Sea kayaks are designed to handle well in open water and for paddling longer distances.
Here is a list of books and other texts related to kayaks, kayaking, kayak design, boat design, woodworking and boat building that may be of interest to anyone interested in building their own kayak.
Touring boats have two requirements, they need to have room for gear, and they need to be able to cover distance efficiently. Room to carry gear is primarily a function of boat volume, to more volume, the more room to carry gear.