Do you have a product which might help prevent corrosion inside a steel boat?

Yes! We can help address the corrosion concerns you expressed regarding the ship. Our company has over 28 years experience in providing real solutions for non-submerged, and non-buried structural corrosion problems, such as the inside hull of steel ships where conventional Cathodic protection systems are not able to function. We design and manufacture a wide variety of corrosion control systems, all of which employ a proprietary electrostatic corrosion control process, which we originally developed and patented here in the US, called "Capacitive Coupling". This proprietary process was specifically developed to address corrosion problems that occur on non-buried and non-submerged metal structures so it is a “good fit” to address the corrosion problem on the ship’s interior hull.
Our system has been proven effective at mitigating similar "open air" corrosion problems in maritime applications, aviation applications, ground transportation, mining, agriculture, and also for infrastructure in many different industries. The process has been shown to be very effective in extremely corrosive environments where the protected equipment is exposed to accelerated corrosion from salts, acids, high temperatures, high humidity and even wet and dry cycles.
 At the very least, three of these “corrosion accelerants” can exist on the interior hull of a steel ship. Before we can make a recommendation for a system for the inside hull of your ship, we would like to have some additional information including, the approximate total metal surface area, the general condition and metallurgy of the hull interior, (i.e. any existing severe corrosion areas or any dissimilar metal components or repaired sections, where galvanic corrosion should be considered), and the type of coatings that are currently being used on the interior. Also is there an existing Impressed Current Cathodic Protection system installed on the ship or are sacrificial anodes employed? The chances are very good that one of the 20+ commercial corrosion control systems that we routinely produce and stock, could be used "as is" or could be quickly and easily reconfigured to provide an economical solution for the corrosion problems that can occur on the ship’s interior hull.