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SELECTION GUIDE

How to choose an Airmar depth, speed and temperature sensor for a sailboat: frequency, power, mounting style and where to put it on a fin-keel or full-keel hull, with the key specs of the Smart™ and 600 W sensors in the guide.

DocumentAirmar Transducer Selection Guide
FormatPDF · 82 pages · 19.7 MB
LanguageEnglish
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ChoosingMounting StylesSmart Sensors600 W SensorsModels in the GuideProducts
Airmar Transducer Selection Guide

What a Sailboat Needs

  • For sailing and cruising a high-power transducer is not needed: a single-frequency 200 kHz transducer or a 235 kHz Smart™ Sensor is adequate.
  • Accurate depth readings up to 152 m (500'), depending on the depth instrument.
  • A 200 kHz transducer has a limited range of about 200 m (600').
  • Higher frequency: sharper picture, shorter range. Lower frequency (50 kHz): reaches deeper, less detail.
  • Smart™ Sensors at 235 kHz avoid mutual interference with other echosounders on board and output NMEA 0183 or NMEA 2000® directly.

Power Classes in the Guide

  • 600 W: recreational fishing, reads bottom in over 305 m (1,000'), 50 and 200 kHz dual frequency.
  • 1 kW to 2 kW: tournament sport fishing, multi-element, many with Broadband Ceramic Technology.
  • Commercial: 24 kHz to 210 kHz, 1 kW to 4 kW.
  • Single-element 600 W B744V: 45° beam at 50 kHz, 12° at 200 kHz. Multi-element 1 kW SS260: 19° and 6°.
  • Transducer ID® lets a compatible echosounder read the part number, serial number, frequency and power rating from the transducer.

Mounting Styles

Thru-Hull

  • Flush or nearly flush thru-hulls are often installed on sailing vessels because they produce minimal drag.
  • External thru-hulls stand proud of the hull and usually need a fairing to aim the beam vertically.
  • Plastic thru-hull housings must not be used in a wooden boat: the wood swells and may crack the housing.
  • Bronze thru-hull housings must not be used in aluminum or stainless steel boats (galvanic attack on hull and/or housing).
  • Mount where the sensor stays under water at all times, in the smoothest flow, clear of the keel and propeller shaft beam path, away from intakes, discharges, strakes and fittings.

In-Hull and Transom

  • In-hull: shoots through solid fiberglass. Metal, wood and cored fiberglass hulls are not recommended (too much signal loss).
  • In-hull tanks are filled with non-toxic anti-freeze (propylene glycol). No hole, no drag, can be fitted afloat.
  • Transom-mount: not recommended for sailboats because of heeling, and will not work with an inboard engine (turbulence).
  • Transom-mounts give good performance below 30 knots (34 MPH).
Hull Where to mount a thru-hull
Fin-keel sailboat To the side of the center-line and forward of the fin keel 300 mm to 600 mm (1' to 2')
Full-keel sailboat Amidships and away from the keel
Displacement powerboat 1/3 aft LWL and 150 mm to 300 mm (6" to 12") off the center-line, starboard side preferred
Inboard engine Well ahead of the propeller(s) and shaft(s)

Smart™ Sensors (235 kHz)

Model Measures Frequency Beam (-3 dB) Hull deadrise Min depth Max range Weight
DST800 Depth, speed, temperature (TRIDUCER®) 235 kHz 10° × 44° Up to 22° 0.5 m (1.6') Up to 70 m (30') NMEA 0183 (as printed) / up to 100 m (330') NMEA 2000 0.9 kg plastic / 1.6 kg bronze / 1.9 kg stainless
D800 / DT800 Depth (D800), depth + temperature (DT800); 0°, 12° or 20° tilted element 235 kHz 12° – 0.5 m (1.6') Up to 100 m (330') non-broadband / up to 180 m (590') broadband 0.9 kg plastic / 1.5 kg bronze / 1.6 kg stainless
B122 Depth + temperature, retractable long-stem, bronze only, High-Performance Fairing included 235 kHz broadband 12° Up to 28° with fairing 0.5 m (1.6') Up to 180 m (590') 3.9 kg (8.7 lb)
ST800 / ST850 Speed + temperature (no depth) – – Up to 22° – Speed 2 to 45 knots 0.7 kg plastic / 1.3 kg bronze / 1.6 kg stainless

Common Specs

  • Supply 10 VDC to 25 VDC (NMEA 0183, <40 mA) or 9 VDC to 16 VDC (NMEA 2000, <200 mA).
  • Standard cable 10 m (33') NMEA 0183 or 6 m (20') devicenet NMEA 2000.
  • Temperature accuracy ±0.5°C (±1.8°F), range -10°C to 40°C (14°F to 104°F).
  • Data update 1 per second; pressure rating 3 m (10').
  • Speed pulse rate 20,000 p/nm (5.6 Hz per knot).
  • NMEA 2000 LEN: 4 (DST800, DT800, B122), 2 (ST800 / ST850).

