Raymarine ST900/P120 Retractable Speed/Temp Transducer
- Brand:
- Raymarine
- Part no:
- E70673
Image: harbor-supply.com
Where to buy
Specifications
- Mount
- Thru-hull
- Sensor
- Paddlewheel
- Material
- Plastic
- Max speed
- 45 kt
- Retractable
- Yes
The Raymarine ST900/P120 is a retractable thru-hull transducer that reports boat speed and water temperature. Its Gen2 paddlewheel starts reading speed from 0.3 knots and covers up to 45 knots, with a temperature range of -10° to 40°C. Output is analog, for instruments such as the i40, i50 and iTC-5 and older systems. The cable is 13.7 m (45 ft) long. The core can also be fitted into existing Airmar P120 and B120 housings.
Our take
The Gen2 paddlewheel starts reporting speed from 0.3 knots, so slow manoeuvring speeds still register, and its range runs to 45 knots. The retractable thru-hull body means the paddlewheel can be pulled for maintenance.
From our buying guide
Speed sensors use a paddlewheel, or ultrasonic transducers with no moving parts. Both foul: Airmar says growth can impede or freeze a paddlewheel within weeks, and also reduces an ultrasonic sensor's performance.
Check before you buy:
- It suits your hull, since Airmar does not recommend its UDST800 for hulls designed to pull air under them.
- The housing suits your hull too. Airmar and Raymarine rule out plastic on a wood hull and bronze on a metal one.
- You'll calibrate it once fitted, since Raymarine says the reading depends on where it sits, the hull shape and the water flow.