Maritime drones appear to be gaining traction, and I'm indebted to YouTube channel 'One Wingspan Above' narrated by a New Zealander (?) with a voice that's ideal for drifting off to if you're struggling. He highlights three newish projects among many that are falling over themselves to ensure the sea is littered with drones as well as land and sky.
Top left is Levanta, who've invented what they call the 'hover foil' or hydrofoil with a dome-shaped outline into which they pump air to raise it to the surface. Though it's an imaginative leap and does what it says on the tin, I would suggest that hydrofoils do anyhow get craft up there fairly sharply once underway. They also suggest theirs is the first float-fly-float drone ever, though quads with floats for alighting on water date back practically to Roman times. Nonetheless, wish them luck and Godspeed.
Also out there in the US is Poseidon, at bottom left, based in San Fransisco instead of Missouri and counting among its staff any number who've worked on Amazon's delivery drones... and therefore not to be sneezed at. They are pioneering more of a regular seaplane that could nonetheless be controlled by computers to stay within the regime of ground-effect in order to do more for range and endurance. There is nothing new here besides, but often that's the key to success: Regent's sea-glider has been pranged from time to time endeavouring to manage the hairy intersection between hydrofoil lift and aerofoil.
Finally there is Airship, which draws upon the reverse wing layout pioneered by the same guy who did the same for delta-wings during WW2... but which like so many other WIGs (wing-in-ground effect and not the hairpiece) never took off, or at least figuratively.
The number one reason I can see for the failure of ground-effect efforts in the past is that (a) if they were boat-shaped they only worked on smooth seas and (b) if aeroplane-shaped, kept catching a wingtip on the waves before crashing... which seaplanes and flying-boats have done since time immemorial.
The one thing I want you to take away from this being that this is why my boat is boat shaped, but boat-shaped in a way that does not exclude flight in ground-effect due the potential to make it a fraction of the weight of traditional watercraft, beside enjoying advances in electrical propulsion ~ print that out and put it where it can be seen when you wake each morning.
But back at Airship ~ suspect PR as it instantly conjures up images of people falling to their deaths from a burning Zeppelin ~ the takeaway from this is that the private sphere works best in the US, but only really the public sphere in Europe. What that means in effect is that in the former small teams of individuals can develop projects and then source funding from VCs for a leg up, whilst in Europe they are destroyed by regulation and bureaucracy before being sold off like Lilium and Volocopter to the Chinese... who also know how to develop and industry.
Accordingly Airship is a cross-cultural effort amongst a variety of universities around Europe, funded by the EU over cappuccinos in Brussels. It is unsurprising then that unlike Dr Lippisch's clean-lined prototypes, it looks like ground-effect-by-committee.
So meantimes we plough our lonely furrow here, don't we Gromit?
And now if you'll excuse us, we've a toilet to fit.