Upgrade your vessel's navigation with the Raymarine ST900 speed and temperature sensor, a thru-hull powerhouse designed for precision in demanding marine environments. This low-profile bronze thru-hull transducer delivers unmatched responsiveness, capturing boat speeds from a whisper-quiet 0.3 knots up to a blistering 45 knots. Paired with fast-response temperature readings, it equips sailors and powerboaters with critical data for optimal performance, whether you're racing offshore or tracking fish-holding thermoclines.

Exceptional Gen2 Paddlewheel Technology

At the heart of the ST900 lies Raymarine's innovative Gen2 paddlewheel, engineered for superior startup sensitivity and linear accuracy across the full speed spectrum. Unlike traditional sensors that lag at low speeds or falter at high velocities, this next-gen design ensures smooth, reliable data from idle to full throttle. The result? Confident decision-making on speed-over-ground adjustments, fuel efficiency calculations, and tactical racing strategies.

Sleek Low-Profile Design Minimizes Drag

Crafted with a bronze housing for corrosion resistance in saltwater, the ST900 extends just 5 mm (3/16") beyond the hull—nearly flush for reduced hydrodynamic drag. Its retractable insert features a built-in valve that seals the hull during maintenance, keeping your bilge dry and downtime minimal. Perfect for sleek racing hulls or performance cruisers where every bit of speed counts.

Versatile Analog Output and Easy Retrofits

With analog output, integration into legacy Raymarine displays and multifunction systems is seamless. It retrofits effortlessly into popular Airmar P120 and B120 housings, extending the life of your existing setup without hull modifications. The 13.7m cable provides ample reach for clean routing to your helm station.

Key Benefits for Boaters

• Industry-leading low-speed accuracy for anchoring, docking, and light-air sailing
• Fast temperature response to detect water column changes for fishing or engine monitoring
• Bronze construction withstands harsh marine conditions year after year
• Valve-equipped housing simplifies paddlewheel cleaning and servicing
• Broad speed range suits dinghies to large yachts

Technical Specifications

Installation Tips for Peak Performance

Position the thru-hull 1/4 to 1/3 of the waterline length forward of the rudder post, in undisturbed water flow. Fair the housing to match hull contours for zero turbulence. Always bed with marine sealant, torque to spec, and calibrate post-install via your Raymarine display for true boat speed.

Frequently Asked Questions

Equip your boat with the ST900 and experience the difference in data-driven boating—reliable, responsive, and ready for adventure.