Sunday, 26 October 2014

Plimsoll Line

When strolling up the Embankment in London on Thursday I walked past a statue I must have passed 10s of times.  But this time I actually stopped, looked at it and realised it was not a historical war figure (most of them are around there) but Samuel Plimsoll. creator of the Plimsoll line.
14 10 23 Plimsoll (2)
The Plimsoll line, the line indicating maximum load levels, has prevented needless deaths at sea from overloading.  It seems obvious now but in the 19th Century it took him over 5 years before it became law.  It wasn't helped that many parliamentarians at that time were ship owners and deemed his proposal as a profit curbing exercise.   You can read Plimsoll's breach of order in Parliament (otherwise known as a rant - for all the right reasons) in the 1875 Hansard.
14 10 23 Plimsoll (1)
The symbols below are:

TF = Tropical Fresh
F = Fresh
T = Tropical Zone
S = Summer
W = Winter
WNA = Winter North Atlantic
and LR = Lloyds Register
14 10 23 Plimsoll (3)
The lines indicate the legal limit to which a vessel can be loaded for specific water types to safely maintain buoyancy.  Ships float lower in fresh rather than saline water so if they load to the fresh water line and then move into salt water with the same load, the sea level will align with the F and then the S as they float higher.  This classification obviously takes wave hazards into account which is why the least load is for Winter North Atlantic.  Mind you, I'd think Summer South Atlantic - Drakes Passage anyone? - would be pretty hairy.

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