Clyde shipbuilding

Iona II was built on the Clyde, a pioneering shipbuilding area of its day.

Shipbuilding on the Clyde

In the early 1800s, technological developments allowed steam power to be used as a method of propulsion in ships, and the shipyards on the Clyde were leaders in this field. Beginning in 1812 with the construction of the steam boat Comet, the River Clyde was to become the greatest steam and iron ship building centre in the world.

When Iona II’s shipbuilders J. & G. Thomson were first established in 1851 there were six shipyards based on the Clyde. At the peak of this shipbuilding industry, at the beginning of the 20th century, there were over 200 separate yards constructing vessels from cruise liners to warships and yachts to submarines.

Famous ships built on the Clyde include:

• Clipper Cutty Sark (1869)

• Biggest ship in the world at the time RMS Lusitania (1906)

• Battle cruiser HMS Hood (1918)

• Cunard's RMS Queen Mary (1936)

• Royal Yacht Britannia (1953)

• Transatlantic Liner Queen Elizabeth II (1969)

Building the Iona II

The Iona II was an iron hulled paddle steamer built in 1863 at the Clyde shipyard of J. & G. Thomson as a mail and excursion steamer for David Hutcheson and Co. This vessel represented the height of mid-19th century passenger steamers in both technical innovation and luxury. The vessel had a long, thin iron hull of 245ft (75m) length and 25ft (7.6m) in the beam, (excluding paddle boxes), a narrow clipper like bow and reportedly cost £18,000 which is at least £1.5million in today’s currency.


Luxurious passenger accommodation

Clyde steamers were renowned for their creature comforts. However, Iona II surpassed most other vessels. Space was available for both cabin and steerage passengers to dine, wash and walk in surroundings suitable to their station in life. The first class dining room was 70ft in length and fitted out with crimson velvet sofas, gilded mirrors and Ionic columns. There were also ladies and gentlemen’s retiring rooms with washing facilities.

Model of the <em>Iona II<em>

The most notable feature of this vessel was the 180ft saloon which was fitted out in luxurious furnishings for the cabin passengers aft of the paddle wheels and in slightly less grand terms for the steerage passengers in the forward section. Above this was a promenade deck running the length of the vessel allowing passengers to see and to be seen.

Height of shipbuilding technology

The Iona II was powered by steam produced in tubular scotch boilers which operated the oscillating engine which turned the paddle wheels. This was the main form of ship propulsion during the 1860s.

Scotch boiler


The two sets of scotch boilers (illustration on the left, Paash 1885) on the Iona II were made of shaped iron plates riveted together. The forward pair of boilers were 9.2m long and close to the paddle wheels at the centre of the vessel while the aft pair were only 5.4m long and further away.

Each pair of boilers on the Iona II shared a smoke stack which allowed exhaust gas from the furnace to be expelled. These smoke stacks are an iconic feature of steam vessels.

While there were many different types of scotch boilers, they all basically worked in the following manner.

·         * Coal was burnt in the firebox at the base of the boilers producing great heat

·         * Hot gas from the firebox passed through tubes in the boiler, heating the water until it turned into steam

·         * An additional feature of the Iona II was a super-heater that further heated the steam and increased the efficiency of the boiler

Drawing of the Iona II's engine

·        *Steam was then directed into the engine (shown on the left, Griffiths 1993) to operate the machinery before condensing back into water for the process to start again

Iona II demonstrated the peak of 19th century shipbuilding, particularly in its state of the art oscillating or reciprocating engine of 150 horsepower. Due to its superior engine, the Iona II reportedly reached 24 knots during sea trials which was almost 10 knots over the average paddle steamer speed of the day.

The oscillating engine received steam from the boilers through the high pressure (HP) intake valve which controlled when steam was allowed into the HP cylinder. The steam forced the HP piston up and down which turned the crankshaft via the connecting rods and rotated the wheels with the feathered paddle floats. Used steam was exhausted from the oscillating HP cylinder to the low pressure (LP) cylinders via another valve, to be reused, before being finally exhausted to the condenser.

The connecting rods for the high pressure and low pressure valves can still be seen on the crankshaft but the cylinders are now buried.

The boilers and engine provided the power, but it was the 20ft diameter paddle wheels that actually propelled the Iona II through the water. The two paddle wheels on either side of the vessel had patent ‘feathering floats’ which were variable pitch paddle blades which allowed the angle of the blades to be adjusted, or even removed where appropriate.

J. & G. Thomson Shipbuilders

Iona II was built by J. & G. Thomson Ltd., one of the foremost shipbuilding companies of the time. The brothers James and George Thomson were apprentices to ‘the-father-of-shipbuilding on the Clyde’, Robert Napier. In the mid-1800s, the brothers ran an engineering works at Finnieston on the north bank of the River Clyde. 


In 1851 they branched out into shipbuilding with the opening of a yard at Bankton on the south bank of the River Clyde. Within their first year, the Bankton yard occupied a space of about 3 acres, employed 200 workers and built the paddle steamer Mountaineer which was bought by David Hutcheson & Co for the West Highland trade. J. & G. Thomson specialised in iron paddle steamers particularly those of the luxury, passenger carrying type, such as the Iona II. They built vessels for use in the British Isles, Europe and Australia and also built over 40 liners for Cunard.

During the 1860s, up to 14 of the vessels that came out of the Thomson yard were destined for the American Civil War. Some of these vessels were built as river steamers and then sold on by local shipping agencies at high prices to the Confederates while other vessels were purpose built for the conflict.

Converted river steamers: PS Adela, PS Iona I, PS Iona II, PS Fairy, PS Havelock, PS Giraffe, SS Fingal, PS Venus

Purpose built: SS Pampero, SS Lilian, Ironclad Danmark, SS Emma Henry, SS Little Hattie, SS Wild Rover

During this fruitful shipbuilding period, James Thomson took early retirement and left his brother George to continue on the business. Unfortunately, George Thomson died in 1866 and it was left to his two sons, also called James and George to run the business.

In 1872 J. & G. Thomson Ltd. were forced to sell their property to the Clyde Navigation Trust which needed more dock accommodation. The location of the Bankton yard is now occupied by the Glasgow Science Centre and Tower.



In 1872, the shipbuilding business was forced to move downstream to the junction of the Rivers Clyde and Cart by the expanding Clyde Harbour Trust.  The location of the new shipyard was where the River Clyde joined the tributary River Cart which created a large tidal basin allowing very large ships to be launched.

Despite severe financial difficulties during this period, the company developed a reputation based on engineering quality and innovation for their vessels and high standards for workplace facilities. The building yard and engine works came to occupy an area of about 50 acres and, when fully engaged, employed from 3,000 to 4,000 men. Over the beginning of the 20th century, the shipyard built up a community around the facility which went on to become the township of Clydebank.

In the 1880s the company began the transition from iron to steel construction for vessels. Also at this time, J. & G. Thomson Ltd. built several record breaking vessels including the brig rigged twin funnelled America that won the Blue Riband several months running. During the 1890s, the company developed a high reputation for building short-sea packets with eight built within six months. However ship orders began to decrease in numbers and so in 1897 the family company sold the yard to John Brown and Co, Sheffield, steelmakers who continued to build ships in the yard until it folded in 1971.

During the 120 years of this leading shipbuilding company, 744 vessels were constructed, many of them making a distinct mark on history such as the RMS Queen MaryQueen Elizabeth II and PS Iona II.