the Head?

[kearleybe]

why is the bathroom called the head?

[Quizmonster]

In old sailing-ships, the toilet facilities used to be at the bow end...ie front or head...of the ship.

[sddsddean]

Almost right QM. The sailors used to 'do their thing' over the side. Now obviously you have got to get away from the deck so as not to soil it, so they used to squat on the beam that holds the anchor whilst at sea. This is called the 'cathead'. Head is just a shortening of cathead. Here is a piccy. http://images.google.co.uk/imgres?imgurl=http: //www.ussconstitution.navy.mil/images/cathead1 .gif&imgrefurl=http://www.ussconstitution.navy .mil/Catheads.htm&h=325&w=244&sz=55&hl=en&star t=2&tbnid=LHju-I2WnmPSdM:&tbnh=118&tbnw=89&pre v=/images%3Fq%3Dcathead%2Bship%26ndsp%3D20%26s vnum%3D10%26hl%3Den%26lr%3D%26ie%3DUTF-8%26sa% 3DN

[Quizmonster]

I just provided the answer as given by The Oxford English Dictionary, Sdds. It says: "A ship's latrine (in the bows)."
That usage dates to the middle of the 18th century, whereas 'head', meaning the fore part of a ship in general, dates back to two centuries earlier.

[sddsddean]

Not arguing that the head of a ship is the front end, but heads (as in loo) comes from the cathead.

[Quizmonster]

I'm not saying you're wrong, Sdds...all I'm asking for is evidence that you're right!
Your link provided a fascinating picture, but nothing to suggest the cathead was the latrine. Similarly, The Oxford English Dictionary gives a lengthy outline under the heading 'cathead' but not a bit of it says it was used as the latrine either.
Another part of old sailing-ships was the 'masthead'...imagine the deck if that was used as a toilet!
Over to you.