Re: Where's the advantage?
> How exactly will recharging by docking with the underwater part of a surface ship help matters?
Imagine the Bad Guys are watching from another ship, a plane, a spy satellite, or from the shore. If you pull the sub out of the water, the Bad Guys will see it. If your sub stays underwater and just comes close to the ship - or close to the charger on a long cable lowered by the ship - then they Bad Guys won't see it.
Maybe you're doing secret spy stuff and you want to hide the fact that you're using the sub at all, so you launch it when the Bad Guys aren't looking and keep it submerged. Or maybe if the sub is part of your defenses you don't want the Bad Guys to know when it's off-duty and recharging, because that would be a good time to attack.
Perhaps you just want to keep the sub in service as much as possible, and hauling it out to charge it takes time. Or perhaps it's bad weather so hauling it out stresses the sub and crane and is dangerous to the crew, so you don't want to risk it unless you really have to. Or perhaps it's very bad weather so hauling it out is impossible, but charging on a submerged charger with a long cable is possible.
Having said all that, I don't know why they're not just looking at underwater power connectors for wired charging, but I guess that's tricky too. Maybe they are looking at that too, and just chose to speak about the wireless one. Or maybe they've already looked and decided it's not practical.