I'm not sure the 2003 engines have NEMA output capability, someone will be along soon to respond. If it does, you'll need a Honda engine to NEMA cable, at least 2 "Tees", a drop cable to your Lowrance unit and end cap resistors. I have RayMarine electronics connected to my 2014 BF250, but I believe Lowrance sells a NEMA starter kit that has all but the engine cable. Remember though, NEMA is NEMA and not brand specific.
BF200- and BF225 serial numbers BAGJ-1600012 ~ Forward has NEMA
Honda part number 06328-ZZ3-760HE is the cable.
As Ken stated you need I believe 4 tees. One for the engine cable to plug into, One for a power supply and two to go to both gauges. If you already have a a NEMA under the dash you can just add to it with 3 One for the engine and 2 for the gauges.