Overview
Speed and Temperature The ST850 is a low-profile, retractable, thru-hull sensor that computes accurate speed and temperature data and sends it to any NMEA 0183 display or NMEA 2000 ® network.
These low-profile units are nearly flush, minimizing drag with only 5 mm (3/16″) extending outside of the hull.
The housing features a water valve which minimizes water ingress into the boat when the retractable insert is being replaced with the blanking plug. Airmar’s Smart ™ Sensors have embedded microelectronics. The signals from the speed and temperature sensors are processed right inside the housing itself. All that is needed to receive data is a single cable into a compatible network or display. Available as an analog sensor or a digital Smart Sensor that can output in NMEA 0183 or NMEA 2000 protocol.
Technical specifications
| Cable-Length | 6 m (20′) NMEA 2000® Cable |
|---|---|
| Common Use | Cruising/Racing Sailboats, Leisure/Yachting, Fishing |
| Data Rate | 1X per second |
| Functions | Speed, Temperature |
| Hole Size | 51 mm (2″) |
| Housing | Available in a plastic (P17) or bronze (B17) housing with water valve |
| Hull Material | Plastic: Fiberglass or metal, Bronze: Fiberglass or wood |
| Mounting Style | Low Profile Thru-Hull |
| Power Rating | N/A |
| Product Family | Marine |
| Protocol Output | NMEA 2000® |
| Pulses | 17,000 p/nm* (4.8 Hz per knot)—*p/nm = pulses per nautical mile |
| Retractable housing | Yes |
| Retrofits | Retrofits into B617V, P617V, SS617V, P217, P314 or ST650 housing |
| Speed Range | 2 to 45 knots (2 to 52 MPH) |
| Speed Type | Paddlewheel |
| Temperature Accuracy | ±0.5°C (±1.8°F) |
| Tilted Element | No |
| Usable Shaft Length | 57 mm (2.25″) |
| Voltage | 9 to 16 VDC |
| Water Temperature | -10° To 40°C (14° to 104°F) |
| Weight | Plastic: 0.7 kg (1.4 lb.), Bronze: 1.3 kg (2.8 lb.) |
FAQs
What is the pressure rating for the ST850 installation?
The ST850 has a pressure rating of 3 m (10’).
Is the ST850 retractable for maintenance or cleaning?
Yes, the ST850 features a retractable housing that allows removal for cleaning or inspection without significant water ingress.
What type of hull deadrise is supported for installation?
The ST850 supports installation on hulls with deadrise up to 22°, accommodating a variety of boat shapes.
What output protocol formats does the ST850 support?
The ST850 Smart Sensor supports both NMEA 2000 and analog output protocol formats.
How much does the ST850 Smart Sensor extend outside the hull?
The ST850 housing is nearly flush, extending only 5 mm (3/16″) outside of the hull to minimize drag.
What type of speed measurement technology is used in the ST850?
The ST850 uses a paddlewheel mechanism for speed measurement.
How often does the ST850 update speed and temperature data?
The ST850 updates speed and temperature data once per second.
What is the rated operating temperature range for the water sensor?
The temperature sensor operates from -10°C to 40°C (14°F to 104°F).
Who do I contact for help with installation, servicing or advice?
Contact the SailRACE team — as certified marine experts we’re happy to help with product selection, installation and after-sales servicing, before and after your purchase.
