Luckily, I cam across a Hummingbird 798 SI combo the other day. I made an offer one it, it was accepted, and I picked it up that night. I was eager to install it the next day. The install takes about 2 hours.
The tools you will need:
- power screw driver
- box of machine screws
- wire strippers
- wire nuts/crimps
- heat shrink
- variety of drill bits
- wire ties
- latex gloves
- Dremel Tool
- First things first, I had to remove the old unit, it's mount, and it's wiring. Make sure you clean the surface that was below the old unit. Doing so will help prevent scratches from dirt particles underneath the new unit.
- Here is Tip #1. Any time you uncover old screw holes in fiberglass, make sure you make an attempt to seal them with silicone. You do not want water inclusion into the fiberglass.
- Locate the optimum position to mount your unit. Remember the old saying about measuring twice. Make sure that you sit exactly they way you will sit in the boat. Mark this location and the mounting holes with a Sharpy.
- Then, utilizing several of the same holes, I installed the Ram mount and antennae that came with my purchase. For the remaining holes, I used a pilot drill to make a small hole. This will prevent a direct screw installation from splintering the fiberglass. Like in the above Tip, make every attempt to seal up new screw holes by dabbing a little silicone on the screw you are about to install. I also rubbed a thin layer of silicon on the bottom of the mounts so that they would not rub and scratch the surface. It will also prevent water inclusion under the metal mount so that rusting of the mount is not possible.
- I then ran the wiring. There was already a good routing job done for the old unit. The horn cover had been slightly cut to allow passage of the wires. Since there were now 3 wires instead of 1, I had to Dremel the slot a little bigger. I used the same power and ground leads from the old unit. I used crimp connectors, but added heat shrink tubing in order to seal the wiring against water. The transducer wire is run to the back of the boat. In this case, I removed the cup holder and the driver side storage compartment basket. I then opened the cowl to and ran the wiring around the gas tanks, then ran it out of the hydraulic steering line ports and down the jack plate.
- Next, I modified the transducer holder so that I could bolt it to an existing hole on the jackplate. This simply involved locating a mounting position and drilling holes in the mount that would accommodate the mounting location. I made sure that the transducer was level to the water and very secure. It is imperative that you install it so that it is even with the bottom of the boat and there will be no part of the boat that will interfere with the ultrasonic signal.
- I then mounted the unit on the ram mount and plugged in the wire bundles
- That is the basic installation. It is not hard. I then cleaned up the installation by zip tying wires so that they would not be unsightly or loose.
Picture 1: The Uld Unit
Picture 2: Ram Mount Installed and Wiring Routed
Picture 3: Transducer Mounted
Picture 4: The Finished Project