I have a 1977 and bought a new negative buss to mount behind the dash and a new positive with spade fuses buss and intend to run the negative black to that buss then the positive red to that buss from the battery and distribute a negative to each electric device from the buss and after the fuse, a red + to each device so it goes through the fuse on the positive, red side. That's the way I remember my big sailboat was wired and I hate those round glass tube fuses. Modern spade fuses are much easier. If my thinking is backward let me know. I have not crawled into the cuddy yet to check it out, just know I want different at this point. I chose to have a separate negative buss which I'll mount and bring one heavy wire from battery to it and then a separate with spade fuses positive (red) buss with a heavy red wire from the battery. From that I will run a black to one side of a switch or device and after the fuse a red to the other side of same switch or device. It's like a loop and the fuse goes into the red side of the loop. I'm quite content with two separate busses unless I've completely forgotten how to do this.

basic diagram of what I plan to do
 

This diagram is how I plan to do mine. The wires in place I will trace with power source and meter/probe, label then run from battery to the busses forward then to each device from the busses through the fuses.https://www.google.com/search?q=wiri...RkS-LlJkyHM%3A

a simple diagram of what I'll do
 

This is a clear and simple diagram of what I'll do...if I can upload the photo correctly

Usually... a new fuse panel has a neg bus already attached.

search for the thread "new dash ideas" or Tag search "Dash" or "electrical"
You'll get some good info, pix, and ideas

Also might want to wire in a float switch directly to + side of battery with an inline fuse, so bilge pump is active even with the selector switch in the off position.

electric wiring
 

I had decided not to put a battery switch inline as some haven't with one battery but remembered you can add a simple switch which mounts to the negative battery post and which the negative cable attaches to it. When you want it off to the boat just turn the knob on top and it breaks the connection. Cheap, simple and better than leaving something on inadvertently when you leave the boat for a while and it's not in a slip, etc.