ExploMar electric outboards’ excellent summer: batteries, races, chargers, whale watching

High power electric outboard motor manufacturer ExploMar is riding high after a stretch of race victories, technology leaps and new partnerships in the electric boating world.

• At the Venice Boat Show in June they debuted their  Super Island Battery Platform that enables a range of 200km (MI NM)
• At July’s Monaco Energy Boat Challenge they triumphed over some stiff competition to win the 16 Nautical Mile Race
• In early August they announced that they would be the latest high powered electric outboard able to plug into the expanding Aqua superPower Network of high speed DC chargers and
• September saw the Portugal launch of a Tideman Boats all-electric whale-watcher with ExploMar motors

Super Island (SI) battery platform at Venice

The ExploMar Super Island (SI) battery platform unveiled at the Venice Boat Show has been developed by ExploMar specifically the needs of their electric outboards that have power ranging from 70 kW to 229 kW (108 hp to 300 hp).

Read: Plugboats Guide to Electric Boat Batteries

Using NMC chemistry (Nickel Manganese Cobalt), the SI’s next generation battery cells have a very high energy density of 250 Watt hours per kilogram. The cells are just the beginning of making a battery for an electric boat, though.

To produce the final pack requires connecting those cells together to create battery modules, with the modules then assembled and enclosed in an 1P67 waterproof casing to create the battery pack. All of that extra weight lowers the overall energy density, but for complete packs the SI units still have an exceptionally high density of 165 Wh/kg. The voltage is 540V.

More practical for the average user than figuring out density is knowing the end weight of the packs. There are two SI packs available. The SI60 holds 60 kWh of energy and weighs 360 kg (790 lb) and the larger SI90 hold 90 kWh and weighs in at 540 kg (1190 lb).

ExploMar uses a rating I have not seen on a battery before: Cruising Efficiency, a measurement of the amount of energy used per distance travelled and expressed as: kiloWatt hours / kilometre. The rating can never be exact, because the final result depends on the total weight of the boat, the water and wind conditions and what is considered ‘cruising’ speed, but it is an easily understood guideline. The company says the Cruising Efficiency of the SI60 is 1 kWh per km (.63 mi / .45 Nm) and the CE of the SI90 is 1 – 2.5 kWh/k (1.6 mi / 1.4 Nm).

The packs for ExploMar single outboard motor systems can be configured with SI units of up to 270 kWh capacity. The company has also worked with boat builders on vessels with multiple outboards. A dual-motor system can double the storage to 540 kWh, and a four-motor system can achieve a total energy capacity of 1,080 kWh.

High speed charging and discharging

The C rating of a battery is how quickly it can transfer energy – both discharging and charging. (A larger number is faster: A 2C battery has a half hour discharge time, a 1C battery has 1 hour, and 0.5C a 2 hour discharge time.) The C rate is partly determined by the battery, but also by the motor the energy is being delivered to and the system the battery is charging from. The Super Island batteries support 1C to 2C high-discharge rates and are compatible with 400V and 800V voltage stations.

As Jonathan Wang, Sales Director of Explomar says, “For electric boats, the battery is the heart. The SI modules not only meet the high-frequency usage demands of work and leisure boats but also make the full electrification transformation of traditional, high-fuel-consumption vessels, such as medium-sized ferries, a realistic possibility.”

Victory at Monaco Energy Boat Challenge

The Monaco Energy Boat Challenge is a university student competition started in 2014 that now brings together over 30 teams from around the world who build FFF (fossil-fuel-free) boats and participate in a series of races to explore the future and expand the boundaries of zero emission propulsion technologies.

Since 2021 there has been an accompanying regatta of commercial electric boats at the MEBC with a schedule that includes a race from Monaco to Ventimiglia (Italy) and back – a distance of 16 nautical miles (30 km / 18.5 mi).

For the ExploMar entry they worked with XTenders of the Netherlands on a 6.3 m (20 ft) carbon fibre RIB (Rigid Inflatable Boat) powered by the WAVE 300 (220 kW) system with a 125kWh battery pack – not the SI model but the company’s HEDB (High Energy Density Battery) model that uses semi-solid state technology.

Read: Present and future of e-boating leap fast forward at MEBC 2025

It was an extremely close and exciting race, with the ExploMar/XTenders boat just edging out the Axopar A/Xe 25 with an Evoy 300+HP mere metres from the finish line. With a time of 29 minutes 8 seconds that’s an average speed of about 33 knots (61 kph / 38 mph), and the boat still had about 50 kWh (40% of capacity) in the battery, ready to go out on the water for more.

ExploMar electric outboards X Aqua high speed charging

One of ExploMar’s fellow exhibitors and participants at both the Salone Nautica Venezia and Monaco Energy Boat Challenge was Aqua superPower, the global network of fast marine chargers. They had their 75 kW DC charger in Venice and their 200 kW ultra-fast DC station at the Yacht Club de Monaco, host of the MEBC.

The two venues and chargers provided an excellent demonstration of the seamless compatibility of the Aqua and ExploMar systems and the companies are now partners in their common missions to electrify propulsion for leisure boating, water sports, commercial vessels, passenger transport and aquaculture.

The partnership ensures that all of ExploMar’s outboard systems, with either the Super/Island or HEDB batteries, can be charged at any of the stations in Aqua’s growing network of 59 sites in North America and Europe. The network’s use of the Combined Charging System (CCS) enables real-time monitoring of battery metrics like temperature and state of charge.

As more and more manufacturers like ExploMar join the Aqua network, a cohesive ecosystem is being created that reduces range anxiety and supports diverse applications, from eco-tourism to high-frequency commercial operations.

Cleaner quieter boats for Portuguese whales

To top off their excellent summer, ExploMar announced the launch of an all-electric whale watching boat – the TERRA AZUL EVØ – that will operate in the Azores Islands of Portugal. The boat, made of HDPE (High Density Polyethylene, which is also used in food and beverage containers, piping and cutting boards) and built by Tideman Boats (winner of the 2023 Gussies Electric Boat Award in the Electric Workboats category), is powered by ExploMar’s WAVE 300 with the HEDB 125 high-energy density battery system. (Say that fast three times: ‘the HDPE boat with the HEDB battery‘!)

This setup delivers between 3 to 6 hours of clean, high-output operation on a single charge and integrates ExploMar’s Smart Captain control system to give the boat operators real-time insights into system status for enhanced safety and control on the water.

The initiative was spearheaded by Azores Whale Watching Terra Azul, a dedicated advocate for responsible eco-tourism that combines marine wildlife education with a profound respect for Azorean culture and biodiversity. By replacing traditional combustion engines, the electric boat eliminates engine noise and pollution—two critical factors in protecting delicate marine ecosystems and wildlife.

“The combination of electric propulsion and an HDPE boat is the most sustainable way to go” said Bruno Tideman, CEO of Tideman Boats. “Low carbon footprint, no aging, inert, 100% recyclable and no need for anti-fouling makes this boat the best option for nature sensitive activities.”

Websites of electric boating companies in this article:
ExploMar  Aqua superPower  Tideman Boats  Monaco Energy Boat Challenge Terra Azul