Transducers For Boats: Choosing The Best Fit

Transducers are an essential component of any fishfinding system, converting electrical pulses into sound waves to detect objects and the temperature of the water beneath the boat. When selecting a transducer, there are several factors to consider, including the type of boat, the mounting location, the transducer material, and the frequency. The type of boat and the material of its hull will determine the most suitable transducer material. For example, bronze transducers are ideal for wooden hulls as they resist the effects of wood expansion, while plastic transducers are suitable for fibreglass, steel, or alloy hulls. The mounting location depends on the hull design, with through-hull mounting providing the most efficient performance but requiring a hole to be cut in the bottom of the boat. In-hull transducers, on the other hand, are mounted internally and transmit signals through the hull, making them a less invasive option. Lastly, the transducer frequency should be chosen based on the fishing needs, with higher frequencies providing greater detail at shallower depths and lower frequencies offering greater depth penetration.

Transducer mounting options: in-hull, through-hull, and transom

When choosing a transducer, it's important to consider the mounting options available to you. There are three main ways to mount a transducer: in-hull, through-hull, and transom. The best option for you will depend on factors such as the type of boat you have, your hull material, and your personal preferences for installation and performance.

In-hull mounting involves installing the transducer inside the hull of the boat, against the bottom. This type of mounting is suitable for boats with a single-layer solid fiberglass hull. The transducer sends its signal through the hull, so there is no need to drill any holes. In-hull mounting is a good choice for trailered boats, vessels with stepped hulls, and other types of high-performance hull designs as it eliminates drag and the potential for fouling. It is also a relatively simple and inexpensive installation process. However, it is important to note that in-hull transducers cannot be used with cored hulls, such as those made with end-grain balsa or foam. Additionally, in-hull mounting may result in some power loss due to the signal passing through the hull.

Through-hull mounting, on the other hand, requires cutting a hole in the bottom of the boat and mounting the transducer flush with the bottom, so that it is in direct contact with the water. This type of mounting is considered the most efficient way to get the best performance out of a transducer. It provides the strongest signal and minimizes the impact of factors such as turbulence, bubbles, and motor noise. Through-hull mounting is suitable for boats with fiberglass, metal, or wooden hulls, and there are different types of transducers available depending on the hull material. For example, stainless steel transducers are recommended for metal hulls, while bronze transducers are a good choice for wooden hulls. However, through-hull mounting is more complex and may not be suitable for all hull designs.

Transom mounting is the simplest and quickest way to mount a transducer. It involves affixing the transducer to the stern of the boat, where smooth water flow is passing off the transom. This type of mounting is suitable for smaller boats with outboard or sterndrive motors, as well as boats that are trailered regularly. Transom-mounted transducers can be easily adjusted to compensate for the transom angle and are usually mounted to starboard to avoid interference from the propeller. While transom mounting may be less efficient than through-hull mounting, it can still provide effective performance if installed properly.

Transducer materials: bronze, plastic, and stainless steel

Transducers are made of either bronze, plastic, or stainless steel, each suiting a different kind of hull. The type of hull you have will determine the best transducer material for your boat.

A bronze transducer is perfect for a wooden hull as it is built to endure and resist the effects of wood expansion. Bronze is a long-lasting material that is well-suited for the marine environment. It is also utilized in many other underwater boat fixtures. However, bronze transducers are not recommended for use on any boat with a metal hull to prevent electrolytic corrosion. The interaction between the metal hull and the bronze transducer, especially in saltwater, will eat away at the metal hull and/or the bronze housing.

Plastic transducers are often the most economical option and are made for fibreglass, steel, or alloy hulls. Today's plastic transducers can also offer the same level of performance as their metal counterparts. They are designed to withstand the forces and conditions of the underwater, saltwater world. However, plastic transducers cannot be installed in a wooden hull. As wood swells when it becomes wet, it can generate enough force to crack a plastic transducer housing.

Stainless steel transducers are recommended for use on steel or aluminium hulls and are also compatible with all other hull materials. They are a very stable material but can still be subject to electrolytic corrosion if they come into contact with a dissimilar metal in the presence of saltwater.

Display: depth, speed, temperature, or a combination

When choosing a transducer for your boat, it's important to select one that displays the information you need. Transducers can display depth, speed, temperature, or a combination of these.

Depth

Depth transducers calculate the distance between the device and the seabed, providing essential data for sailing in shallow waters with rocky bottoms, channels with shifting sandbanks, or similar situations. They can also be used for finding fish or determining how much anchor chain to let out.

