Star Canopus diving accident

The Star Canopus diving accident was an incident in Scotland in November 1978 that killed two British commercial divers.

Despite the efforts of three rescue vessels – Intersub 4, Tender Carrier, and Uncle John – the bell was not recovered for over thirteen hours, by which time Ward and Prangley had died of hypothermia and drowning.

[citation needed] Oil production had declined that year,[5] and with winter conditions upon them, subsea work had fallen behind schedule.

[6] There was "a lot of catching up to do", Martin Dane, the Contracts Manager for Northern Divers would say later,[7] and Mobil Oil, like many operators, decided to allow the diving program to continue through the winter months to take advantage of available weather windows.

[12] The Canopus was only a year old, and although it represented the latest and best technology of that era, the limits of her dynamic positioning system were 18–20 knots with the wind hitting her broadside.

[citation needed] Kelly determined the weather was suitable for diving and, at 0240, he launched the bell with Tony Prangley and Michael Ward inside.

Then, at 0545, the wind suddenly shifted directions and began blowing from the north at a speed of 40 knots, hitting the Canopus on her beam, and overpowering her dynamic positioning (DP) system.

On the surface, the force of the wind had blown the Canopus sideways against the platform overhang, snapping off the ship's mast which came crashing down onto the deck.

Captain Forsyth quickly took the ship off DP and tried to swing the bow outboard to keep the vessel from grounding on the submerged pontoons of the Magnus.

[citation needed] In dive control, Kelly was waiting for Prangley and Ward to seal the bell when the red 'Dive Abort' indicator suddenly lit up.

When the bell was 30 metres (98 ft) from the surface, Prangley suddenly stood up, waved his fist shoulder high, and shouted, "All stop.

The bell umbilical and clump weight guide wires were not hanging straight down through the moonpool; they were leaning towards the bow of the ship.

However, Prangley and Ward could not release the weight because it was externally secured to the bell frame with a set of "secondary locking pins".