Overview

The Simrad 000-13770-001 is the XSONIC TM275LH-W transom-mount CHIRP transducer with wide-angle Low and High coverage for fishing and bottom tracking. It runs Low CHIRP from 42 to 65 kHz and High CHIRP from 150 to 250 kHz, with a High channel that holds a constant 25° beam for broad returns in the upper water column.

This is a dual-channel transducer with dual black 9-pin connectors and a 10 m (33 ft) cable, plus an integrated water-temperature sensor. The body measures about 108 x 191 x 74 mm (4.3 x 7.5 x 2.9 in) without the bracket and weighs 4 kg (8.9 lb), so plan for a solid transom mount and tidy cable routing.

Key features

• Dual-channel CHIRP in one transducer: Low 42 to 65 kHz and High 150 to 250 kHz.
• High CHIRP keeps a constant 25° beam width for wide coverage when you are watching bait and targets above the bottom.
• Low CHIRP beamwidth shifts from 25° down to 16° across the band to keep bottom returns readable as depth increases.
• Low CHIRP depth capability up to 1200 m (4000 ft), depending on installation, sea state, and bottom conditions.
• Eight internal broadband ceramic elements.
• Urethane housing with a stainless steel mounting bracket for transom mounting.
• Dual black 9-pin connectors with a 10 m (33 ft) cable for separate Low and High channels.
• Built-in water-temperature sensor for surface temperature readings.
• Bracket compatibility with TM258 and TM260 mounting patterns for straightforward upgrades.

Compatibility and fit

This transducer uses two 9-pin connectors for separate Low and High channels, so the sonar source needs dual-channel CHIRP support and the correct ports or adapter arrangement. It is often paired with a BSM-3 sounder module when a dedicated sonar module is part of the system.

It is commonly installed on boats about 8 m (25 ft) and up where the transom can keep the transducer in clean water flow at speed. If your transom has steps, strakes, or a bracket that throws aerated water, placement matters more than raw specs.

Installation and setup

Mount the bracket so the transducer face stays in solid water when you are on plane, away from prop wash and hull features that feed bubbles. A small height change can make a big difference, so plan for a short sea trial and adjustment after the first runs.

Route the cable with gentle bends and a drip loop, and keep it separated from high-current wiring when possible. On the display or sonar module, set up separate Low and High channels so you can use Low for deep bottom work and High for wide coverage in the upper water column.

Use cases on board

This is a strong match for offshore fishing, deep structure work, and faster boats that still need wide coverage under the transom. It also fits boats that are upgrading from older transom-mount CHIRP hardware and want to keep a familiar mounting footprint.

Maintenance and care

Rinse the housing and bracket after saltwater use, and check the bracket hardware for tightness after the first few trips and any long run in chop. Keep the transducer face clean and avoid harsh solvents so the urethane surface stays in good shape.