The transducer emits ultrasound signals, bouncing them off the seabed and measuring the return time of the echo. These signals can be emitted at different frequencies, with lower frequencies (e.g. 50 kHz) providing maximum depth penetration for deep-water fishing, and higher frequencies (e.g. 200 kHz) offering higher resolution and better target separation.

Speed

Speed data is useful for anglers who want to see their chum line and detect fish approaching their chum.

Temperature

Temperature readings can help locate fish, as certain species prefer specific water temperatures.

Combination

Some transducers offer a combination of depth, speed, and temperature data in a single housing. For example, the DST810 Depth/Speed/Temp Sensor is a compact multisensor that can be easily installed and connected directly to the network. Similarly, the B744V TRIDUCER® multisensor provides depth, speed, and temperature data in one housing.

When choosing a transducer, it's important to consider your specific needs and select one that provides the data that is most relevant to your boating or fishing activities.

Power: the strength of the sonar ping

Power is a critical factor in choosing a transducer for your boat, as it determines the strength of the sonar ping. Expressed in watts RMS, the power of the transducer directly impacts the quality of the sonar image. Higher power means a stronger sonar ping, which increases the likelihood of receiving a return echo from the ocean floor or objects in the water. This is especially important in deep water or poor water conditions, where a weaker ping might not be able to penetrate and return a usable image.

A stronger ping also improves the detail of the sonar image. This is important when trying to distinguish between small objects like bait fish and the ocean floor or other underwater structures. The more power the transducer has, the easier it is to separate these echoes and get a clear picture of what's below the surface. This level of detail is critical for anglers, who need to know where fish are located in order to catch them.

The power of the transducer is also important for getting accurate readings in deep water. Lower frequencies penetrate deeper, so a transducer with more power and a lower frequency will be able to provide better readings in deeper water. This is useful for anglers fishing in deep water, as well as for boats that need to know the depth of the water for navigation purposes.

In addition to improving the quality of the sonar image, higher power can also increase the range of the transducer. This is useful for searching large areas for fish or other underwater structures. By increasing the power of the ping, the transducer can scan a wider area and detect objects that are farther away.

When choosing a transducer, it's important to consider the power in relation to your specific needs. If you're fishing in shallow water, for example, you might prioritize a high-frequency transducer that provides detailed images over a powerful transducer that can penetrate deep water. On the other hand, if you're fishing in deep water or an area with poor water conditions, a more powerful transducer will be necessary to get usable readings.

Ultimately, the power of the transducer is just one factor to consider when making a purchase decision. It's also important to think about mounting options, materials, display, frequency, and cone angles. However, by understanding the role that power plays in the performance of a transducer, you can make a more informed choice about which transducer is right for your boat.

Frequency: high (200 kHz) or low (50 kHz)

When it comes to transducers, frequency plays a crucial role in determining the performance of your fishfinder. Raymarine depth transducers offer two frequency options: 200 kHz (high) and 50 kHz (low). The choice between these frequencies depends on the depth of water you intend to explore and the level of detail you require.

High-frequency transducers, operating at 200 kHz, are ideal for shallow water applications, typically under 200 feet or 60 meters. This frequency provides greater detail and accuracy, allowing you to detect very small objects with less noise and fewer undesired echoes. It is perfect for distinguishing fish from structures or the bottom contour. However, the trade-off is a reduction in maximum depth range as the frequency increases.

On the other hand, low-frequency transducers, operating at 50 kHz, are designed for deep-water fishing. Lower frequencies enable sound waves to penetrate deeper, allowing the signal to travel farther before weakening. Additionally, low frequencies provide a wider beam angle, making them suitable for viewing a larger area under the boat. However, this comes at the cost of reduced target definition and separation, and increased susceptibility to noise and interference.

It is worth noting that the choice of frequency also depends on the characteristics of the water body you are navigating. Factors such as mud, soft sand, and plant life at the bottom can absorb and scatter sound waves, affecting the clarity of the bottom image. As a result, it is recommended to use the 50 kHz setting in such conditions, as it provides a wider beam and better penetration.

To get the best of both worlds, consider using a dual-frequency transducer, which offers both 50 kHz and 200 kHz options. This configuration allows you to explore depths of up to 1,500 feet while providing detailed views for shallower applications. Additionally, modern technologies like CHIRP (Compressed High-Intensity Radiated Pulse) further enhance the performance of your fishfinder by continuously sweeping a spectrum of frequencies, resulting in clearer and higher-resolution images.

Frequently asked questions