Along with the cog, another vessel appeared in the 12th century. This was the hulk. This seal dates to the end of the 13th century, about AD 1295. It is a seal of the English port town of New Shoreham, whose earlier name was Hulkesmouth. The scrip on the seal is in Latin, and reads: hoc hulci signo vocor os sic nomine digno (by this picture of a hulk I am called mouth thus by a worthy name).
It is thanks to this seal that we know what a hulk was. The picture shows a vessel with a crescent-shaped hull without a stem or sternposts. Instead, all the hull planking strakes run parallel to one antoher right up into the castles at either end of the hull, rather than into the posts.
So, the famous ship representation on the Winchester Cathedral baptismal font dating to 1180 is of the same type, and so is very probably a hulk! One can theorize that it is because the ship had no sternpost that the stern rudder had to be mounted off the longitudinal centerline.
The word hulk actually comes from Anglo-Saxon meaning "seed pod." The word hull aslo derived from the same word. So, possibly, the hulk got its name from the fact that it originally had a hull shape much like a pea pod.
Utrecht ship
There is good reason to believe that the hulk as a ship tpe developed like banana-shaped lowlands river craft consisting of a dugout log bottom and sides. Each side consisting of two planking strakes fastened together by a half-log wale that covers the same between them.
Notice that all the strakes in the hull run its entire length and all come together and are joined together by a rather small block of wood at either end of the hull, without a stem or sternpost.
This vessel was discovered at Utrect in Holland in 1930. It is 56.5 feet long and 12 ft broad, and dates to the late 9th century according to carbon dating.
Today, we believe that it is from river craft like the Utrect ship that sea-going hulks evolved. However, details of their deveopment are, at best, sketchy.
One theory is that because of the need for navigating in shallow waters, the hulk was developed out of a banana-shaped lowland river craft consisting of a dugout log bottom with attached sides. Here are two other river vessels that are part of the design transition arriving at the hulk. These vessels were quiet small.
Notice the flat bottom and long side strake.