SART vs AIS SART
SART vs AIS SART — What They Are and Do You Actually Need One?
I will be honest — I didn’t know much about SARTs I had very little hands-on experience with them until I researched this article properly. I have seen them on vessels, usually mounted near the bridge wing doors or stowed with the liferaft kit, but they are one of those pieces of equipment that most people on board have never actually used.
Which is exactly why this matters. If you have a SART on board and do not understand what it does, it will not help you when you need it.
What Is a SART?
SART stands for Search and Rescue Transponder. It is a small bright orange handheld device designed to guide rescuers to your exact position once a search and rescue operation is already underway.
Here is the key thing most people miss: a SART is not the same as an EPIRB. An EPIRB calls for help — it alerts a rescue coordination centre globally via satellite. A SART guides rescuers to you once they are already in your area looking.
Think of it this way. The EPIRB is the alarm. The SART is the flashing light that gets the rescue helicopter to the right spot.
How Does a Radar SART Work?
The tech – A Radar SART responds to X-band radar — the type fitted on most commercial vessels and search and rescue craft. When a ship or aircraft sweeps its radar across an activated SART, it detects the pulse and immediately transmits back a series of 12 pulses. These appear on the radar display as a line of 12 dots pointing directly to your position.
As the rescue vessel closes within about one nautical mile, those dots turn into concentric arcs — unmistakable on any radar screen.
Standby life: 96 hours. Active transmission once triggered: minimum 8 hours.
What Is an AIS SART and How Is It Different?
An AIS SART has its own built-in GPS and transmits your exact position as an AIS message directly to any vessel or shore station with AIS equipment. It appears as a distress target on their chartplotter with an alarm — precise and immediate.
The trade-off: it only works with vessels that have AIS. A radar SART works with any vessel that has standard marine radar.
In UK coastal waters where most commercial traffic carries AIS, the AIS SART is increasingly effective. In remote offshore areas with less traffic, radar coverage may be broader.
Quick Comparison
Radar SART — detected by any X-band radar. Shows as 12 dots on radar screen. No built-in GPS. Range 5 to 10 nautical miles from surface, 30 or more miles from aircraft.
AIS SART — detected by any vessel with AIS. Shows as exact GPS position with distress alarm on chartplotter. More precise. Requires rescuers to have AIS.
Do You Actually Need One on a Recreational Boat?
For commercial vessels of 300 gross tons and above — yes, SOLAS requires it. For recreational vessels under 13.7 metres in UK waters — no legal requirement.
My honest view: for coastal day sailing with an EPIRB and PLB, you are well covered. For serious offshore passages — longer crossings, overnight sailing, remote waters — a SART adds meaningful precision during the search phase of any rescue. When rescuers are looking for you in rough conditions at night, that precision matters enormously.
Where Should You Store It?
On deck and immediately accessible — not below. Alongside the liferaft and EPIRB. In a real emergency you may have very little time. Hold it as high as possible when activated — the higher the antenna, the greater the range.
Our Recommended Products
McMurdo SmartFind S5A AIS SART
My favourite and reputible. The rugged McMurdo SmartFind S5A AIS SART is buoyant and waterproof to a depth of 10m. When activated, the SmartFind S5A transmits an alert message.
SART Pathfinder Transponder VAI8
The budget friendly: The Pathfinder SART Transponder is designed with exceptional water tightness, ensuring reliable performance at depths of up to 10 meters. With a guarantee of maintaining water tightness for at least 5 minutes, this device offers peace of mind during critical search and rescue operations, even in harsh aquatic environments.
FAQs
Can a SART replace an EPIRB?
No. They do completely different jobs. EPIRB calls for help globally. SART guides rescuers to you locally. You need both.
Does a SART need registering?
Radar SARTs do not require registration in the same way as EPIRBs. AIS SARTs have unique MMSI numbers. Check the manufacturer documentation for your specific device.
How do I test one?
Most have a built-in self-test function. Follow the manufacturer instructions carefully — a full activation in harbour is a false distress alert and is illegal.
Always verify current carriage requirements at gov.uk/mca and imo.org. Regulations are reviewed periodically.
The information in this article is for general guidance only and does not constitute professional safety advice. Always consult current MCA, SOLAS, and HSE official documentation and a qualified marine safety professional before making any safety-critical decisions. Product specifications and regulatory requirements change — always verify against current official sources before purchase. Where affiliate links appear on this site, they are clearly disclosed and never influence our recommendations. marinesafetyguide.com participates in affiliate programmes including Amazon Associates and the Awin network and may earn a small commission on purchases made through links on this site, at no extra cost to you.
