In mine I have a GPS, depth sounder and an Impulse Loran C / depth sounder combination.
In the bottom side I installed a courtesy light and a Shakespeare auxiliary speaker for the VHF radio.
To get the ball rolling, I first made a model of it from card board and masking tape. Be sure to make the face tall enough so that there it is at least 1/2" of wood above the openings for the electronics at the narrowest point. (Notice that it's made with the face on a slight down angle, this way the screens are facing me directly when I'm at the helm.) Holding the model where it was to be installed, I would mark where it needed trimming then take it back down and make the cuts. I then repeated this until the fit was good. The next step involved disassembling the model and using the pieces as a template to transfer the them onto 1/4" ply wood. Grooves had to be cut thru two of the three plies in the front edge of the bottom piece to bend it slightly upward. Epoxy was used to hold it in place. (see the bottom picture) After cutting the wood pieces, I then assembled them using West System resin and a light roving in the corners. I also added West System resin and a light roving across the areas where a hole would be drilled for mounting. Next the console was fit into place and filed to fit where necessary. The holes for the electronics were then cut out and the mounting holes were also drilled.
I wanted to keep installation simple. It needed to be easy for one person to put up and just as easy to remove for service. This was achieved by a trip to Home Depot where I picked up some small angle brackets. The one that screws into the roof required an extra bend but other that that, I used them as purchased. The ones that are attached to the upper front edge of the console are held in place with a screw and "T" nut on the opposite side. Four pairs of these were installed with two centered in the console and the other two in the top front corners to keep the unit from shifting side to side. The idea of these brackets is that I can lift the console up against the roof aft of the brackets, then slide the console forward and the tabs will lock together.
Once in place, a row of four screws holds the forward edge of the console to the roof.
Once I was happy with the fit it was now time to cover it. Since power sewing is not one of my talents, I had to figure out another way to do it. Using a spray adhesive I glued a layer of light foam padding on the outside. Next the console was covered with vinyl which was fastened on the inside with staples. Contact cement would have worked as well but staples were quicker. I also wanted something to trim off the top edge but didn't want to buy a whole roll of piping. Instead I used a piece of #10 gauge wire wrapped in vinyl and stapled it to the top edge.
Well, that's pretty much it in a nut shell. Keep in mind that this is not the only way to tackle this project. There can be several different ways to assemble, cover, mount and outfit these units. You simply have to choose what will work for you.
I would do that if I had a hard top.
