Navy faces tough test finding out what caused reported gauge failure on submarine, ex-commander says

The depth gauge on a Royal Navy nuclear submarine which reportedly descended towards dangerous depths, could have failed for a "variety of reasons" including because of its age or maintenance issues, a former submarine captain has said.

Commander (Ret'd) Ryan Ramsey told Forces News that "submarines are inherently complex pieces of equipment that operate in a void that’s less explored than space and things do go wrong".

The incident on board the unnamed Vanguard-class submarine, which carries Trident ballistic missiles - the UK's nuclear deterrent - happened more than a year ago, according to The Sun.

• Royal Navy nuclear submarine dived towards 'danger zone' after malfunction - reports
• Deep dive into the Dreadnought-class Trident nuclear submarines
• From Jolly Jack Tars to the Wooden Walls: Royal Navy nicknames explained

Cdr Ramsey explained the narrow escape could have been caused by "a failure in a piece of equipment due to age, it could have been because of maintenance issues.

"It will be really difficult to work that out but the Navy will conduct a very thorough investigation and hopefully learn the lessons from this".

According to reports, it was the vigilance of the crew that averted a catastrophe when engineers spotted a second gauge.

Cdr Ramsey said: "There are processes in place in order to monitor equipment and maybe along the way, that’s failed.

"Things do wrong in submarines but that particular event where the depth gauge has failed, I think in 23 years of operating in the submarine service, I saw that twice."

At least one British submarine carrying nuclear weapons has been on patrol continuously since 1969.

The UK has four Vanguard-class submarines but currently only two are operational, with some of the technology onboard the submarines said to be between 30 to 40 years old.

Cdr Ramsey points out that as the submarines are getting older, so too are the patrol lengths getting longer, which makes maintenance hard.

He said: "Recently I read that one had just done in excess of 165 days at sea and during my time in the submarine service that would never have been the case.

"You don’t have enough facilities and you don’t have enough people and therefore it takes longer in order to do the maintenance and refit.

"One extra bit on top of that, as submarines age, equipment availability becomes less because technology moves on and that also plays a part in how they do effective maintenance."