The shafts of hand whaling harpoons was made of soft
iron. This had enough tensile strength to be able to pull the boat
without breaking, but was soft enough to be able to bend fairly easily
under the strain. Bending meant that the pull on the head of the harpoon
was directed through an angle depending on how it entered the whale,
and the angled pull meant that the harpoon was less likely to come out
and so the whale be lost.
All whaling ships therefore, right up to the industrial
days had a blacksmith on board and part of his job was to re-straighten
harpoons so that they could be used again.