Launching and recovering large heavy boats without a crane

Hard to tell properly from that piccie...

 

Hydrolift... that was the word i needed

 

That Hydrolift appears to be a graving dock with caissons that fold down to the sea bed to open it when the water level is the same inside and out.
Have a look at this brochure for the Syncrolift -
http://www.ttsgroup.com/Global/Brochures/TTS_Shipyard Solutions_Syncrolift.pdf

This was originally developed in the late 50's by an American Company called Pearlson Engineering - they are still going strong, but they specifically mention on their website that they have nothing to do with Syncrolift now.
Rather, theirs is now called the Pearlson Shiplift.
Home - Pearlson Shiplift Corporation https://www.shiplift.com/

I guess that maybe they 'fell out' with the Syncrolift folk at some stage, as I remember the back cover of the Naval Architect magazine in the 80's almost always had an advert for Syncrolift Systems and Pearlson Engineering.
Edit - Here they mention their history - they went their separate ways in 1990, and then in 2008 Pearlson got back into the Syncrolift field again.
Our History - Pearlson Shiplift Corporation https://www.shiplift.com/our-heritage.html

 

Yes, essentially they did that at Huskisson with the Lady Denman- she's been moved again into a concreted dry doc and now inside a building... a "Land dock" similar to building canal estates so essentially the caisson is dirt. There's also "slave docks" which generally require a graving dock or other mechanism on small scale such as a travel lift- just a barge with the boat upon it...
Docking of submarine on slave dock in Big Dock 4 October 1974 | The Dictionary of Sydney https://dictionaryofsydney.org/media/4374

Both the tall ship James Craig was and the steam ship John Oxley currently being restored on slave dock Home - SHF - John Oxley https://johnoxley.org.au/#
Jeff.