lighthouses are always round

[darth vader]

Why are lighthouses round? what is the structural advantage to building a lighthouse round and not rectangular, as other buildings seem to be. (ps hello all the other regulars sorry i have not been around for a month but a) i quit my job b) i am enjoying myself too much to be on ABank - there is a place you can talk to me if you wish, i forget the URL, Indiesinger what is it again??? :-)

[norfolk boy]

theres a lot more strength in a round building.

[secretspirit]

Maybe because they put them on a small piece of rock it's better because not so much surface area is required to build one. Plus once sailors got used to looking for that shape building it would look odd, and a tall tower is a distinctive shape to spot in bad weather. Actually that bit was a pretty stupid thing to say - I expect the big shiny light is the first thing they look for!

[rekstout]

A round shape will weather wind and waves more easily as crashing waves will flow around it.

[IndieSinger]

Ooh *scratches head* I think the link you're after is http://uk.groups.yahoo.com/group/Answerbook. Good to have you back, darth :)

Oh and... um... "lighthouses"... or something. (Need to keep the post on-topic...)

[darth vader]

hmmmm. well spotted secretspirit i would imagine the big shiny light thing would give it away :-) Don't think round is a very efficient shape for minimising surface area but there you go. Perhaps the areodynamics come into it (rekstout) but i think there is more to it than that - easier to build? easier to maintain? will hold out for other answers.

[archbishop]

The lighthouse on Bardsey Island is square.

[pinus]

For a given perimeter, a circle has a greater area than any rectangle. Partly the possible shape will be determined by location. A lighthouse atop a cliff could have a square tower, but one set on a rock (Bell Rock, Eddystone, Skerryvore, etc) has to be designed in a way to minimise the effects of wind and waves on its structure. Defining the curve from base to top for such a lighthouse is yet another complication. On land, the tower can be cylindrical, or the frustrum of a cone.

[pinus]

I got interrupted and posted that without completing the last point. Defining the curve from base to top for such a lighthouse is yet another complication. On land, the tower can be cylindrical, or the frustrum of a cone. At sea, the tower has to be curved, so as to dissipate the force of the waves. I can highly recommend "The Lighthouse Stevensons" by Bella Bathurst. It tells the story of the building of Scottish lighthouses by the ancestors of Robert Louis Stevenson.

[Toffee]

The lighthouse (pharos) at Alexandria, one of the seven wonders of the world, was square if you believe the depiction on:-http://ce.eng.usf.edu/pharos/wonders/list.html

[Toffee]

Pinus, I found your explanation very enlightening (no pun intended!) and interesting. I don't think my interest extends as far as poring through the book you recommend, but thank you very much nontheless.

[loop]

The Lighthouse In Alexandria Was Square.

[darth vader]

just in case there is any confusion - i don't give a rats arse for square lighthouses hence the word square never appeared one single time in the original question, in case anyone is still in any doubt?

[archbishop]

Isn't a square a rectangle which you do mention in your question?

[darth vader]

a square is a rectangle correct. But i never said the word square in my original question arch. (you're just winding me up aint you?). thanks for the answers folks i think it's pretty safe to say the aerodynamics of being able to withstand the sea/wind is the main reason. question closed. Darth

[archbishop]

Yes