Outnabout,
This wasn't a really difficult project, just very time consuming. Unfortunately, I don't have a lot of time at the moment with work and some family medical issues. Another thing is, the hole sizes for your instruments. It was much easier for me to cut those holes before I epoxied the wings on.
As you asked in the board mail, Makrolon/Lexan/polycarbonate was hard to find in small quantities. A big panel of the stuff is very expensive (to me at least). I ordered my 1' X 2' X .375" piece from Interstate Plastics off the internet. It was grey, because that was the only piece of .375" they had available, and I spray painted the back of the finished panel black so that it looks black (and it's shiney) from the front. The piece cost $15, plus $15 small order fee and $15 shipping. You might be able to go way cheaper if you have a big custom glass/plastic shop nearby. I bought the epoxy in a tube from Lowe's. It has to be specifically for bonding Lexan/polycarbonates. The polycarbonate comes with sticky paper on both sides. Leave that on the piece for as long as you can to protect it from scratching. The good thing about this stuff is that it is very easy to cut with a saw and router, and to drill. I worried about that, because in the past cutting other types of plastic, the plastic would remelt back together from the heat of the saw blade. This stuff cuts like Starboard, maybe better.
The front panel is trapezoid shaped, 20 5/8" at the top, 23 3/4" on the bottom, 9" high, and the inside angles of the sides at the bottom is 79 degrees. The bottom edge is cut on an angle so that when tilted back in its finished position, the bottom edge lays flat in the tray in front of the instrument box. Because of the lip in the tray right in front of the compass, you cannot bring the bottom edge of the Makrolon too far out or it will not clear the top of the tray as you tilt the finished door panel up to access the instrument box.
After the front panel was cut, I got a stainless steel piano hinge, cut to size with a sawzall and sharp edges buffed with a grinder, and routered out a recess at the top inside edge of the door panel for the hinge to fit in. Don't place the hinge too far down because when you attach the door to the fiberglass enclosure, the top edge of the door panel might impact the top of the fiberglass enclosure frame behind it restricting how high you can raise the door panel. I used small countersunk flatheaded screws to attach the hinge to the door panel and the hinge to the fiberglass enclosure frame. On the frame, you will have nylock nuts inside the instrument panel so that on the door side you have the flatbolt head side. On the door side of the hinge, the countersunk bolt head will obviously be exposed on the outside of the door panel (it will be flush with the face of the door panel if countersunk correctly--before final installation you will spray paint the bolt heads black to match the door panel color). On the inside, you will need to use the flattest nut you can find (can't use nylock nuts, they're to tall), and saw off the remaining stem of the bolt, so that you have enough relief to close the door panel without the bolt causing a hangup on the other side of the hinge. On the bolts I used to attach the hinge to the frame, I used long enough bolts so I could attach plastic zip fasteners and add another nut on top of that to use to hold the wire cables from the units mounted on the door. Once you test mount the door panel you can decide the location for the spring to hold the door in the desired open position. Just make sure wherever you place the spring mount, that you give clearance for the right edge of the unit mounted in the door panel.
The little "wings" that close in the sides of the new instrument panel door are a little more difficult to craft. With the front panel layed into position, I measured the angles at the base of the door panel and at the top from the door frame to the tilted door with a protractor-like device. Then cut the pieces. I had a desktop belt sander set up on a table in the boat and I rounded off the back lower corner and adjusted the back and lower sides till the wings dry fit good. To get a good dry fit at the bottom edge of the wings, the bottom edges also have to be beveled because the wings fit at an angle on the front panel.
Straight cuts, and beveled edge of the front panel, were done with a table saw using a small toothed carbon tipped blade. The holes for the two GPS's were made by tracing out the hole sizes onto the paper covered Makrolon, then using an appropriate sized hole saw drill bit for the corners. The interior straight edges were cut with a coping saw (take the blade off the saw and reassemble the saw with the blade inside one of the drilled holes). I didn't want to cut the straight edges of the instrument holes with a jig saw because the foot of the jig saw could mar the plastic surface of the panel.
At this point I used a rotary sander with fine paper to smooth the edges of the door panel. If you cut the panel with a nice sharp table saw blade this doesn't take too much effort. I then used a wet 600 and 800 paper to polish the edges of the front panel. It should turn out pretty close to mirror like. I used a finer window polish then to get a mirror finish on the edges.
Now you can glue the wings to the front door panel (on the underside of the door). Use a polycarbonate glue. I scrapped excess glue on the inside of the door panel, because then you will probably want to glue on filet strips of leftover Makrolon to give a larger bonded surface to the wings on the inside of the door. Any glue that oozes out on the visible side of the door panel I carefully scrapped up with an exacto blade. After the door sets up, hopefully you didn't let much epoxy ooze out on the outside of the bonding surface. If so, you can carefully cut with a sharp blade and repolish.
Take your door panel with wings out to the boat and see how it fits. You will probably need your desktop belt sander to make final adjustments to the door so that it fits snuggly. When it all looks good, and wing edges are polished to your liking, Reassemble hinge and instruments, sit back and finish the last of your 3 cases of beer. If you have bought a grey Makrolon panel, you will now paint the inside. Remove the hinge, tape the outside "show" surfaces of the door panel and spray paint the inside of the panel a gloss black. After it dries reassemble and you are done.
