It may just be a simple way to vent the underseat storage area. With both the old and new bench in my 28, it would only take about a few days for things in there to start growing fur unless you pulled it open and let it dry out. Was the back bench vented into the cockpit in any way?

They went a long way to build an oddly shaped industrial duty, flanged fitting that looks like it came off of an aircraft if it's just a vent. It was IN THERE too. It took some effort to get it out.

Housing for the optional Flux Capacitor. If the boat doesn't have it anymore, might as well cut the price in half......