Clinker - Another nautical word with many meanings. Clinker built is a phrase used to describe a boat building method. The edges of the hull planks overlap. This is a historic technique, traced back to the Anglo-Saxons.
The opposite technique, where plants but smoothly together, seam to seam is known as Carvel.
A totally different use of the word Clinker is in the manufacture of Portland cement. Clinker occurs as lumps during the cement kiln stage.