The rail gun has the advantage of being nearly impossible to intercept. Exocets are subsonic, and as the British showed in the Falklands, not nearly as formidable as advertised. I remember in the 80's when everyone was up in arms about Chinese Silkworms being sold to Iran. Turns out about the only successful exotic weapons system they ever deployed was the F-14A Tomcat /AIM-54 Phoenix which took down a bunch of Iraqi MiGs, way more than they did in our service, including MiG-25's, during the Iran-Iraq War. Nice of the previous administration to sell them spare parts from our decomissioned fleet, BTW. (Please note the source)
http://www.foxnews.com/story/0,2933,248844,00.html The Phoenix, it should be noted, is a Mach 4 air intercept missile designed to take out both aircraft and incoming missiles. In US livery, the F-14A was able to carry six of them and fire all six simultaneously at different targets. The AWG-9 radar which made that possible was a re-development of the targeting radar employed in the A-12, the armed precursor to the SR-71 Blackbird. Iranian Tomcats can only carry four at a time, but still present a formidable threat to Navy F-18's and Air Force F-15's.
Rail guns are the new heavy surface artillery. My brother fires Tridents to end the world and Tomahawks to police it: boat bullets are bad business