They also act as both a powerful loudspeaker and a precise microphone that transmits the signals from the probe to the water and allows you to hear the return echo from the bottom and other submerged lenses.
Most transducers need to be in direct contact with water to function; they are usually installed in a mounting hole in the hull, in stern support below the waterline or externally in a dedicated box in the keel or hull. Stable fiberglass hulls also allow the use of an internal tank mount or “through-hull” transducers, which are mounted on the inner surface of the shell and send the signals from the probe directly to the water. You can read our how to mount a transducer on an aluminum boat to know more about it.
The type of hull on the boat will determine the kinds of transducer mounting available. To select the appropriate type of mounting, it is necessary to find the balance between the performance of the transducer and the boat, and the cost and complexity of the installation. You can also read our reliable oututboard motor buying guide to choose the best motor for your boat.
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Types of Transducers
Thru-hull transducer with the inclined element
These transducers are installed through a drilled hole in the fiberglass, metal or wooden hulls with the flush mounting against the outer surface of the hull. In this assembly, the active elements of the translator are permanently inclined to coincide with the angle of the helmet and ensure that the beams of the probe are directed downwards.
The design of the recessed mounting of these transducers allows a smoother flow of water on the hull, which supposes a reduced drag and a minimum repercussion in the performance of the boat. However, this type of transducers with inclined elements can see reduced performance due to external factors.
Thru-hull transducer with gondola
This type of transducers is installed on a rod that goes through a hole drilled in the fiberglass, metal or wood hull. The transducer protrudes from the surface of the hull, fixed on a nacelle that adapts to the angle of the hull and allows a flow of water as smooth as possible.
The through-hull transducers with gondola often offer the most reliable and accurate probe performance. However, the drag caused by the protruding transducer can affect the speed of the boat, as well as fuel efficiency.
The stainless steel transducers are recommended for metal helmets, while the bronze ones are recommended for wooden masks and any of them can be used in a fiberglass hull.
The aft mounting transducers are affixed to the stern of the boat, through which the flow of water flows smoothly. This type of assembly offers more straightforward installation and maintenance, without the need to drill holes under the waterline. Besides, when installed on a support, the transducer can be easily adjusted to compensate for the angle of the stern; Many supports also allow folding and clearing the transducer to tow it safely.
Designed for small outboard and other outboard and outboard vessels, these transducers are suitable for glider hulls. Transports with stern support also offer high reliability with minimal impact on the performance of the boat if they are installed in the proper location.
This type of transducers is installed in a small box attached to the outside of the boat, with the active side and the sides of the transducer in contact with the water. To install it, it is necessary to drill a small hole in the helmet to be able to introduce the transducer cable through a rod or a stuffing box tube.
Used more frequently in commercial offshore vessels, this type of external assembly is the one that most affects performance and is unsuitable for high-speed motorboats.
These transducers are installed in a small custom box on the hull or keel of the boat, aligned with the surface. Although it is possible to install them later, these transducers are usually mounted on ships with a box supplied by the manufacturer.
They also provide reliable and accurate probe performance, with little impact on the speed and fuel efficiency of the vessel. The performance of the probe and impact on the boat is comparable to that of the transductor para cascos with nacelle, a common alternative.
Assembly in the internal tank
Only suitable for stable fiberglass hulls, internal mounting transducers do not require drilling a hole to install them. In these cases, the transducer is mounted in a tank full of liquid coupled to the inner surface of the hull of the vessel and transmits the probe signals through the hull, without coming into direct contact with the water. Also, they are ideal for boats with trailers since they do not have external parts that can be damaged during towing, lowering or mooring. You should know how to clean a boat fuel tank without removing it.
The assembly in an internal tank does not entail an additional drag, so it does not affect the speed or fuel efficiency of the boat. Besides, it provides reliable probe performance at high rates, since water does not always flow over the transducer. However, the transmission and reception through the hull limit the maximum depth of the probe, as well as the capacity for the location of fishing, in comparison with the facilities in the water, under the waterline or inside the hull.