Fixed tenon and single mortise: A tenon was shaped from the end on one timber and inserted into the mortise of the other. When the tenon of a large vertical timber was left unlocked, as in masts, and sternposts, it was said to be stepped.
Free tenon and two mortises: The most common method of edge-joining planking in ancient and early medieval vessels in the Mediterranean area, it also was used to secure adjoining surfaces of parallel timbers, such as stems and floor timber chocks. Corresponding mortises were cut into each planking edge; a single hardwood tenon was inserted into the lower plank and the adjacent plank fitted over the protruding tenon. In many instances, the joint was locked by driving tapered hardwood pegs into holes drilled near each strake or timber edge.
Free tenon and three or more mortises: Used in superstructure fabrications or places where hull planking was too narrow to provide sufficient seating for the desired tenon length. Al through small planking joints whose tenons are unpegged and contribute no structural strength are essentially coak joints, the term mortise-and-tenon joint has become universally accepted for all such forms of edge joinery.