Transducers are used in fish finders and depth sounders to offer information about the depth of the water, the location of fish, and the structure of the bottom of the waterway. With their diverse abilities, they remain a key piece in ensuring proper nautical navigation and safety for the fishing community.
However, selecting the ideal location to put a transducer is trickier than most people think because each location has its own set of benefits and drawbacks. In this article, we will introduce the most well-known mounting locations for transducers, along with their placement considerations.
So take your time and keep reading!
The transducer is the heart of the fishfinder system, as it converts electrical pulses into sound waves or acoustic energy and back again. It sends out sound waves and waits for the echoes so that the fishfinder can interpret what is beneath the water’s surface.
All in all, the top four transducer types include:
- Transom-mount (TM)
- In-hull mount (IH)
- Thru-hull single (TH) or thru-hull pair (THP)
- Trolling motor mount
Where To Mount A Transducer On A Boat?
1. Placement Considerations for Transom-Mount Transducers
Transom-Mount Transducer Overview
A transom-mount transducer is a sonar device that is typically mounted on the transom or back of the boat for user-friendly installation and removal. It can work effectively with any hull material, as long as it is kept in constant contact with the water.
This type of transducer is well-suited for trailered boats, especially when used with a folding bracket. Still, the transom-mount type is not recommended for use with sailboats due to excessive heeling or vessels with stepped hulls.
For installation, choose a location where there is the least amount of turbulence and bubbles and where the water flows as smoothly as possible. The transducer must be submerged in the water at all times, and the keel or propeller shaft must not be in the way of the sounder beam.
One more thing, check to make sure that there is enough headroom and a minimal deadrise angle. In terms of placement considerations for the transom-mount transducer, the waterline, engines, propeller, and hull should all be taken into account.
Vessel Waterline and Your Transom-Mount Transducer
The waterline of the vessel comes first as an essential placement consideration. It is the level at which the vessel sits in the water. When the ship is loaded with a combination of people, fuel, and equipment, the hull below the waterline is submerged.
In fact, the vessel’s waterline may change, for instance, by adding, reducing, or redistributing weight on the vessel. So when the boat is either moving or still, you can mark a potential mounting position on the hull using a grease marker or waterproof tape and then observe the waterline fluctuations.
However, keep in mind that your transom-mount transducer should be placed parallel to the waterline. Moreover, the gadget should extend into the water while the boat is in motion at a depth of 10 mm below an aluminum hull or 3.5 mm below a fiberglass hull.
Propulsion and Your Transom-Mount Transducer
In general, turbulence is generated by the engine and propeller at the stern, or, in other words, near the transom-mount transducer. In order to avoid this turbulence-related interference as much as possible, there are some placement recommendations for you.
Firstly, when mounting a transducer on a boat with an outboard or inboard/outboard motor, keep it as near to the transom’s centerline as you can, but keep it at bay from the propeller (such as at least 38 cm).
In cases where the propeller turns clockwise, putting the transducer on the starboard side of the boat usually produces the best results. And on the contrary, if the propeller revolves counterclockwise, you should mount the transducer on the port side.
If your boat is a single-drive boat, you shouldn’t mount the transducer in the propeller’s path because the turbulence and cavitation that result from doing so could harm the propeller. Nevertheless, if it is a twin-drive boat, simply put the transducer between the drives.
Hull Features and Your Transom-Mount Transducer
Another thing that can affect your transom-mount transducer is the hull features that generate turbulence. Therefore, commonly, you should place your transducer near the centerline of the boat if you intend to use it while traveling at greater speeds.
Moreover, avoid placing the gadget on the transom behind or close to the propeller, trakes, rivets, ribs, or any parts of the hull that stir up the water and produce air bubbles.
In addition, turbulence is also produced by fittings and water intake or discharge ports. For that reason, if you have to attach the transducer aft of a thru-hull fitting, then mount it at least 4 feet (1.2 m) away from the fitting.
2. Placement Considerations for In-Hull Transducers
In-Hull Transducer Overview
Unlike the transom-mount transducer, the in-hull mount transducer is mounted to the hull’s inside floor, which means it does not require a hole through the vessel. Anyway, due to its placement, the in-hull transducer will send signals from within the vessel, and that may weaken the signal.
Regardless of that, the in-hull mount claims its power as it can work effectively at high speeds when installed away from turbulence. One more benefit is that it can be installed while the vessel is still in the water.
Also, in-hull models do not include a temperature or speed sensor; therefore, these sensors must be installed externally on the transom if needed.
After all, consider your boat when using this transducer, as it is suggested for solid fiberglass hulls that are up to 0.75 inches thick. Alternative metal, wood, or cored-hull boats are not good options at all.
When operating, a properly positioned in-hull transducer will deliver outstanding performance when searching for fish and other bottom features, with only a slight loss in range at the transducer’s maximum depth.
Hull Features and Your In-Hull Transducer
As fiberglass has sonar characteristics similar to those of water, the in-hull transducer can transmit and receive sonar signals through it, removing the requirement to drill holes in the hull.
Commonly, boat owners who want a transducer that is hidden inside and doesn’t require drilling holes in the boat’s hull opt for in-hull mount transducers. Regarding the hull of your sailboat, you should abide by the following instructions for the best results:
- As mentioned earlier, the transducer must be mounted on a solid fiberglass, and it will not function in metal, wood, or cored fiberglass hulls. When installing, you can mount your transducer near the keel if it does not block the signal or create an echo.
