Humber keels were constructed to a variety of sizes, between long and between wide. These different sizes were dictated by which part of the inland waterway network that the keel was intended to work on, having the maximum size hull that could get through the locks on their intended routes. They had strongly built hulls with a bluff bow and a flat bottom. The after part of the hull, in the region of the structural keel, was shaped to give a slightly concave run so that water flowed efficiently past the
sternpost and the rudder. Wood was used as the construction material for much of the keel's history. Clinker construction was the norm until the middle of the 19th century, when carvel construction was gradually introduced. Some were built with carvel bottoms and clinker sides. Typically, oak and elm were used for the planking and the timbers, with a
keelson (which was a major structural member) possibly of pitch pine, if not, of oak. Timber dimensions were generous, giving a heavily built hull. The wooden keels being built at the beginning of the 20th century had steel keelsons and iron knees. Iron-hulled keels were built in the latter part of the 19th century and steel hulls into the 20th century. The result of this was that in the closing years of working keels, wooden, iron and steel hulled vessels could be found working alongside each other. In the 20th century, steam and diesel engines replaced sail, with grants available to convert sailing vessels to mechanical power before the
Second World War. The dimensions of these craft were influenced by the gauge, or width, of inland waterways created or modernised during that period. In comparison to the widespread use of the
Narrowboat standard, far fewer inland waterways were designed to accommodate the larger Humber Keel gauge vessels. This standard is still used on associated waterways today. ==Notes==