Banner source: image taken by Donna Cooke from Poole Quay

NAS member Karen Moule has been diving for over 30 years and has always had a love of diving on shipwrecks. Since attending NAS’s online course on Metal Shipwrecks, it has given her a whole new appreciation for them.

Understanding & recording metal shipwrecks part 2- Day on SS Shieldhall 26th June 2021

Following on from the one-day online course on metal wrecks, Jane Maddocks was our tutor and Cat Holt our host for the day for our practical session. We all met on the dockside of Dock Gate 10 at Southampton Docks, where SS Shieldhall was moored up.

Image. Jane Maddocks (left) and Cat Holt (right) at the practical metal wrecks course.

SS Shieldhall’s background

This ship was chosen because she is a unique time capsule - providing a working example of steamship machinery, typical of the cargo and passenger ships that plied the oceans of the world from the 1870s until the mid-1960s.

Built on the classical lines of a 1920s steamer with a traditional wheelhouse, Shieldhall weighs in at 1,753 gross tons, has a length of 268ft and a beam of 44ft 6”. She has two triple expansion engines with two large, oil-fired boilers providing steam power throughout the ship. The hull is of riveted and welded construction and this unusual feature is representative of the transitional phase in British shipbuilding when welding took over from riveting. The hull has a slightly raked bow and cruiser stern. The teak decks and emergency steering position aft add to the classic effect. Shieldhall was effectively obsolete mechanically at the time of her launch having steam machinery representative of the late 19th century at a time when the diesel engine was coming into its own.

She launched on 7th July 1955 and was operated by Glasgow Corporation to transport treated sewage sludge down the river Clyde to be dumped at sea. She also continued a long tradition, dating back to the First World War, that Glasgow’s sludge vessels offered disadvantaged families and wounded or disabled ex-servicemen and women free day trips down the river in the summer months.  This meant that Shieldhall was built with a large saloon and facilities to accommodate up to 80 day-passengers on trips down the Clyde.

Images. Author sitting at the bow (left) and ship's bell (right)

Shieldhall finally finished 21 years of service in 1976 and is now believed to be the largest working steam ship in Northern Europe. She is owned and operated entirely by volunteers.

So, what were we doing for the day?

Jane wanted us to explore the ship, recapping on our online learning, identifying the elements we had covered in the online course, locating them, then creating ‘quick & dirty sketches’ of three parts of the ship: the bow, the funnel and the stern.

Splitting into three groups, we started our observations and sketching, taking approximately 20 mins in each area of the ship and then regrouping to discuss our findings and what deductions we could make about the ship.

Images. Author's sketch of the bow (left) and photo of the steering quadrant (right)

Following on from this, we then needed to identify the ‘deck furniture’ that would help with running the ship, how it would stay secure when moored and clues about the purpose of the ship.

After lunch, and staying in our groups, we took it in turns to visit the boiler room. The minute I stepped in the door, the temperature was immediately tropical and humid. The noise was immediate too, with near shouting required to communicate with each other.

Image. View of the machinery room from above.

As I descended the steps the triple expansion engines were right below me on either side. At the bottom of the steps the pistons turning the propeller shaft was an impressive feat of mechanical engineering to see. The narrow gangway led me between the insulated boilers to the back of them, where a multitude of gauges told the heat-resilient volunteer team exactly what was going on. I could see the white-hot furnace inside the boilers, which was almost blindingly bright.

It had taken most of the morning to get the boilers up to temperature, and now that we were steadily cruising, the team would be in this ‘oven’ for the next 3-4 hours!

Images. Volunteer in the engine room (left) and course participants below decks (right).

Boiler & engine technical details

Two Scotch boilers, each 12ft diameter and 12ft long, produce saturated steam at a pressure of 180lb/sq.inch. The steam powers the main engines, auxiliary engines, all the deck machinery and a 25kW electrical generator

The boiler is of riveted construction and has approximately 320 firetubes. Fuel oil is forced under pressure to provide an atomised spray which is then burnt in the furnace. Air for combustion is supplied by a single cylinder, forced draught fan. To improve efficiency, the air is heated by the combustion gases before they exit from the funnel.

The two main engines were constructed by the ship’s builders, Lobnitz & Co., of Renfrew, Scotland. The triple expansion engines have cylinder diameters of h.p.15″, i.p. 25″ and l.p. 40″, and the stroke of 30″. Each engine can provide up to 800 horsepower to its screw. The normal service speed is 9 knots at 86 rpm. This is an economical speed, although the designed maximum is 13 knots at 120 rpm.

Waste steam from the engines, is ejected to a condenser where it is cooled by sea water passing through the heat exchanger tubes. The condensed steam is held in the hot well before being pumped back to the boilers as feed water.

Seeing all the different parts of a ship on a live working version will really help with my future orientation on sunken ships and give me an improved chance of identifying elements of a shipwreck even if they have been damaged or are in different locations to where they should be.

This was a real treat of a day, which made me think of the passengers who were fortunate to have free trips when this was a working steamship. It must have been a real treat for them too.

Find out more about SS Shieldhall here and please feel free to make a donation to keep this ship in service.

Technical details, courtesy of the website.