Stockholm-based X Shore has secured investment of 15 million euros to scale up production of its battery-powered leisure boat.

The company’s 8m long Eelex 8000 went on sale in the US last month, but X Shore is struggling to meet strong orders from its small Stockholm factory. The start-up plans to use the funding to open a second site and increase production to about 400 boats a year, Chief Executive Officer Jenny Keisu said in an interview with technology research organisation IDTechEx.

“What is happening now in the boating market is what has already started in the car industry,” Keisu said. “We have more demand than we can supply and that’s why we are raising capital.”

While the market for electric leisure boats remains small, around 15,000 vessels were sold last year, it’s expected to increase to 70,000 this decade.

Growth is “slow and steady,” and driven mainly by technology improvements and environmental enthusiasts, according to IDTechEx senior technology analyst Luke Gear. It’s held back because the emissions rules and purchasing subsidies that have helped drive electric-car sales don’t exist for the ship industry, he said.

But cities including Amsterdam and Venice have moved to ban or limit the use of petrol and diesel-powered boats. Norway, a global leader in adopting electric cars, earlier this year reaffirmed plans to ban emissions from vessels in certain fjords by 2026.

“It’s hard to say how big this market will become since it’s growing so fast,” said Keisu, “And it’s only fairly recently that there has been a better understanding of how much emissions leisure boats produce.”

X Shore was started by Swedish tech entrepreneur Konrad Bergstrom in 2016 and previously raised money through crowd funding. The latest funding round was led by technology investor Team Europe.