I3: In-dash Instrument Install

Top-of-the-dash instruments move in-dash, relieving clutter and delivering new capabilities.

If you’re like me, you’ve owned a string of used boats over the years, and they always come equipped as the previous owner desired. Sometimes those features fit your needs, sometimes not. My latest acquisition came with a compass and a fishfinder mounted on top of the dash. It’s important to have a compass, but I don’t fish in this boat, and the instruments’ location made cleaning the windshield a pain. The space seemed like it could be better utilized, especially since none of the instruments in the dashboard worked. It occurred to me that I could free up some space on top of the dash by replacing the instruments with in-dash ones.

DIY in-dash instrument instructions

Depending on how your dash is configured, removing the steering wheel may be necessary. To do that, pry off the center cap and use a socket wrench to loosen the nut that holds the wheel onto the shaft. Since it’s likely to be stuck in place, it will require some force. Loosen the nut until the outer face of the nut is flush with the top of the shaft. Pull the steering wheel toward you while tapping the nut and shaft with a hammer (a little penetrating oil isn’t a bad idea). A third hand is useful, so one person can pull on the wheel evenly while the other taps the shaft with the hammer. Be patient, taking care not to damage the nut or shaft, and the wheel will come off. If yours is particularly stubborn, you may have to use a gear puller, but the pull-and-pound method works most of the time. The wheel is aligned to the shaft with a Woodruff key that rests in slots in the wheel and the shaft. It’s small and easy to lose, so put it somewhere where you can find it at reassembly time.

Next, remove the instruments from the holes you want to reuse. Disconnect the battery, so the panel isn’t live. You can either loosen the dash panel from the console and pull it away enough to access the back of the instruments, or you can lie on your back and remove the instruments from behind or beneath. The instruments are usually held in place with a plastic or metal bracket that snugs them into the hole. Remove the wires connected to each instrument and bracket, and then remove the instrument from the hole. Pay attention to the wires as you remove them, because you may need to reconnect them to each other to keep other instruments in the dash functioning. They usually have lug (round hole) or spade (Y) terminals on the ends, which you can replace with male/female or butt crimp connectors, so you can attach them to each other. If you’re in a saltwater environment, or even in fresh water, earn extra quality points by coating the finished connection with liquid tape, to lessen corrosion. If you don’t need to connect the unused wires that you took off the instruments, remove them or tape/coat the ends to insulate them, so you don’t have bare live wires under the dash.

DIY in-dash instrument instructions

With holes empty and wires stowed, see if/how the new instruments fit in the holes. If you’re lucky, they’ll pop right in. If you’re like the rest of us, they won’t. In my case, it was 50/50. The depth gauge fit perfectly in the hole vacated by the ammeter. The compass, however, was a little smaller than the hole the tach was in, so I made a trim ring out of some Lexan. You could also use quarter-inch plywood. A little spray paint, and you’re in business. The compass instructions say it can be used on a dash angle of up 45 degrees, but I didn’t like the way it looked mounted in the dash with the trim ring, with the boat set as it sits in the water, since the card was nowhere near parallel with the housing. I made two identical shims of plywood, to tilt the trim ring out at the bottom and get an angle that looked better. One shim went behind the bottom of the trim ring, on the face of the dash, and the other went on the top of the threaded barrel of the compass, behind the dash, so the nut that holds the compass in place bears against it. The compass looks more to my liking, with the card almost parallel with the housing. The installation put the compass very near the steering rack, which caused a deviation in the compass of about 7 degrees, but it came with instructions and a tool for correcting this.

Next, mount the transducer for the depthfinder, following the directions that come with it. (I know, real men don’t read directions, but men who only want to do a job once do.) Fish the wire up to the dash, hiding and securing it neatly, and connect it to the depthfinder. Then, wire the instruments, reconnect the battery, and test the new instruments — and the other instruments in the dash, if applicable — to see if you did it right. I wired the compass light to the nav light circuit, so it comes on when the nav lights are turned on. I wired the depthfinder to the anchor light switch, which was unused, to minimize dashboard clutter. If you have to, you can install new switches. Finally, reinstall the steering wheel, dabbing a little anti-seize lubricant on the shaft, to make future wheel removal easier.

I filled the holes left by the previous instruments in the top of the dash with silicon, and I will patch them with some vinyl repair goop. If I ever get crazy and tear the whole console apart, I’ll reupholster it so the next owner will have a nice clean surface to drill holes in when he wants to equip the boat the way he wants it…

DIY in-dash instrument instructions

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