GARMIN P79 INDOOR TRANSDUCER
600W NMEA 2000 Indoor Plastic Transducer
Transducer suitable only for numerical indication of the seabed, NOT for the Fishfinder option.
Connection via NMEA 2000 network, 5PIN connector.
Frequencies: 50-200khz
Dual frequency transducer for internal mounting in oil bath, 600w power compatible with echomap 50s, 70s, gpsmap 527xs, 721xs, 820xs, 1020xs series instruments.
Product Number: 010-10327-20
Factors to consider when choosing a transducer
To determine the transducer best suited to your needs, consider the following factors:
Material
The first point to determine is the material the transducer is made of.
The plastic transducer is recommended for fiberglass or metal hulls.
The stainless steel transducer is recommended for aluminum or steel hulls.
The bronze transducer is recommended for fiberglass or wooden hulls.
Expanding wood can damage plastic transducers and cause a leak. Installing a stainless steel transducer in a metal hull requires the use of a fairing, available from your dealer.
DO NOT install a metal transducer on a positive ground vessel.
Mounting type
The type of assembly is also very important.
Thru-hull transducers with fairing blocks offer the best performance, especially at high speeds.
Thru-hull transducers are ideal for towing vessels where good performance is required and there are no protrusions from the hull.
Internal transducers are fixed directly inside the hull but performance is slightly reduced.
Transducer output power
Output power refers to the intensity at which the transducer sends signals expressed in watts RMS.
Higher power increases the chances of obtaining returns in deep water or poor visibility. It also allows you to see more detail, such as small fish and structure.
Typically, the higher the power, the greater the depth you can reach, as well as achieving maximum target separation by eliminating surface clutter.
Frequency
The accuracy with which the fishfinder locates the bottom and other objects is also determined by the frequency selected based on depth. Raymarine depth transducers have two frequencies: LOW or HIGH .
HIGH
The high frequency is used for shallow water and is used to obtain more accurate readings at high speeds. When using this frequency, the transducer scans a smaller area but displays greater detail. Typically, fewer unwanted echoes and less clutter are displayed, resulting in greater target definition.
LOW
This frequency is used in deep waters. Water absorbs ultrasonic pulses at a slower rate, and larger areas can be covered before the signal becomes too weak. This results in a wider cone angle, allowing for a larger portion of the seabed to be scanned. However, this also means less definition and target separation, and more noise. While low frequencies allow for deeper exploration of the water column, they can also result in a less clear image of the seabed.
In general, you should use the high frequency for a detailed image in shallow water and then switch to the low frequency for greater depths. The ideal solution is to display both frequencies on a split screen.
Angles of the cone
The transducer focuses the transmitted waves into a beam. In theory, the pulses are radiated in a cone that widens as the depth increases. In reality, the beam shape varies depending on the transducer, and the pulses are typically also radiated outward, thus producing sidelobes. The following figures show a representation of the actual path taken by the pulses.
Low frequencies have a wider beam angle than high frequencies
However, for our purposes, we'll consider the image of a cone. The signal is strongest along the centerline of the cone and gradually decreases as we move away from the center. Wider angles show a larger portion of the seabed, but at the expense of resolution because they disperse the transmitter's power. A smaller cone can concentrate the transmission power more in a smaller area. Cone angles are wider at low frequencies and narrower at high frequencies.
In summary, a wider beam can detect not only fish directly under the boat but also surrounding fish, but with less target separation. A narrower beam focuses the transmitted energy to more precisely locate small details, such as fish or bottom structure, but scans a smaller portion of water.
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