My prime consideration was to have it where it would have a clear view of the sky. That meant it could not be mounted near the console or the motor. The configuration of the console eliminated the possibility of mounting it at the console on an antenna extension as I did on my Z-7. One of my fishing buddies was always teasing me about having the puck mounted on the two foot mast. In my defense, there is a reason that Humminbird provides a threaded flange which can be bolted to the puck to do just that.
I settled on installing it at the bow, on the panel for flush mounted sonars. The problem is that the surface is angled so the sonar will face the bow angler. My solution was to make a disc out of black gel coat impregnated with small pieces of mat torn from scraps. Fortunately, the cups I use for spraying gel coat were the perfect size. Poured just over an inch of black gel coat in the cup and catalyzed it. Then the small pieces of shredded mat were pushed into the gel coat with a paint stirring stick, and pushed around until the mat was thoroughly distributed in the gel coat.
Once cured, the cup was peeled away, and what remained was removed using a belt sander clamped to a table top.
The boat was levelled using a long level on the front platform. Boats rarely sit level on the water. They may list or sit down by the bow or stern. Since a boat is dynamic, and not static, it is not necessary to be absolutely precise when tapering the disc to make its top level. I used a short mason's level, and as long as the bubble was between the lines it was good enough.
After the disc was tapered to be level, it was hand sanded, including hand sanding a radius on the top edge. A hole was drilled in the center, and the two mounting holes were drilled. The threaded flange that came with the unit was used to drill the two mounting holes. Here you need to pay attention. The mounting holes on the puck are at each end of the HUMMINBIRD name. For a neat install, keep that in mind before you indiscriminately drill the holes. The thin edge of the disc will be toward the bow, the thick edge toward the stern. The holes should be at the sides of the disc.
Once finished, the puck got sprayed with flat black prior to final installation. For installation, a small bead of black silicone was applied near the edge of the bottom surface. The puck was then set in place using bolts to get it in proper alignment. Just enough pressure was used to cause the silicone to bulge out at the edge of the disc. It was then allowed to set up before finally bolting the entire assembly together. Because the silicone is glossy, I got an artists brush, sprayed some flat black onto a piece of cardboard , then painted over the glossy black.
Three angles of the "trial fit".
The finished install.
To layout the components that mount on the fiberglass surfaces, I covered those areas with masking tape. It allows parts to be moved around without damaging the gel coat, and can be marked when the final location is determined.
Some hints about drilling through the gel coat. Use a small drill to make the initial hole. Then, use a countersink bit. Countersink the hole until the diameter of the countersink is just a tad larger than the hole you intend to drill. It will eliminate the problem of gel coat chipping and fracturing that will otherwise inevitably be caused by twist drills.
For the larger holes, use the paddle type bits that have a spur on each edge. That spur will cut through the gel coat without fracturing it. The masking tape will also help in that regard, though by itself it will not prevent the chipping of the gel coat.
Here's my finished project.
