Raymarine CPT-S 20° Thru-Hull CHIRP Transducer (Bronze) – 900ft, 25° Cone

The E70341 CPT-S 20° is a bronze thru-hull CHIRP transducer, designed to ensure the sonar beam is optimally oriented on hulls with a deadrise of approximately 15° to 25°. Thanks to its built-in 20-degree tilt, installing this transducer means its 25° conical beam will point straight down despite the hull’s angle – critical for accurate, vertical sonar readings. The CPT-S 20° uses a high-frequency CHIRP fishfinder sonar operating around the ~160–200 kHz range (typically centered ~170 kHz). It is a single-element transducer focused on delivering clear conical fish echoes and depth measurements, without any structure-scanning elements.

The transducer features a low-profile bronze housing that sits nearly flush with the hull when installed. Bronze is the preferred material for thru-hull transducers due to its strength and resistance to corrosion in fiberglass and metal hulls. The CPT-S 20° is suitable for fiberglass or metal hulls (steel, aluminum); it’s generally not recommended for wooden hulls (since wood can swell and shrink, requiring periodic tightening of bronze fittings). The required hole diameter is standard for this class of transducer (around 2″ or 51 mm), and the kit includes the fairing (built-in angled face) and a locking nut for securing from the inside. When properly installed with marine sealant, the transducer is watertight and secure – ready for long-term service. Its depth capability reaches 900 feet (274 m), covering all coastal and most offshore fishing or cruising needs. The 25° beamwidth provides a good balance of coverage and resolution, clearly showing fish targets and bottom contours directly under the vessel. An integrated temperature sensor offers water temperature data to the system – useful for tracking thermoclines and environmental conditions.

Compatibility: The CPT-S 20° bronze transducer is part of Raymarine’s CPT-S family and shares the same electrical specs as the plastic transom models. It connects directly to Raymarine Element S series chartplotter/fishfinders and to Axiom DV (DownVision) models without need for adapters. For the Axiom Pro S / Axiom 2 Pro S series, which have built-in High CHIRP sonar, the A80490 adapter is required – after which this transducer becomes the recommended fishfinder transducer for those units. To interface with Element HV displays (which normally use HyperVision transducers), the A80559 adapter is available; with this combination, the CPT-S will provide only the High CHIRP sonar function (Element HV will operate in standard sonar mode). The transducer can also be used with older systems via appropriate cabling – e.g. Dragonfly 4/5/7 (using adapter A80518) – if one wants to add a straightforward fishfinder sonar channel. CP100 modules also support CPT-S as a 200 kHz sonar input (in addition to DownVision with a different transducer), although typically CP100s are paired with CPT-100DVS. In short, the CPT-S bronze transducers offer a lot of flexibility when upgrading or switching equipment, since they can work with a wide array of Raymarine products.

Recommended Use: This 20-degree bronze transducer is ideal for sailing yachts and larger powerboats that have V-hulls with moderate to steep deadrise. Instead of using a transom transducer (which on a sailboat may be undesirable or impractical), many owners opt for a thru-hull bronze transducer for reliable and accurate readings. The CPT-S provides depth data for navigation (it can feed depth information to instrument displays via network modules) as well as fishfinding capability – especially useful on cruising sailboats that occasionally fish, or on sportfishing boats that want a simple yet high-quality sonar setup. Because the CPT-S lacks DownVision or SideVision, it’s aimed at users looking for a dependable traditional sonar (fishfinder) without needing advanced 3D/side-scan features. For example, if you have a 30-foot motor yacht with an Axiom display used for family cruising and casual fishing – this transducer would give you steady depth readings at all speeds and a solid view of fish beneath you. The bronze build ensures longevity – many mariners know that a well-installed bronze transducer can perform for decades. With a 2-year warranty and adherence to marine standards, the Raymarine CPT-S 20° is a trusted choice for anyone looking to outfit their boat with a modern CHIRP sonar via a thru-hull installation.