Plimsoll and his mark

Samuel Plimsoll (1824-98) was a member of British Parliament, from Derby. In his time the general public was very concerned with the number of ships disappearing and sinking.
3 out of 4 British prisoners were sailors who refused to sail because their ships were in such unseaworthy shape. Can you imagine?

The traders from Venice and Genoa used to have good seamans' practice to mark ships with a loading line but this practice died out. Those are the same sailors who would beach their ship in storm, only to float it again in good weather! But OK, that was because they didn't have compasses yet to navigate on. At least they had the common sense to limit the load. I guess with all the navigational tools like compass, sextant, longitude and so on, the most basic seamanship was lost with the promise of profits.

Mr Plimsoll demanded that all ships should have a mark on its hull indicating how much cargo it could load during the various seasons. This 'signature' was made into law and applied too all ships visiting British ports and later all ships.
T = Tropics, S = Summer, W = Winter, WNA = WInter in the North Atlantic. So you can see that the north atlantic winter had the worst weather and the ship had to 'rise' to be able to have that line visible above water.

Amazing how an MP from a county with no coastline could have such a impact on global shipping!