Can I reduce the pump output water pressure?

@battleboss you need to regulate your pressure after the pump. Pressure is resistance to flow, whereas the pump just provides the volume. You would have to add a pressure tank and pressure switch to your system. That would allow you to regulate the pressure up or down, depending on your needs. Since we do not know what specific pump you have or how the system on your boat is designed, it'll be difficult to give you the absolute right answer.