DIY Marine Electronics – Installing a Fishfinder

A big factor in buying a fishfinder is deciding whether to install it yourself or pay someone to do it for you. If you have never installed a fishfinder before this article will give you an overview of the general process. It is not intended to be a step by step guide for any particular fishfinder but it will give you an idea of whether or not you have the right skills to tackle the installation yourself.

Getting Started:

You can purchase fishfinder installation kits or assemble the components yourself using off the shelf products. The kit usually comes with some or all of the following components:

  • A rubber grommet or water seal (for feeding the wiring from the transducer to the fishfinder display unit)
  • Some extra wire
  • A waterproof battery pack and battery pack bag
  • A foam block (for mounting the transducer in the boat)
  • A heavy duty marine sealant such as Marine Goop or Lexel

Your fishfinder unit may or may not come with an installation kit, but at the very minimum should contain:

  • Fishfinder display unit
  • A ram mount and mounting bracket (to attach the fishfinder display unit to the boat)
  • Transducer and power cable

1. Mounting the Fishfinder Display unit

Determine where you will mount the fishfinder. Choose a location that makes it easy to reach while navigating the boat, and out of the way of any obstructions. Some installation mounts have back brackets which must be screwed on for stability. This type of mount requires you have access to the part of the boat underneath the mount so you can tighten the screws. You will need to drill holes for the mount and attach it securely. You can then insert the ram mount and fishfinder unit.

2. Installing the fishfinder transducer

There is more than one way to do this and it depends on your preference and on the type of fishfinder you purchased. Mounting a transducer inside the bottom of the boat involves cutting out a hole in a foam block designed to cushion the transducer. You attach the foam block using a good quality sealant and then insert the transducer in the foam block. The sealant must be applied carefully avoiding gaps and bubbles for the transducer to work correctly. An outside mount may require drilling a hole in the boat. You can use a rubber grommet or a waterseal and plenty of sealant to make the hole watertight. Alternatively you can mount the transducer on the the hull, at a point high enough to be in the water but out of the way of rocks or obstacles.

3. Wiring up the Fishfinder to the Transducer.

This step involves routing the power cable from the transducer to the fish finder display unit and may involve drilling another hole to keep the installation neat and tidy. Again, a grommet or waterseal may be needed.

4. The last step is wiring up the unit to the battery pack.

You may need to add additional lengths of wire depending on where you plan to stash the battery pack, the size of your boat etc. The batteries must be sealed in a waterproof container, such as a waterproof battery pack bag.

These are the basic steps required for installing a fishfinder. After you follow the four steps above, you can tidy up any loose wires with tie wraps and tuck them out of site. If you are handy with a drill and pair of wire crimpers it is easy enough to do but if the idea of drilling holes in your boat and crimping battery wires doesn’t thrill you it is well worth paying someone to install your fishfinder for you.