USS Monitor

The USS Monitor was a revolutionary iron-hulled steam warship, designed by John Ericsson.

General

The Monitor, the first iron warship commissioned by the United States Navy, was built during the American Civil War as an urgent response to the Confederacy's construction of the ironclad CSS Virginia (based on the former wooden steam frigate USS Merrimack). Monitor became famous for her central role in the Battle of Hampton Roads on 9 March 1862, where, under the command of John Lorimer Worden, she fought the Virginia to a standoff.

'Iron Dawn' by Richard Snow provides an excellent account of the background to the politics and construction of Virginia/Merrimack and Monitor, and gives graphic accounts of their actions at sea. The book, along with the excellent Wikipedia entry, provide much of the following information.

The impetus to build an ironclad in 1861 came from the Secretary of the Navy, Gideon Welles and Cornelius Bushnell (a 'venture capitalist' in today's terms). They established an Ironclad Board. Bushnell was introduced to Cornelius Delamater, who in turn brought his friend John Ericsson into the frame. Ericsson was endowed with quite remarkable ingenuity, engineering knowledge and dynamism. He was by no means bound by convention. He was also dogmatic and hot-tempered.

Ericsson produced a preliminary proposal for a novel all-iron vessel whose hull was nearly submerged, and which carried a single cannon in a revolving turret. At the end of August 1861 he wrote direct to Abraham Lincoln with his proposals. Lincoln apparently did not see the letter, but Benjamin Isherwood did, and rejected the idea. It should be noted that Ericsson's standing with the government had been tarnished by technical failures which were, rightly or wrongly, laid at his door. However, following Bushnell's intervention, Ericsson was ordered to proceed, and construct a vessel within a remarkably tight timescale. Just 100 days were proposed for the design and construction of a warship bristling with novel features. There was endless scope for things to go wrong, and, as it turned out, there would be no time to make significant changes if fundamental problems had arisen.

A partnership was formed, with Bushnell and Ericsson sharing a half interest, and John Winslow and John Griswold the other half (Winslow and Griswold were partners in the Rensselaer Iron Works and the Albany Iron Works). Ericsson was to be in charge of the design. His chief draughtsman was Charles MacCord.

The armour plates were produced by H. Abbott and Sons of Baltimore. The gun turret was made by the Novelty Iron Works of New York. The low-profile trunk engine, made by the DeLamater Iron Works of New York, incorporated several novel features. The hull was constructed by the Continental Iron Works. The two guns were designed by John A. Dahlgren. Ericsson wanted 15-inch guns, but he had to settle for 12-inch, and finally 11-inch. Even then, they were to be limited to a charge of 15 lbs of powder, rather than the 30 lbs for which they were designed.

The turret was 9 ft high and its internal diameter was 20 ft. The cylindrical part was assembled from 1-inch plates bolted together to the thickness of 8 inches, increased to 11 inches at the gun port area. At rest, the turret rested on a smooth ring of 'composition metal', but when being rotated it was raised by a wedge under the central spindle's bottom bearing. A large spur gear mounted on the spindle engaged with a train of gears driven by a small steam engine.

The hull was launched on 30 January 1862, without the gun turret. The 120-ton turret was installed soon after, and was first rotated using steam on 17 February. The vessel first moved under steam on 19 February.

On 8 March, the CSS Virginia engaged with warships of the US Navy, with devastating effect, sinking the Cumberland and destroying the Congress. Virginia was seen to be practically invulnerable, with nothing to prevent it proceeding to Washington and laying the city to waste. Panic ensued.

Prepared for action, Monotor headed south on 6 March, proving very stable in calm water. On the following date, rough sea conditions were enountered. The hull sat very low in the water, offering adversaries little in the way of a target. There were obvious risks in having such a small frreboard. Ericsson had intended the turret's circular base to be sealed, when not required to rotate, by metal-to-metal contact. However, mechanics at Brooklyn Navy Yard had seen fit to insert a gasket of hemp rope. In the rough sea, the penalty of the low freeboard made itself felt, and water readily found its way through the turret seal, soaking any crew in the vicinity. In the separate armoured wheelhouse, the helmsman was battered by water forcing its way in through small openings.

