Hi again
Don't know if I'm just lucky but my system will hold its pressure for up to two weeks. If I leave the boat and turn everything off, come back after a fortnight and turn the power back on the pump still will not cut in. I have an accumulator tank but not a big one!
As another thought have you looked at the outlets from your sinks etc.
If you are able you could try to isolate your internal water system (either drain the tank or shut down the main valve) turn off the power to your pump and clear the water from your bilges. Give it a day or so, I know, not easy on a live aboard! But if the water is coming in as fast as you say you will not have to wait that long. If you don't fill with water your problem is the domestic side, if you do fill up its probably coming in from outside. If you are certain its coming in from outside the next step would be try and get the boat out of the water and hopefully the water will drip back out of the same hole. Then all you have to do is plug it! But I don't think life is that easy.
Good luck
John