Transducer Mounting Height on a Boat

Mounting your transducer at the ideal height will significantly improve your device’s accuracy and performance. However, finding the right height is more complex than most people think.

There are many types of transducers, and they all come with different mounting styles and heights. Each site has its own set of benefits and challenges.

This article provides a guide to transducer mounting heights on a boat. It will help you choose the correct location and height to mount your device for optimal performance.

Types of Transducers

There are four types of transducers classified according to mounting style and location. They include:

  • Transom mount transducer
  • In-hull mount transducer
  • Thru-hull mount transducer
  • Trolling motor transducer

These transducers require to be mounted at a certain height to work efficiently. Unfortunately, most anglers install their transducer in the wrong place, and as a result, they experience inaccurate sonar imaging. Luckily, this article covers where to mount each of them. Let’s take a closer look.

Related Article: Best Fish Finder GPS Combo

Mounting Height for Transom Mount Transducers

Transom mount transducers are the most widely used sonar devices. They are easy to install and require no drilling. They are commonly installed with a mounting bracket on the boat’s transom [1].

The best place to mount the transducer is in an area that experiences less turbulence, usually 15 inches away from the propeller on the starboard side. If the device is too close to the propeller, the blades will bump into it and destroy it. They will also create a lot of turbulence, thus interfering with sonar feedback.

It is important to note that if your boat has two engines, the best location to install the transducer is between the two motors. Additionally, if your boat has a step hull, you can install the transducer on the step. Avoid placing the device on the transom behind the step since it will not be in contact with the water at high speeds.

Additionally, the transducer should be placed parallel to the waterline, with the lower part of the device sticking out 1/32 to 1/16 inches beyond the boat. If the device is too high, it will be ineffective when the boat is traveling at high speed.

Keep in mind that the water level at the transom goes down when the boat is moving at high speed. So if your device is too high, it will not be fully submerged in the water and will overheat. It will also stop functioning since it is impossible to transmit and receive sonar frequencies through the air.

On the other hand, if the device is too low, it will trigger turbulence which lowers the transducer’s performance. It will also trigger the formation of a rooster tail and air bubbles as the water flows over the device, resulting in poor sonar performance.

Transom Angle

Once you figure out where to place the transducer, the next step is to determine the transom angle. The standard angle is 13 degrees, but it can vary. Luckily transom mount kits include shims to help account for the difference. The transom angle should range from 3 to 20 degrees.

When installing, ensure that the device is level with the bottom of the boat or slightly below. The leading edge of the device should not exceed ⅛ of an inch below the ship. Additionally, the trailing edge of the device should be 1-3mm below the leading edge or bow to prevent aeration.

Thru-Hull Transducer Mounting Height

Mounting a thru-hull transducer involves drilling holes in the boat’s hull and fitting the device through the hole. Since the device is always in direct contact with water, it has more accurate readings and the best performance.

Install the device as close to the centerline as possible and at least 12 inches away from anything that causes turbulence, such as propellers. Also, ensure that the device is parallel to the waterline and flush with the boat [2].

If you are using a traditional thru-hull transducer, you will need a fairing block to ensure the device is properly aligned and secure. The transducer should be fully submerged in the water. It can be flush with the boat or slightly protruding, around ⅛ an inch beyond the hull.

Mounting Height In-hull Transducers

An in-hull transducer is usually mounted on the inside wall of the hull. It should be mounted only on fiberglass since this material has the same sonar qualities as the water. Therefore the transducer can transmit and receive sonar frequency without hindrance.

Try to install the device as close to the hull’s centerline as possible. The location should be far from strakes, the propellor, and other protrusions that create turbulence. In addition, the transducer should be on a flat surface with no foam in between the walls for the best depth range.

Most importantly, the device should be placed in an area that remains in contact with the water even when the boat travels at high speed.

Trolling Motor Transducer

This mounting style requires a puck-shaped or a skimmer transducer. Install the transducer to the motorhead between the propellor and the fin. The transducer should face straight down for more accurate findings. It should also be fully submerged when the boat is on the water; otherwise, the device might overheat and get damaged.

Testing the Transducer

Once you install the transducer, take it out into the water for testing. For accurate readings, the device should be parallel to the waterline. It should also be flush to the boat or 1/32 to 1/16 inches below the bottom of the vessel. If you get inaccurate readings, make sure you adjust the transducer to the correct height.

If the mounting height is too low, it will expose the device to turbulence and air bubbles, affecting sonar reading. And if it’s too high, it will pop out of the water when the boat is at high speeds. The device might end up overheating and damaging the piezoelectric crystals.

Also Read: How to Tell If a Transducer Is Bad

The Bottom Line

Transducers are a great way to keep track of the underwater environment. However, they need to be installed in the right location and ideal mounting height. Otherwise, they will not function as well as they should. This article is a general guide to transducer mounting height on a boat. You can use it to guide you in installing your transducer.

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