Saturday, May 30, 2009

Weekend Puzzler: Navigation Shapes

Ok, pop quiz for all you expert sailors.

1. What do those three black shapes in a line on this vessel mean?

2. What would this boat show at night in addition to its standard running lights?

3. What is it probably doing?

Follow up, more general, question tomorrow!


O Docker said...

Geesh, JP, no one remembers what any of those day shapes mean without looking them up.

The only one I remember is three cylinders in a vertical line which means they're having sausages for lunch.

But, I'd guess he's looking for some guy without a shirt riding a bicycle on some pontoon floats.

Tillerman said...

Based on my deep knowledge of all things nautical I'm going to take a wild guess and say he's doing some kind of survey?

JP said...

Student CA-12345. This is of course a meaningful answer (not necessarily correct of course) but to question 31-05-09 not to question 30-05-09, so hence you get a total score of 50%. Alas the minimum required to pass is 51%, very sorry etc

Student RI-54321. Congratulations on your reading skills! With the current low bar of educational exams that gives you also a score of 50%, but alas see comments above on the minimum required to pass.

Pat said...

Given the word "SURVEY" stenciled on the side of the boat, do you think your readers had enough of a clue?

Tillerman said...

Oh, thanks for pointing that out Pat. I didn't see that. A bit subtle but not a bad clue really.

O Docker said...

You know, there's all kind of detail in this photo, if you're a careful enough observer.

I'd be willing to bet it was taken on a Friday.

JP said...

Spookily correct O Docker!

Ok, a good journalist never reveals his sources but any chance of a clue as to how you got that?

O Docker said...

Why not throw it open to your readers, JP? How did I know that?

Another clue tomorrow.

Carol Anne said...

I looked closely, but I did not see any fish. However, I do wonder why a boat from Liverpool is in the Thames and not the Mersey.

Now, when I lived in England, there seemed to be this tradition that on Fridays, people would tend to take lunch at the local pub and not get around to getting back to work afterward. Perhaps the Natural Navigator could look at the reflections on the water and come to the conclusion that the survey boat was leaving the survey area while the sun was still high in the sky, and therefore it must be Friday.

But I suspect O Docker had some inside information.

O Docker said...

Nice analysis, Carol Anne, but it wasn't the one I used.

If I also said the photo was taken with a Canon EOS-350D, would you know the identity of my source?

JP said...

Oh dear, O Docker, I'm afraid I'm having second thoughts about your source.

According to your mole, known only as Deep Pockets, the picture was taken at 00:50 hours where as the picture clearly was taken during daylight hours.

So either your source is being "economical with the truth" or the camera was actually operating on Californian time!

JP said...

Oops, my bad, the old plus vs minus problem.

My camera is of course on Japan time not California which makes a lot of sense given the other clue you posted.

O Docker said...

I guess not everyone realizes all of the information that travels along with their digital photos when they post them online. The iPhone can be configured to record the GPS coordinates of a photo's location, so the unwary could be posting a breadcrumb trail of their whereabouts when they put an album up.

Sorry if this has led so far off-topic, but maybe it hasn't really.

I think one of the reasons those day shapes are so ignored these days (although they're still required, technically, in many jurisdictions) is that later technology has made them obsolete. I don't know what local practice is on the Thames, but in San Francisco Bay, for example, commercial vessels report their movements to a vessel traffic service which, in turn, tries to keep ships apprised of crossing situations. A survey boat like the one pictured, constrained in it's ability to maneuver, would have reported in to VTS which, in turn, would have alerted any large ship closing on that location, long before any day shapes could be detected visually.

Bowsprite has posted quite a bit about commercial VHF chatter in New York harbor - it can be colorful and funny, besides being practical.

But the new thing is AIS - about which I'm hardly an expert - that broadcasts all kinds of information about a ship's identification, type, location, course. speed, etc. - much like the data your camera has captured about the photo you posted. How's that for closing a fairly far-fetched loop?

Carol Anne said...

Gerald's camera is a Nikon rather than a Canon, but I imagine it collects similar information and attaches it to the photos.

Does this mean I need to be scared about the shots he took this weekend that show things I'd rather the world not know exactly when happened?

Actually (sigh of relief), I realize that I have pictures from when he was a toddler that I can use as blackmail ... he releases some shots; I release others -- to his girlfriend and/or her parents!

JP said...

Someone once said that all you needed to create a 1984 style police state was to give everyone:
- a mobile phone
- a credit card
- an email account

Though even they hadn't thought of the dangers of an iPhone with built in GPS

O Docker said...

And wouldn't you know it?

Almost on cue, Bowsprite posts this.

I think her data on the ship was relayed by her friend Tugster who presumably had AIS onboard.