Check this post

http://www.aws.org/cgi-bin/mwf/topic_show.pl?tid=12701

Charles is one fellow here who knows that business well

You use a welding rod that has been waterproofed by vynil(sp), wax, varnish, pvc, paint, or anything else that will keep the water out of the flux.  You'll be using a lo-hy rod, i.e. 7014 or 6013 which happen to be the most popular of the commercially available rods.  Then there's the companies that make their own rod, so you don't really know what makes them tick.  For the most part everything is down in the downward progression, bubbles go up, you can see where you are going and the company procedure.  The pay is like everything else in welding, depends on the company that you work for and the pay rate that that company has or what you've agreed upon.  For example I've been in the Gulf of Mexico welding for the past 10 years, and I make just over 100k.  But you have to keep in mind that you won't always be welding in the water, wet welding is a special skill.  Been lucky for the time that I've been out here I average 3 to 20 welding jobs a year. 

Charles Welch