HV upside down stuck ! (underwater) help please?

Just build a HV and wanted to move it a little further to add some parts on below side, but right away it went to sea , turned upside down and now i can't save it. I tried everything , put thrusters everywhere, digged the seabed around... is there a way to save this or is it gone? it just doesn't move at all, a few very very little turns to right and left side, thats all.. it doesnt turn to normal stance. that was a lovely map i created... (survival mode)

SCREENSHOT...

HV upside down stuck ! (underwater) help please?