Oh I have no doubts that it'll survive in a full sink overnight. I just don't want to assume that they'll handle a day of sailing with wind and water and crap crashing towards them.
I'm not sure of the manufacturer, but you can get them at MEC in Canada. They are the store's own brand. MEC is an outdoors type of store, that requires a 5 dollar lifetime membership. It's a perfect store for paddlers, hikers, campers, cyclists, and rock climbers.
Here's the website to the store,http://www.mec.ca
And to the lights (my price was off by a buck or so... whoops!)http://www.mec.ca/Products/product_detail.jsp?PRODUCT%3C%3Eprd_id=845524442621591&FOLDER%3C%3Efolder_id=2534374302692895&bmUID=1276726917414
I know they do take online orders, so maybe it's possible to buy them from another country, other then Canada. Not sure.