Durham boats were flat-bottomed and double-ended, much like large bateaux in both construction and appearance. Beyond that, very little is known of construction details. No plans exist and likely they were not used. No extant remains have been found and very little written description exists. Probably they were built with heavy stems at bow and stern and a series of frames amidships, likely from natural oak crooks when available, and planked with sawn boards, likely pine although builders would have used whatever material was available.
https://en.m.wikipedia.org/wiki/Durham_boat
Wild wood !