ACR SM-3 Self-Igniting Lifebuoy Marker Light — Auto Water-Activated, 360°, USCG/MED/SOLAS | ACR 3947
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The ACR SM-3 Self-Igniting Lifebuoy Marker Light 3947 is a SOLAS-approved crew-overboard marker light designed for lifebuoys, commercial vessels, workboats, yachts, passenger vessels, and offshore safety stations. It uses a high-intensity LED strobe with 360° visibility for approximately 2 miles, automatically activates when deployed in the water, and floats upright to help mark a person-overboard location during recovery.
Key Features
- ACR part number 3947 — SM-3 SOLAS lifebuoy marker light
- USCG, MED, and SOLAS approved
- Self-igniting design with automatic gravity-switch activation
- High-intensity LED strobe with minimum 3 candela light intensity
- 360° visibility for approximately 2 miles
- Flash rate: 50–70 flashes per minute
- Floats upright in all conditions
- Operating life: 40+ hours at 30°C / 86°F
- Cold-temperature operating life: 24+ hours at -1°C / 30°F
- Uses 2 AA Energizer L91 lithium batteries, not included
- User-replaceable batteries
- UV-resistant polycarbonate housing
- International safety orange body
- Size: 9.9" length x 2.2" diameter / 253 mm x 56 mm
- Weight: 0.66 lb / 300 g light only, 0.90 lb / 406 g with batteries and bracket
- Includes UV-resistant mounting bracket
- Bracket uses the same mounting hole pattern as the previous SM-2 for easier retrofit
Intended Use
The SM-3 is intended for lifebuoy and crew-overboard marking applications on commercial marine vessels, passenger vessels, cargo ships, workboats, tugs, supply vessels, fishing vessels, yachts, and other boats requiring an approved self-igniting lifebuoy light. It is designed to be mounted with a lifebuoy station and deployed overboard in an emergency.
Fitment Notice
This is a lifebuoy marker light, not a personal PFD light. Confirm your vessel’s required approval standard, carriage requirements, mounting location, and lifebuoy setup before installation. For vessels replacing an older ACR SM-2, the SM-3 bracket maintains the same mounting hole pattern for easier retrofit.
When This Product Needs Replacement
Replace the light if the housing is cracked, the bracket is damaged, the strobe fails testing, the unit no longer activates reliably when inverted/deployed, the battery compartment shows corrosion, or the product no longer meets the required vessel safety standard. Batteries should be replaced after emergency use, during scheduled safety checks, or before expiry.
Installation Notes
Install the included bracket at the lifebuoy station where the light can deploy freely with the buoy. The SM-3 activates by gravity switch when thrown overboard or turned upright with the LED facing skyward. Install fresh AA L91 lithium batteries, verify the battery compartment is sealed, and test operation as part of the vessel’s safety-equipment inspection routine.
Alternate/Superseded Part Numbers
Related ACR references include:
- 3947 — SM-3 Self-Igniting Lifebuoy Marker Light
- SM-3 — model reference
- SM-2 — previous ACR lifebuoy marker light family referenced for retrofit mounting
Parts Desk Insight
The SM-3 is built for lifebuoy stations, not wearable PFD use. The important checks are approval standard, bracket location, and whether the light will deploy cleanly with the buoy. The shared SM-2 mounting hole pattern is helpful when updating older vessel safety stations.
Shipping: Ships within 3 days for fast Canada wide shipping. ⚓
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.