The relevant phrase is underway replenishment (aka UNREP) https://en.wikipedia.org/wiki/Underway_replenishment

It's been the basis for at-sea supply of long-endurance ships since ~1910 when refueling oil became a key blue sea naval requirement.

Modern example: https://m.youtube.com/shorts/kzncvGBj-88

Mostly tensioned cables carrying hoses (liquids especially fuel being the highest volume / limiting factor), some palletized transfer over cables, and some helicopter lift (because the flight pads/decks are already sitting next to each other while everyone is waiting for fuel to finish).

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Tangurena2 13 hours ago | parent | next [-]

I've watched some videos showing UNREP and they're fascinating. It takes a lot of skill to keep the ships parallel. There was a collision earlier this year between the resupply ship and the recipient.

Analysis:

https://www.youtube.com/watch?v=zSYl9y3e944

Also, the Navy is using Ospreys to resupply submarines at sea because they have the range and helicopters don't.

	▲	ethbr1 11 hours ago \| parent [-]
		> Also, the Navy is using Ospreys to resupply submarines at sea because they have the range and helicopters don't. Afaik, modern submarines handle terribly on the surface, so I imagine direct ship-to-ship UNREP is rare. Also, too much cost risk from a collision. Per YouTube, it's mostly vertical replenishment. Helicopter for short range. Osprey for longer. Floating pallets pushed out of the back of a C-17 at max range. I'm sure the packing is intricate for something that's going to be air dropped, then floating, then has to be broken down on an unstable floating platform and conveyed inside through small ports!

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ericmay 11 hours ago | parent | prev [-]

Spot-on and thanks for sharing that video too. Aircraft carriers aren't really designed to be replenished by large aircraft which would instead be used to replenish sites like Guam with large enough runways and, frankly, the need if something went wrong due to the population size, remoteness, and inability of everyday residents to do anything about the situation.