Yesterday (15 June 2013) we got up early and headed up to Cunningham Sate Park in the Catoctin mountains just north of Frederick Maryland. Although I don't really consider the large hills around here to be mountains I gained an appreciation for the challenges other sailors have described related to sailing in mountain lakes. The lake sits in a bowl with trees and hills on all sides. This results in confusing winds with unexpected large gusts. The winds on Saturday were coming from all directions. It seems that I would just get the sails set and the wind would start blowing from the north instead of the east or the south. It got to where I just set the Jib in the center of the mast and cleated it off on both sides. This is probably why I ended up "washing the sails" for the first time. I was sailing along the north east end of the lake (by the dam) when a large gust of wind came up from the south. I hiked out as far as a could and eased out the main but the boat continued to tilt until finally, over it went. I quickly swam around the boat and grabbed the center board. I was amazed at how easy it was to right the boat, requiring very little downward pressure on the centerboard to bring the boat back to its upright position. While I was in the water I looked at the top of the mast and found that it was under the water but only about 6 inches. I had installed an eye ring at the top of the mast and attached a mast float airbag that I had purchased for around $20 from an outfit in England. The top of the airbag was standing straight up out of the water but there was enough buoyancy to keep the mast from turtling. I was back in the boat and getting the lines and sheets straightened out when the park ranger came over in his power boat to lend assistance. I made a few more trips up and down the length of the lake before calling it a day. Even though I had not intended to capsize the boat it was good to go through the experience so that I am now confident I can handle the situation if/when it happens again.