Like many minesweepers, she was constructed of nonmetallic material (fiberglass) in order to reduce her magnetic signature.
Photos taken just after the collision appear to show that the 50,000 dwt Launceston struck Kallisto amidships on the port side and cut her in half. Kallisto's back deck and stern drifted away and sank, and the surviving forward half of the ship took on a heavy list.
Long term followers of this account will be under no illusions as to the bad things that can happen when military vessels tangle with commercial shipping.— Dreadnought Holiday (@TheDreadShips) October 27, 2020
I think we can assume the captain of HS Kallisto here is not a fan. pic.twitter.com/OpwIcDqKmz
For reference, in happier times HS Kallisto looked like this.— Dreadnought Holiday (@TheDreadShips) October 27, 2020
You'll notice it's a lot longer.
The collision with Maersk Launceston has essentially severed most of the ship behind the funnel. pic.twitter.com/UgWijvWZFM
There are two bits of good news.— Dreadnought Holiday (@TheDreadShips) October 27, 2020
Firstly only two people were injured, apparently neither seriously.
Secondly the MoD is trying to flog the identical HMS Atherstone and might just have found a buyer.
I'm sure the crate of port now headed to Maersk's HQ is a coincidence... pic.twitter.com/P0otlm0seC