summer line

[corvi]

 

I'm really fond of the sort of cryptic markings we leave on things to convey technical information. It seems like a sort of magic. I like looking for the loadline marks on the boats when taking the ferry to work. 

The circle with the line through it marks the summer line, the legal limit of how heavily this ship should be loaded; if the water is above the line, no good. AB is for the American Bureau of Shipping, which assessed this particular boat. The little staircase thing to the right shows the permissible waterlines in other circumstances: F for freshwater (which is less dense, a ship that floats at the freshwater line in fresh water will float at the summer line in salt water) and C for when passengers are on board.

There are lots of weirder steps you can have on the staircase, though, which I keep an eye out for: steps for "this ship is set up to dump its cargo if it runs into trouble, so it's allowed to carry extra cargo", steps for tropical waters and for ice-choked arctic waters, for various combinations of passengers and cargo. It's like looking for license plates from various states or provinces, but for people who take a boat to work. 

Comments

[beaq]

!

[ivy]

Those are interesting; I appreciate the drive-by decoder ring. Thanks!

[gfish]

I didn't know those -- awesome!

I have a particular fondness for temporary utility discovery/construction layout lines spraypainted on roads. They're like glyphs that summon civic improvement.

[twoeleven]

I've seen Plimsoll marks before, but hadn't noticed the staircase thing before. Thanks!

Railroad cars sometimes have mysterious markings, and some that are clear but ominous, like "only couple at end of train". Alas, I have no idea why that's sometimes spraypainted or stenciled on them, but it makes me wonder.

[corvi]

Oh man, I bet railroad cards have some awesome glyphs. Excuse me, I need to go google a bunch of stuff.