Japan Becomes 1st Country Ever To Fire Electromagnetic Railgun From An Offshore Vessel::Japan has successfully test-fired a medium-caliber maritime electromagnetic railgun from an offshore platform, as it continues to advance its defenses in the face of burgeoning regional security threats.
From what I see, it looks like they never actually put the thing on a boat. All the testing was on land.
And after years of R&D the US Navy put the project on ice recently. Apparently they don’t think it’s worth the cost.