Fast Water Aids to Navigation Help Protect Property and River Users

Sealite Case Studies

Fast Water Aids to Navigation Help Protect Property and River Users

Fast Water Aids to Navigation Help Protect Property and River Users

By:Sealite | September 10, 2020
Application: Rivers with Fast Currents
Fast Water Buoy in Regulatory Slow No Wake Style (SL-B1200)
Solar LED Marine Lantern with 1-2NM Range (SL-15)
Location: Merrimack River, Massachusetts, USA
Date: 2019, 2020


The 117 mile (188km) Merrimack River begins in the USA’s state of New Hampshire. It empties into the Gulf of Maine, via the state of Massachusetts. Currents and tides run fast in its lower section. Shifting sandbars quickly drop off to deeper water. Tides, currents and rip currents in the picturesque New England river present unsuspecting dangers to boats and river users.

The last 8 miles of the Merrimack River are navigable. It is a relatively shallow section of the river with a current that typically exceeds 5 kts. There is little commercial vessel traffic along the lower part of the river now, but it is seasonally used by several thousand recreational boats, kayaks, Stand Up Paddle boards (SUPs), school crew teams, as well as a few fishing fleets.

The river’s main channel is marked with aids to navigation (AtoNs) by the U.S. Coast Guard. Municipal marine patrol agencies monitor the local boating traffic and work to minimize damage from the wakes of speeding vessels. Excessive speed creates large wakes that swamp smaller craft, damage docks and vessels, erode shorelines, and disturb nesting waterfowl.


Jack Bailey has served as a local harbormaster for decades. It’s his job to ensure everyone who uses the Merrimack River in his jurisdiction is safe. He had previously used Slow No Wake buoys to remind passing boaters to keep headway speed to a minimum. But the river’s swift current pushed them over, submerged them, or dragged them off-station. The marine lanterns he had used for nighttime buoy illumination failed from water ingress. Harbormaster Bailey sought a better solution to keep his floating AtoNs visible to all users in the swift river current.


Harbormaster Bailey knew Sealite’s SL-B1200 Fast Water Buoy would be an optimal marking solution for the swift current of the Merrimack River. The innovative design of the SL-B1200 features a combination of a traditional float-collar buoy and boat hull. The integrated bow and keel help keep the buoy in the current. A relatively flat bottom allows water to flow underneath it, instead of pushing it over or submerging it. Sealite’s SL-B1200 remains stable as it rides on top of the water, helping to increase visibility for the Slow No Wake message to passing boaters.

The SL-B1200 is available in regulatory and navigation styles in IALA compliant colors. All of Sealite’s buoys are rotationally molded to eliminate seams. Rotational molding also ensures uniform thickness for strength and durability. The material used in the molding process is UV stabilized polyethylene to help the buoys resist fading in strong UV environments. Closed-cell polyurethane foam filling helps inhibit water ingress in case of puncture from a boat collision or ice –
both of which are frequent occurrences on the Merrimack River.

Sealite’s SL-15 1-2NM Solar LED Marine Lanterns were installed on the SL-B1200 Fast Water Buoys. The lanterns add visibility for the buoys at night and in foul weather. The SL-15s are designed to be maintenance-free, utilizing a single, white LED with a life expectancy of 100,000+ hours. An autonomy of 50+ days is achieved with the use of an easily replaced NiMH 2.4Ah battery. The SL-15s are completely sealed and waterproof to IP68 standards, feature 16 user-adjustable flash characteristics, and 32 intensity settings, and are available in green, red, white and yellow.


After two years of use, Harbormaster Bailey has complete trust in the Sealite SL-B1200 Buoys with SL-15 Solar Marine Lanterns. The Slow No Wake regulatory signage on the buoy is highly visible to passing boaters and the marine lanterns have provided years of reliable service. The Merrimack River is safer for users, damage to docks and boat has been reduced, shoreline erosion has slowed and nesting waterfowl have gone undisturbed.


“The Sealite buoys are the best option to mark my section of the river. They look and perform so much better than the other buoys. And the lanterns have worked flawlessly for 5 years before requiring a battery change! It’s a great solution for rivers with fast currents like the Merrimack.”

Jack Bailey, Harbormaster, City of Amesbury

What Our Client's Say

On behalf of Karachi Port I am pleased to acknowledge your good service and provision of the new SL-75 solar marine lanterns installed by your firm in the harbour channel at Karachi Port. The new lanterns are very feasible and useful and equipped with the latest navigational technology.

-Captain Muhammad Altaf

[Re: Sealite SL-LED Lightsource at LaCorbiere Lighthouse], We were impressed with Sealite’s solution which provided a modern, reliable and efficient light source whilst remaining sympathetic to the lighthouse’s heritage and significance as a local landmark, but most importantly to improve upon reliability and to continue its vital role in aiding the safety of navigation in Jersey’s waters, as it has done for nearly 130 years.

-Aaron Gavey

[Re: Sealite Wins Duke’s Choice Award for Java Technology & the Environment – Sealite GSM monitoring & control system]. The team at Motorola were extremely impressed with Sealite’s innovative integration of the G24-Java wireless module in their GSM Monitoring & Alarm System.

-Golan Haver

As one of your new distributors (Belize and Honduras, Waller Marine Belize LTD), I would like to express my congratulations to you and your people in providing reliable, dependable and inexpensive products. Formerly we were distributors for a Canadian made product but these were found to be too expensive for the market and also offered only difficult and complicated programming. Our first order of lights from you (SL15’s) took only four days to arrive from Aussie Land, when I opened the box they were still flashing. I tested a SL60 (white) for four days (steady on) before it required a recharge…remarkable. I will be placing another order shortly. Keep up the good work.

-Capt Andy Suddes

[Re: Installation of WindTalker for kite-surfing club], The WindTalker™ is a big success here in Cyprus, thanks to your after sales support the unit is now functioning perfectly.

-Christophe Meletiou

We choose to sell Sealite … this is a long story, well we treat Sealite as our own and the relationship we have developed with Jeff and Chris and their attitude and commitment towards growing Sealite to this stage is remarkable. We feel at home when talking to them and the staff of Sealite and this in turn gives us more security and strength in selling products in India.

-Aliasgar E Patrawala

[Re: Sealite Solar-Powered LED Area Lighting system], We chose the Sealite system for the Jacobs Well Queuing Pontoon due to our previous experience with Sealite’s product, its durability and construction.

-Peter Taylor

I just wanted to say thank you for the light and bracket Sealite supplied to Birkenhead Marina. As the other lights (old ones) need new batteries I will be replacing them with new lights from Sealite and the same brackets that you supplied with the light we received last week … Your product is excellent and the system of setting the light is good also. Thanks again for all your trouble.

-Philip McGowen