My boat came in two versions, one the inboard diesel, and the other the outboard. For some reason the outboard version did not come with a main battery switch, so the electrical fuse panel and VHF are always powered, and everything just gets attached directly to the battery terminals. Since before I bought the boat I’ve planned to install a battery switch, clean up the wiring and just upgrade the electrical in general. It took me quite a while to figure out how I wanted to do this, but this spring I finally decided what I wanted to do. This is part 1 of the electrical system upgrade. Part 2 will be replacing the 5 position fuse panel with a custom made breaker panel from Bass Electric later this summer.
Below is the decided upon design. I purchased 100 amp bus bars for the main power distribution as I think my max non-starting draw with everything on and the VHF transmitting is around 25 amps, but as I don’t know exactly how many amps the engine draws when starting I decided to stay on the safe side and attach the engine cables to the same terminal posts on the bus bar as the power feed cables so the engine starter cables would be directly attached to the battery feed without drawing through the bus bar.
EDIT: see the post about the inverter installation for additions to this system
The two batteries sit in battery boxes in the stern on the starboard side, and the engine controls and start / charge wires from the engine reside under the port side hatch. I decided I wanted to mount everything on the bulkhead above the batteries, but due to the thickness of the bulkhead, I could not screw into it without the screws sticking out into the cockpit, so I needed to mount a piece of plywood to attach everything on. Also the shape of the bulkhead requires 2 separate pieces. I found a remnant of nice 3/4″ hardwood plywood at Home Depot for $1 that is perfect for the job.
Since the battery switch will put frequent torsional loads on the screws when turning on and off, and is something that may be removed and re-installed a few times over the life of the boat, I didn’t want to use a wood screw that may eventually work loose or strip the hole out so I decided on 1/4″ machine screws threaded into Tee Nuts on the back of the board, and since the board needs to sit flush, I countersunk the Tee Nuts into the back of the board.
Close up of the countersunk Tee Nut
Prior to installation I sealed the front and edges of the board with West Systems epoxy using the 207 clear hardener to help prevent moisture from getting into the wood and rotting it. When I was ready to install the board I covered the back of the Tee Nuts with a small piece of tape so the epoxy did not get into the threads.
Here is everything laid out before heading to the boat for installation.
Since the whole reason for using the plywood is that I was attaching to a thin bulkhead that I didn’t want to drill holes in and have the screws coming out in the cockpit, I needed to epoxy the boards in place. Since epoxy takes a while to cure, I really did not want to sit there and hold the board in place for an hour or more. I used the 205 hardener, but the air temp was around 45 degrees so the set and cure time would still be rather slow. I picked up some $4 spring loaded compression type curtain rods from target that would fit between the plywood and the hull to hold it in place while I left the epoxy to cure overnight.
I cleaned the surface and washed with acetone, then test fit the boards and compression poles, adjusting the lengths to keep a nice firm pressure and hold everything in place. Once I everything had been test fit, I mixed up the batch of epoxy and set it aside for a few minutes so it would begin to setup, and applied a strip of masking tape along the bottom edge of each piece of wood to prevent epoxy drips, then brushed a thick coat of epoxy on and stuck the boards in place with the compression poles holding them in place overnight.
The next day I returned to the boat and installed everything on the new boards. The small terminal block at the top connects the wires from the solar panel to the input side of the solar charge controller. Having the two separate boards also serves to create a “always hot” area that can potentially always have voltage, and a switched area that never has voltage, if the battery switch is in the off position.
I also cut off the old connectors and re-crimped new connectors on all connections, then sealed them with adhesive lined heat shrink tubing. Some of the old connections were starting to look pretty old, and most had not been heat shrunk so it was time to replace the old connectors anyway.
To give you a better idea of where this bulkhead is, that is the rudder post sticking up behind the negative bus bar. It is about 16 inches to port from the plywood panels.
EDIT, Here is a old picture of the cockpit pre bimini (actually from before I even owned the boat), I circled the bulkhead that the panel is installed inside of, in red.