As the seas became heavier, water found its way into the short funnels and into the air intakes for the centrifugal fans which provided air for the boilers and for ventialtion. Worden had previously raised concern about the height of the funnels, and Engineer Stivens had criticised the height of the air intakes, at just 4 ft above the deck. Inevitably, Ericsson had been unreceptive to the criticisms.

Incoming water was sprayed around by the fans, drenching everything including the fans' drive belts. The blowers stopped, and the boilers were starved of air. Steam pressure fell. The main and auxiliary engines lost power. Carbon monoxide from the furnaces started to accumulate. Crew members began to lose consciousness or passed out. Others bravely went down to rescue them. Alban Stimers made repeated returns to the engine room after short breaks to breathe fresh air.

Monitor was taken in tow by one of the accompanying vessels - the Seth Low - and towed to calmer waters near land, and normal conditions were restored. On returning to rough conditions, Monitor was in trouble again, both with the blowers and with the rudder's controlling ropes jumping off their guides. Again, the Seth Low towed Monitor to calmer conditions. Later, conditions improved, and Monitor continued to head towards Chesapeake Bay, while the crew set to work dealing with the effects of corrosion which resulted from the ingress of seawater, causing seizure of various parts of the machinery and guns. Monitor picked up a pilot, who provided news of the Virginia/Merrimack's exploits, with the warning that Virginia's destructive work would continue with the daylight and favourable tide. The USS Minnesota, 44 guns, stuck on a mudbank, was at risk of destruction by Virginia, and Capt Worden decided to go to her aid. Minnesota's captain was by no means reassured by the sight of this curious semi-submerged vessel with just two guns.

In Action

Monitor and Virginia were engaged in a 4 hour duel on 9 March. Neither ship sustained major damage.

Following the engagement, it was determined that Monitor had been hit 22 times, including nine hits to the turret and two hits to the pilothouse. She had managed to fire 41 shots. Virginia's armour sustained 97 indentations from the fire of Monitor and other ships. The capability of both ships' armamament had been constrained: Virginia's by the limited availabiity of solid shot, Monitor's by restrictions on the amount of charge allowed to be used.

Overview

The achievement of Ericsson and all concerned in designing and constructing this novel warship in little over 100 days is astonishing.

Claims were made for the novelty of many of the features. Not all of them stand up to scrutiny, but it is not proposed to examine them all here.

It is often stated that as a result of the Battle of Hampton Roads in 1862, the navies of Britain and France halted further construction of wooden-hulled ships. This is misleading. They were already locked in an arms race following France's laying-down of the ironclad Gloire in 1858. By the end of 1861 France had laid down sixteen ironclads, while Britain had laid down ten and ordered the armouring of another nine wooden ships then under construction. Most of the early ironclads had wooden hulls protected by armour, but HMS Warrior, ordered in 1859, was all iron. Wooden warship construction continued in parallel, while non-armoured iron ships were also being built, in recognition of both the advantages and disadvantages of iron hulls compared with wood, and in the light of accumulating experience with iron hulls. Only by the mid- 1870s had wooden warship building ceased in Royal Navy Dockyards.

Curiously, an aspect of the design of Monitor's rival, CSS Virginia (Merrimack) which had a marked influence on the world's navies, was the provision of a ram.

Gun Turrets: Theodore Ruggles Timby had patented a revolving gun turret in the USA in 1843. Much to Ericsson's annoyance, his business partners initially paid Timby a royalty for the use of gun turrets.