Fitting Notes

  • DST800: depth, speed and temperature through one 51 mm (2") hole; wide fore-aft beam finds bottom on heeling sailboats.
  • DST800 and DT800 use the P617V, B617V or SS617V housings; DT800 also fits B17 and SS577 housings.
  • ST800 retrofits into P120 / B120 housings; ST850 into P17 / B17 housings.
  • ST850 low-profile housings protrude only 5 mm (3/16"); flush P217 / B119 / P314 / B21 housings are listed as the choice for racing sailboats.
  • Self-closing valve limits water flow when the insert is pulled.
  • CS4500 ultrasonic speed sensor: no paddlewheel, 0.1 to 40 knots, fits most Airmar 51 mm (2") housings.

The DST800 page lists ±0.2°C in its features and ±0.5°C in its specifications; both as printed.

600 W 50/200 kHz Sensors

Model Type Hull deadrise Boat size Weight
B45 Thru-hull bronze stem Up to 26° with fairing Planing powerboats and cruising sailboats up to 9 m (30') 2.5 kg (5.5 lb)
B60 / SS60 Thru-hull, Tilted Element™ (12° or 20°) Up to 24° Up to 8 m (25') 1.4 kg (3 lb)
B744V / B744VL Thru-hull TRIDUCER® (depth, speed, temperature) Up to 24° with fairing Up to 9 m (30'); VL for thicker / high-deadrise hulls 2.5 kg (5.5 lb)
P79 In-hull, adjustable, depth only 0° to 22° Up to 8 m (25'); listed for racing sailboats 2.3 kg (5 lb)
600 W, 50/200 kHz 50 kHz 200 kHz
Beamwidth (-3 dB) 45° 12°
Max depth: B45, B60, B744V 235 m to 353 m (800' to 1,200') 118 m to 206 m (400' to 700')
Max depth: P79 (in-hull) 206 m to 294 m (700' to 1,000') 118 m to 180 m (400' to 600')
Beam diameter at 30 m (100') 25 m (83') 6 m (21')

B60 tilt choice: 20° tilt for 16° to 24° deadrise, 12° tilt for 8° to 15°. The arrow on the cap points toward the keel. B744V speed range 1 to 45 knots.

Models in the Guide

Group Models
Transom-mount TM270W (1 kW wide-beam), TM260 (1 kW), TM258 (1 kW entry-level), P66 (600 W TRIDUCER®), P48W (wide-beam, 200 kHz), P39 (TRIDUCER® Smart™)
Thru-hull, tilted element B60 / SS60 (600 W), B164 / SS164 (1 kW), SS264W and SS264N pairs (1 kW), D800 / DT800 (Smart™)
Thru-hull B45 (600 W), B744V / B744VL (600 W TRIDUCER®), B258 (1 kW), B260 / SS260 (1 kW), SS270W (1 kW wide-beam), R99 (2 kW external-mount), B122 (Smart™)
In-hull P79 (600 W, adjustable), M260 (1 kW)
Speed / temperature DST800 (depth, speed, temperature), ST800 / ST850 (speed and temperature), CS4500 (ultrasonic speed), B17-HP, T42, T25 / T80 (temperature)
Weather and navigation PB200 and PB150 WeatherStation® instruments, LB150, H2183 heading sensor, GH2183 heading sensor with GPS, G2183 GPS sensor, U200 NMEA 2000® to USB gateway
Other SB264 1 kW switchbox, CA500 thru-hull underwater camera

Each model has a feature page and a technical page with dimensions and data output (NMEA 0183 sentences and NMEA 2000® PGNs) in the PDF.

Need a part that isn't listed? Ask us to source it and quote the part number from the PDF.

Products in this Selection Guide