Marine electronics must survive constant moisture, salt spray, vibration, and extreme temperature swings that would destroy regular consumer electronics within weeks. Marine-rated equipment uses specialized coatings, gaskets, and materials engineered specifically for the harsh saltwater environment.
Installation requirements are completely different too. Marine electrical systems require proper grounding, corrosion-resistant connections, and wire routing that prevents chafing and water intrusion. Using automotive or home audio components on a boat is a recipe for expensive failures and potentially dangerous electrical problems.
The cost difference between marine and consumer electronics reflects the engineering and materials required to deliver reliable performance in one of the most challenging environments on earth.