Yachts aren't the only ships on the oceans which might need rescue. Consider a similar scenario with a fishing trawler stranded at sea instead of a yacht.

It's possible to do a cost-benefit analysis, but it's not meaningful if it only takes into account adventure yachtists.

What about fishing boats which have been hit by freighters (as in http://gcaptain.com/dutch-freighter-sinks-french-trawler/ )? Do the owners of uncrewed freighters have no culpability or responsibility in helping contribute towards a safety net even though the freighter might be the cause of a problem?

Freighters themselves also have problems at sea. Eg, http://worldmaritimenews.com/archives/68327/vietnamese-freig... concerns a freighter where 18 of the crew were rescued by another freighter, the Pacific Skipper.

Here's a case where a cargo ship hit a ferry - http://edition.cnn.com/2013/08/18/world/asia/philippines-shi... . The crew of the cargo ship, plus the navy, Coast Guard and other commercial vessels, worked to rescue some of the passengers. If commercial vessels were uncrewed then that's fewer ships that could have helped.

> If commercial vessels were uncrewed then that's fewer ships that could have helped.

It's also vastly fewer ships that could end up in trouble with crews that will need to be rescued.

First, that's a conjecture. It assumes that uncrewed ships will be safer. (Eg, it may end up colliding into other ships more often.)

Second, you don't know what you are talking about, because there's no way to get "vastly fewer ships".

There are some four million fishing vessels, of which 1.3 million are decked and about 40,000 of them are longer than 24 meters (over 100 tons). These are not going to be uncrewed because we haven't automated fishing.

According to the CIA factbook at https://www.cia.gov/library/publications/the-world-factbook/... there are 16,406 vessels in the world's merchant marine. Of those, over 1,722 (I stopped counting at Norway) are passenger or passenger/cargo ships which cannot be uncrewed.

Removing the crew from the 14,000 remaining ships is not going to "vastly" reduce the number of ships with crews that will need to be rescued. It will, on the other hand vastly reduce the number of ships with the capacity to help in an offshore rescue. (A commercial troll vessel with a crew of 4 doesn't have the extra safety equipment that a, say, Handymax bulk carrier carries, and can't handle the same weather conditions.)