We've all seen articles about massive container ships of the future using kites to supplement their engines, but I suspect a really solarpunk future would look a bit further afield, or perhaps further back in time for their ship designs.
I think in any future with humans and continents, people are going to be trying to cross the ocean. There might be less shipping in a world without our abundance of cheap energy, or more of a focus on reducing consumption and producing necessities locally, but people will still trade goods and travel. So what might the ships look like? Return to tallships? Solar panels and electric motors? I love reexamining traditional technologies to see how they can fit with modern engineering and design principles, safety features, and electronics, but I don't know much about ships, and especially not much about modern sailing.
So what do you think will be bringing back holds full of old world fashions harvested from the Chilaen desert?
Helium leaks just as much as hydrogen.
I think an easy solution to that is to put a neutral gas like nitrogen in an intermediate layer between the hydrogen and the air. That way there's no contact between hydrogen and oxygen gasses in the event of a tiny puncture. And the leaked hydrogen can just be replaced by freshly electrolyzed hydrogen from water, made with solar power in the mechanical room of the airship.