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I am assuming you have panel mounted fuses also. If so:

The red goes to one fuse, them jumps to the other fuse. This privides fused power to the switches. There should them be a red wire from the fuse to each switch. The grey wires are the bow and stern lights as mentioned, and go to the nav light switch. You will have to determine which are the correct terminals on the switch. One popsition on switch works just the stern light, and the other works both lights. The neg return from the lights probably goes to the neg terminal on the fuse block. The ACC switch would have a red jumper from the fuse, and a some other color wire attaching to the switch, running to the accessory, depending on whether it is being used or not.