ACR OLAS Guardian - Engine Kill Switch and MOB Alarm System

Wireless Engine Shutoff

The Guardian monitors the Bluetooth signal from each connected OLAS Tag or Float-On transmitter. If a transmitter is carried overboard or otherwise moves outside the configured range, the system detects the broken wireless connection and activates its engine-shutoff relay.

The relay supports both open-to-stop and close-to-stop engine circuits, allowing the Guardian to be installed in place of or alongside many conventional kill switches. Engine compatibility and wiring configuration should be confirmed with the engine manufacturer before installation.

Immediate Man Overboard Warning

In addition to shutting down the engine, the Guardian activates an internal buzzer, emergency light, and helm-mounted control-switch indicator. This alerts the remaining crew that an OLAS transmitter has left the vessel’s monitored area, helping them begin the man overboard response without relying solely on someone witnessing the incident.

The engine-shutoff function is particularly useful when the operator is boating alone. With multiple transmitters connected, the system can also act as a crew-wide MOB alarm while allowing the engine response to be configured through the ACR OLAS mobile app.

Supports Up to 25 Transmitters

One Guardian can monitor as many as 25 compatible OLAS transmitters, making it suitable for individual boaters, families, work crews, and passenger vessels within its supported range. Each person can wear an OLAS Tag or carry an OLAS Float-On so the system can detect when any connected transmitter moves out of range.

The included OLAS Tag can be worn on the wrist or attached to clothing and personal equipment. Additional transmitters are sold separately.

Mobile App Control

The free ACR OLAS app for iOS and Android is used during setup and provides visibility into the transmitters connected to the Guardian. It can also display a man overboard screen and record the approximate GPS position at which the alarm was activated.

The app and its GPS position are supplementary aids and should be used alongside established MOB procedures, onboard navigation equipment, life jackets, and other marine safety equipment.

Installation and Vessel Coverage

The Guardian hub connects to a 10–32 VDC vessel power supply and the existing engine kill-switch circuit. Its double-throw relay supports both common engine-shutoff arrangements. A 1–3 A fuse must be installed in line with the positive power connection.

The standard system is designed for vessels up to 50 ft. An ACR OLAS Extender can be added where vessel size, layout, or equipment placement requires greater wireless coverage. A full range test should be performed at the dock after installation and before relying on the system underway.

Built for Marine Installation

The Guardian hub uses a water-resistant marine housing and includes separate power, engine-signal, and control-switch connections. The helm control switch provides red and green LED status indication, while the hub contains the internal alarm and emergency light.

All electrical connections should be properly waterproofed with marine-grade connectors, and the hub should be positioned away from equipment that may interfere with its wireless signal.