Capt. Cowper Phipps Coles in the UK had started to develop gun turrets for ships in the mid 1850s, and in early 1861 his design for an iron ship with turrets, sloping armoured upper works, and double-walled iron hull was described and illustrated in 'The Engineer'. However Ericsson claimed to have perfected the invention more than seven years before Captain Coles brought out his 'abortive scheme'. This claim presumably relates to the scheme he offered to Napoléon III in September 1854, but no record of any such submission has been found. Coles had started with an ad hoc arrangement of a cannon on a raft during the Crimean War in 1855. He soon followed this with another raft, which was provided with hemispherical iron shield over the gun. In late 1861 he had fitted a revolving gun turret to HMS Trusty. With a view to deflecting shot, Trusty's turret was in the form of a truncated cone. The trials of Trusty's turret were very widely reported in the press in the autumn of 1861. At that time the British Admiralty were clinging onto the use of sail, and a penalty of the turret's success at deflecting projectiles was consequential damage to the ship's own masts and rigging! No such problems for Monitor or Virginia.

Captain Worden, as he bravely headed into close-quarters battle with Virginia, would have been all too aware of of Virginia's success against well-armed wooden warships, and of Monitor's own shortcomings. He had already experienced the effect of having such a low freeboard in heavy seas. He was unhappy about the lot of the helmsman in the pilot hose, a square structure made from rectangular iron slabs, bolted together and interlocking in the manner of a log cabin, a shape not conducive to deflecting shot and shell. He was more concerned about the slow firing rate, and the vulnerability of his armament: just one pair of guns in a single turret, whose cylindrical shape made it vulnerable to direct impact.

Details of Construction

Some of the Monitor's artefacts have been salvaged and conserved, including the turret, guns, engine, condenser, Worthington pump, and many smaller items. See USS Monitor Center website here.

Photographs of (inverted) turret here. This photograph in particular indicates how the cylinder of the turret was assembled from numerous wrought iron plates having their long axis vertical. Each layer appears to comprise about 24-26 individual plates. The edges of the plates butted together, and the butt joints were offset between layers. The layers of plates were held together by numerous bolts. The inboard ends of the bolts and their nuts were originally covered by thin plates, perhaps to prevent injury if the gun crew were thrown against the sides. Bolted iron rings at the top and bottom were not covered, presumably being out of harm's way. Alternatively the thin covering plates might have been fitted to reduce the consequences of nuts and bolts flying out due to impact. There appear to be seven layers of plate near the camera, plus a thinner ring which protrudes beyond the others. This seems to be a continuous ring, fairly short in height. Was this part of the sealing arrangement?

The photograph shows the roof of the turret comprising a grid of iron bars (including railway rails). The grid receives some support at mid-span from struts connected to a forged bar at the bottom of the turret. The photograph also shows the coffin-shaped pivoted blocks used to cover the gun ports.

This high resolution contemporary photograph shows that the outboard ends of the turret plates' bolts were countersunk and peened to form hemispherical heads. We can also see the effect of three hits which caused minor damage, perilously close to a gun port. We can also see that each gun port was formed by boring three overlapping holes. Eight layers of plate are visible in the nearest port, and beyond those is a collar bolted to the inside of the turrret. The photograph also shows how the wheelhouse was modified after the battle of Hampton Roads by the addition of sloping plates aimed at deflecting shot. We can also see how the deck and upper part of the hull are protected by riveted plates.

An award-winning accurate scale model of Monitor's engine was constructed by Rich Carlstedt, who undertook a considerable amount of research, including examination of the salvaged engine. See here for background information, here for photographs, and here for a forum discussion.

Part of Monitor's vulnerability to rough seas stems from water ingress at the turret's seating ring. It is said that the problem arose due to the insertion of a gasket of rope and other soft material, contrary to Ericsson's plan of having metal-to-metal contact. This sounds fine in principle, but it would be interesting to know to what extent adequately flat surfaces had been obtained on the seating faces of these 20 ft diameter components. Was there a problem, which led to the decision to insert a gasket?

Although Monitor was not badly damaged by Virginia's guns, the wheelhouse was hit and put Captain Worden out of the action. With the low, flat deck, and limited defensive capapbility, Monitor would have been very vulnerable to boarding, when the wheelhouse and turret might easily have been put out of action.

See Also

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