Hey Horncologne - I happen to be one of those "sand sculptor professionals". There are many factors that come into play -- some kinds of sand will stand better than others. High silt/clay content is important - the clay holds the moisture in longer. But to really make a sand sculpture last, spray a light solution of white (non-toxic, biodegradable) glue diluted with water on it _after it has been carved. They do this in Harrison Hot Springs (home of the world championship and tournament of champions) and keep the sculptures standing for months. (See harrisand.org.)
For more sandsculpting tips just in time for summer vacation, take a look at sandcastlecentral.com. :)

Our uke group (the Saturn Street Strummers of SPI) plays pirate songs in pirate gear and we are quite formidable if I do say so myself (and I do.) This seems like a natural to add to our cover set.

Arggghh!