I had a similar issue when I commissioned this spring. First you need a really quiet boat and a full water tank.
IF when you first turn the pressure water system switch on, the pump comes on and stays on, you either have a disconnected hose, the hot water purge valve is open, a faucet is open, or you have another leak in the system. The pump running continuously with all valves closed indicates a water leak . . . the system is trying to pressurize, but doesn't.
IF when you turn the pressure water system switch on, the pump runs momentarily and then stops, your system has pressurized. If you're still just getting a small amount of water out of individual fixtures, then I'd check the screens in the individual fixtures, as well as the screen ahead of the pressure pump in your bilge.
When I started the system in the spring I had forgotten that we opened the hot water tank relief valve to blow the air out of all of the lines. So we ended up with a clean bilge until I figured it out!
Best of luck!
Bob.