Mainship 400 Twin Fuel System
After doing some staring, experimenting, and screaming, it appears the Mainship 400 twin has exactly the same fuel system as the Mainship 400 single engine. With no means to shut down the crossover line, I can't isolate the engines to their respective fuel tank. In theory, each engine pulls from the tank on the side of the engine because there is less resistance. By the end of the summer I will put a valve on that crossover line.
That brings us to the list...
My theory was that the batteries and generator on the port side caused the list. As the boat sat in the slip the fuel would migrate by gravity feed from the uphill to the down hill tank via the crossover, causing the port list to increase while tied up.
Last year I moved the two 8D batteries to the starboard side for about a net 450 lb shift around the axis. List just about went away and doesn't increase in the slip any more. Also, fueling is much easier without "burping" the vent lines.