The hynautic system is normally pretty reliable. i m pretty sure the sea star KE4 is the same and the older Morse electronic controls. I used...
One way to troubleshoot which I considered but the boat sold before i had to do it, would be to hook up a dock hose as close to the tank pick up...
Again not familiar with super yachts but on smaller boats like the 110 I run, insulation is much worst than a in a home also, under a home the...