- Place an in-hull model as flatly as possible in the bilge near the transom on single-thickness fiberglass hulls; the bilge is the lowest part inside the hull.
- The angle between a horizontal line and the outer hull at a single point is called the deadrise angle. For an in-hull type, it varies from 0 to 25 degrees based on each model.
- Bear in mind that the transducer should not be mounted over hull features that thicken the hull beneath the device or over fittings, water intake ports, or discharge ports that stir up the water.
3. Placement Considerations for Thru-Hull Transducers
Thru-Hull Single or Thru-Hull Pair Overview
The thru-hull transducer is the type of model that requires installation through a hole in the hull. It can work well with any engine type and deliver excellent overall signal quality, even at high speeds and greater depths.
Aside from that, for optimum performance, the transducer has to be in direct, unhindered contact with smooth water. This is the type that is least vulnerable to turbulence damage but can still be impacted by turbulence below the hull. There are two types of thru-hull transducers: external and flush.
External Thru-Hull Type
An external thru-hull type extends beyond the hull’s outer surface. For installation, the ideal spot is parallel to the waterline. Depending on the placement area, you may or may not need a fairing block.
On the one hand, a fairing block allows you to place the gadget parallel to the waterline when mounted on a section of the hull with a higher deadrise angle. And on the other hand, if the transducer is mounted on a flatter area of the hull, the block is not required.
Flush Thru-Hull Type
In comparison to external types, the flush thru-hull, as mentioned in its name, sits flat against the hull and generates less drag. And without a fairing block, a tilt flush thru-hull type can be installed on an angled surface.
Propulsion and Your Thru-Hull Transducer
Similar to transom-mount transducers, the turbulence generated by the propulsion system when the boat is in motion may affect the function of the thru-hull model. Therefore, the perfect position for a thru-hull type is in the bilge near the keel and transom, as the water there is the smoothest while the vessel is moving.
It is recommended to mount the transducer near and in front of the engines on outboard and sterndrive vessels while on inboard vessels, it should be installed in front of and far away from the engine propeller and shaft.
In terms of single-drive boats, the device should not be placed in the propeller’s path. And for the twin-drive boats, consider putting the transducer between the drives if possible.
Hull Features and Your Thru-Hull Transducer
The placement of the thru-hull transducer varies depending on the type of vessel. Simply be mindful of mounting the device parallel to the vessel’s bow-stern axis and stay away from areas aft of hull features that agitate the water, for instance, strakes, struts, fittings, or water intake or discharge ports.
Also, two thru-hull transducers must be placed on either side of the keel on hulls with a deadrise of more than 5 degrees. Regarding that, you should choose a suitable transducer for the hull deadrise angle to ensure that the sonar beam rests at a 90-degree angle to the bottom. Fairing blocks can be used if needed.
Where to mount a transducer on a trolling motor?
There is a wide range of transducers that you can mount on a trolling motor, such as down imaging, side imaging, and forward-facing transducers. And the best place to mount them depends on the type of device you are choosing.
They are typically forward-facing transducers (such as LiveScope, Active Target, or MEGA Live), which are mounted on the shaft of the trolling motor since this allows these transducers to have an unhindered view in the forward direction.
When mounted, your transducer will automatically point in the same general direction as the trolling motor. However, if the transducer (for instance, a 2D or down imaging transducer) is mounted on the side of the bottom compartment, you can also accomplish this using a trolling motor barrel mount.
This mounting position allows the transducer to be pointed downward without blocking its field of view.
The best locations to mount different types of transducers
Where to mount a side imaging transducer?
The side imaging transducer is well-suited to mount on the transom, as it generally allows the sonar beams to shoot sideways in both directions while you’re maneuvering the boat. By doing so, you will be able to explore wide regions of water on both sides without having to slow down.
Comparable to a transom-mount transducer, you must place the side imaging one parallel to the waterline for the side beam to be displayed accurately.
Where to mount a down imaging transducer?
When it comes to down imaging transducers, the well-suited position is either the trolling motor or the transom, depending on your intention.
The ideal option for mounting a transducer on your trolling motor is a barrel mount since it enables you to place it at the very bottom and aim it downward with an unobstructed view.
Where to mount a LiveScope transducer?
A forward-facing sonar, such as a LiveScope transducer, is typically mounted on the shaft of the trolling motor.
Alternatively, a transducer mounting pole is a potential option. You can attach it to the front of your boat similarly to a trolling motor, as it was initially designed for live sonar. This will be so inconvenient that you only need to simply move the mounting pole’s handle to have your transducer point in various directions.
Where to mount a transducer on a pontoon boat?
The pontoon boats are constructed on top of pontoon tubes rather than having a transom like other boat types. Due to this reason, they have a distinct spot to mount a transducer.
The finest spot to put a transducer is at the bottom edge of the bracket at the back end of one of the pontoon tubes. When mounting, put your transducer just under the waterline while keeping it parallel to the water’s surface.
By far, proper installation and use of a transducer can give you more chances when fishing. At this point, we hope that we have introduced the most fundamental knowledge about the major types of transducers for your fishing plan. Stay tuned and be up-to-date with our new blog for any new information. See you next time!
Born in Lakeland, Florida, Daniel has started fishing since he was just a tiny little kid. His father was a real good fisherman, as he taught Daniel tricks and tips to catch the fish better. From those childhood memories, Daniel has built up his love for fishing. Until now, he has been participating in several bass tournaments and currently serves as the Chief Editor of fishingonsunday.com to share his precious knowledge and experiences with many more people.