Ship's of wood and Men of iron.

Swedish square riggers, loading ballast at the ballast quay on the Fingringhoe shore, now the site of the WW2 pillbox, opposite Cook's Shipyard housing complex The ships bought timber to Wivenhoe, and for the return voyage to Copenhagen, they needed ballast to trim the ship for sailing.
There is in Copenhagen Harbour an island made of all the ballast these ships unloaded there, when they took on a new cargo.

Wivenhoe Memories collection.