Topic 15 - Mounting A Transducer

The transducer is mounted so that the oscillating elements inside are vertical to the waterline. There are four common ways to mount a fish finder transducer;

The different ways listed here all have their unique advantages and disadvantages, with the ideal mount being the first, Through Hull. This mount consists of carefully cutting a hole in the bottom of the boat and fitting the transducer inside, so that it is in direct contact with the water. Since the transducer is mounted through the hull, the ultrasonic pulse waves and returning echoes are very clear. However, the caveat is that you need to cut a hole through the hull, which is something that deters a lot of boat owners.

This brings us to the next way of mounting transducers, In-Hull or Shoot-Through mount.
In-Hull mounting means that the transducer is mounted against the hull of the ship, fastened with silicon in a special case. This case is later filled with a type of oil to make sure that the transducer is in full contact with the hull. It is very important to choose a proper mounting location, otherwise air turbulence from below the vessel might cause interference.

The downsides with In-Hull mounting is that first of all, it does not work with vessels that have hulls made of aluminum, wood, steel or any material that absorbs a lot of the ultrasonic pulse waves. Secondly, since the signals are transmitted through the hull, a certain amount (20-50%) of the signal will get lost, resulting in lower performance and ability to detect fish. Thirdly, for those with fish finders sporting the “ACCU-FISH™” functionality, it is recommended to mount the transducer using Through-Hull or Transom mount.

If the bottom detection function of recent FURUNO Fish Finders want to be used, the transducer has to be mounted either through Transom mount or Through-Hull.

Transom mount is common in smaller boats, the transducer is mounted below the waterline at the transom. This way of mounting the transducer is popular due to its simplicity, but it also runs the risk of interference from aerated water originating from the propeller.

The fourth and final way to mount the transducer is side mount, which is an improvised way where the transducer is mounted on a long pole. During travel to and from fishing grounds, the pole is taken up from the water. The benefit here is that for boat owners who do not wish to make proper Through Hull installations, it offers good performance while being very simple.