The past few days have demonstrated to me how "non-standard" anything marine is, to a very frustrating and time-consuming level. I'm still a bit in shock. First, went to mount my Simrad HS60 GPS compass. It comes with a bracket that allows it to be mounted to an antenna base. However, the back of the bracket has a slot and large hole (1st photo). The antenna base will be open to the inside of the boat where the cable is routed. There is now way to seal this hole. It faces aft, yet I know way too much about wind-blown rain and snow, and feel strongly that water would fairly easily find its way in there. I could have put some gorilla tape over it, but it's very against my grain to start band-aiding things together on a new build. So I researched more and came to a dead end. I don't want to mount it flat to the roof because it looks goofy and for other reasons. So I finally tossed in the towel, drew a sketch, and sent it to my friend who runs a metal fab shop (2nd photo). I'll have the custom mount early next week, tilted at the perfect angle, so several problems are solved at once. Powder-coated white it will look nice next to the radar mount. Good grief!
Next up was VHF and AIS antenna mounts. Should be pretty straight-forward, yes? Well, I like to use acorn nuts rather than normal nuts when exposed inside the cabin, so that means you get to cut all the bolts to juuuust the right length. So I did that, and the front worked out pretty well, but for some reason the roof thickness varied by 3/8" between mount positions (!?) so I got to cut 4 of the bolts twice. Plus when I torqued them down the foam compressed on top and the 1/4" interior skin gave a hair, so I got to cut all 8 bolts one last time. Good grief!
Now the fun part. I screw the antenna down, and when it bottoms out on the mount, the cable stuck out at exactly the wrong spot - gets in the way of the handle both up and down. So I stole the 1" lock nut from the GPS compass mount and used that as a jam nut for the AIS antenna mount. The VHF mount I just wrapped the cable around the backside and that worked out good enough. Seems like they should come with a 1" jam nut or a set screw....and I almost drilled and tapped for a set screw but I decided against it.
Next I tried 2 brands of cable seals. Blue Sea, which is typically top shelf, requires you to drill your own hole through the rubber grommet. This is difficult to do well (I know from other experiences drilling holes through rubber), plus they are bulky, so I returned those. ScanStrut makes a nice one, but their hole size that fits VHS cable is just a hair too loose. So I had to wrap the cable with self-sealing silicone tape where it passes through the gland (photo 4). That worked well.
So the photos show the saga. I always like to countersink any holes in fiberglass before bedding any equipment (photo 3) - it helps avoid spider cracks and gives the sealant a good place to bed. I also bed the head of any bolts in sealant so water doesn't migrate down the bolt shaft and weep into the cabin (photo 4).
