pedals which slide on the track to adjust for different sized paddlers. Foot wells are convenient, but if you're going to be spending a full day on the water, you'll want to use foot pedals. They're a lot more comfortable and you get a lot more support from. The best kayaks will also have a built-in back rest, which makes sitting in a kayak a lot more comfortable.
The biggest difference between the two types of kayaks is that sit-insides are enclosed. There is an area called the cockpit where you sit. Around the cockpit is a cockpit rim where you can attach a spray skirt to keep water out. Inside the cockpit you will find a seat and foot-pedals that you can adjust according to you leg length.
With hundreds of options out there, choosing a kayak can seem overwhelming, but it doesn't need to be. And it's hard to make a wrong decision. The best way to narrow down your options is to identify how and where you'll be using your kayak.
Your first and biggest decision is whether to go for a sit-on-top or a sit-inside kayak. And there pros and cons to both.
Sit-on-tops are the most user-friendly. They're very stable, easy to get in and out of and there is no feeling of confinement on them. They're also self-bailing, which means they have small holes (called "scupper holes") that allow the water to drain right through them. Another big thing about sit-on-tops is that you can slip on and off them as you please. All these features make the sit-on-top kayak a great choice for nervous paddlers, for warm environments and for paddling with kids who love to swim.
The downside to sit-on-top kayaks is that you're guaranteed to get wet while paddling, while sit-inside kayaks allow you to stay dry.
Sit-insides shelter your lower body from the wind, which makes them much warmer. Sit-inside kayaks are great for paddlers who'll be on cooler water and who want to stay dry while paddling, and they consider the kayak more than a vehicle for travel than a toy.
One downside of the Sit-inside kayaks is that you don't have the same freedom to move in and out of the water. And if you do flip for some reason, recovery is a complicated process because your kayak will likely be filled with water.
Like sit-on-tops, recreational sit-inside kayaks are very stable, fun, and easy-to-use. They've got large cockpits so there's no reason to feel confined in them. Some even have waterproof compartments that are accessed through hatches in the deck.
Once you've decided whether to go for a sit-on-top or sit-inside, you'll need to decide on the length of a kayak. It's a general rule the longer and narrower the kayak is, the faster it will travel and a wider kayak is the more stable but slower it will be. Most sit-on-top kayaks are considered recreational (or "rec") kayaks because they're wide and ultra stable.
Sit-inside kayaks can vary a lot more in shape and size and in purpose. In fact, sit-inside kayaks can be broken into two distinct categories, you've got recreational sit-inside kayaks, and you've got touring (or sea kayaks). The recreational boats are wider, they're shorter, and they have these big cockpits. So they don't feel confining it at all.
The touring or sea kayaks are longer, narrower, so they're a lot faster. They also have thigh hooks or knee-cups that can give you a lot more control over the edging of the boat. The cockpits are a lot smaller. So you tend to feel a bit more confining, although it's very easy to get out of these boats as well.
If speed is not important to you, let us now choose a shorter kayak, they're lighter, and they're easier to move around.
Most kayaks have a hard shell made from a durable plastic that'll last forever and it doesn't require much maintenance. There also kayaks made from composite materials like, fiberglass, carbon, and Kevlar. They make them significantly lighter. The downside, is they don't take abuse as well. They also tend to cost a lot more.
You also have inflatable kayaks like this one from Innova. They're very comfortable to paddle and they can be deflated, rolled up or folded down and actually carried in a backpack. These kayaks are made with coated fabrics and are surprisingly durable. Inflatable kayaks don't tend to be as fast as hard-shell kayaks, but they are incredibly versatile.