The Byblos Ship 4: Fighting Hogging
Updated: May 2, 2020
One of the most prominent characteristics of Egyptian and other ancient ships is the way their builders attempted to fight hogging. But first a few words on what hogging actually is.
As ships tend to be wider in the middle, displacing more water there, the lift is stronger amidships. When this is combined with the fact that the bow and stern are usually heavier and the bending that waves cause during a sea voyage, ships tend to gradually ‘hog’ in time. Their shape bends causing the bow and stern to drop and the middle to rise, much like the back of a hog. This ever present issue is what is known as ‘hogging’.
Most wooden ships resist this with the help of their thick keel and dense frames, which, as we have said, are absent in ancient Egyptian ships (Image 2). Ancient Egyptian shipbuilders used a hogging truss, a set of ropes that extended from bow to stern and counteracted the effect of hogging. The truss is clearly visible in the ancient reliefs from Sahure’s grave complex (Image 3). A very similar device, incorporating steel wires, was still used on American riverboats in the 19th century, which also lacked a keel. The wires are clearly visible in image 1, stretched over a series mast on the ship’s top.
Ancient Egyptian sculptures depict in great detail how the hogging truss was installed and made taught over a series of vertical supports. Two strong logs were attached laterally at the bow and stern, held in place by ropes going around the hull (Image 4A). A set of ropes (probably 6 in number) were tied to the two logs, running through the length of the ship over vertical supports. A pole was passed between the ropes amidships, which was twisted to make the ropes taught and was then tied to one of the vertical supports (Image 4B). The taught truss held the ship together in this way like the string of a bow.