Sailing rigs were fairly common on steamships throughout the 19th Century. This was because of the flaws of steam machinery at the time. Especially in the early days of steam, it was highly inefficient. Steam engines consumed coal at a high rate. In 1865, the Royal Navy ran a race between three of its frigates to test the 'compound engines' (engines which used two or more stages of steam expansion) that were now becoming available. Two of the ships, Arethusa and Octavia had 'simple engines', while the third, Constance, had a compound engine. The ships raced under steam from Plymouth to Madeira, a distance of about 1,200 nautical miles. None of the three would reach it under steam. Constance, operating with the most efficient engine, would run out of coal 30 NM short of the island, having burnt two tons of coal an hour over the 124 hours she had been steaming. The other two ships made little over 1,000 nautical miles under steam. The inefficiency of the engines combined poorly with the difficult logistical challenges posed by steam. With these high rates of coal consumption, most ships could not carry enough coal for long voyages with steam alone.

This could be compensated for by stopping at coaling stations to refuel. However, maintaining coaling stations was a tricky task in its own right. Coal was rarely mined where ships needed to stop off to refuel. This meant that it had to be carried to where it was needed by colliers. Given the hunger for coal, this meant large fleets of colliers. In 1870, the P&O Line, which ran steamships from the UK to India, needed a fleet 170 sailing colliers to support its steamers. The challenges grew larger as you got further from the best coal mines. The Pacific, in particular, had few coaling stations, due to its vast size and the distance from the coal mines of the UK. Welsh coal was viewed as the best available, due to its high energy content, but it cost nearly 1.5 times as much in Singapore as it did in Gibraltar. These difficulties meant that most ships meant for long-distance travel had sails, as well as their steam engine.

Sails would be meant for long voyages, while the steam engines would be used when the wind was low, or would be against a sailing ship (as well as for tactical use in the case of a naval vessel). They would not be used together, due to the risk of fire. Ships with both could travel fairly well under either method of propulsion. However, they were not as fast as ships that used only one. Masts and rigging imposed significant drag, and could slow down a steaming ship by up to 1.5 knots. Meanwhile, a sailing ship would experience drag from the fixed propellers of a steam engine. While ships could have movable propellers, which could be hoisted up into the ship when not in use, the aperture this left made steering harder.

Huascar was not a monitor, she was a 'turret ship'. The difference between the two is small, but significant. Monitors had a turret on a raft-like hull with little freeboard (the distance between the top of the hull and the waterline). Turret ships, meanwhile, mounted their turret on a ship hull with higher freeboard. This made them true ocean-going craft, unlike monitors. Huascar, like other turret ships, had sufficient freeboard to operate in open water without the need for special precautions. This was also made possible by design choices, such as her high forecastle with a sharp break to the well deck where the turret is positioned. This gave her a very high freeboard forwards, while keeping the heavy turret low in the ship to increase stability. As such, Huascar crossed the Atlantic under her own power, including some time spent off Spain hunting for merchant ships. Turret ships were more stable and seaworthy than monitors, but still had their problems; the high weight of the turret meant they were less stable than other ironclads. This fact was dramatically exposed by the loss of HMS Captain to a storm in 1870.

True monitors, with their very low freeboard, had trouble crossing oceans. In 1866, the US Navy sent two of its monitors on long ocean voyages. Miantonomoh crossed the Atlantic, while Monadnock was sent to San Francisco via the Straits of Magellan. With a freeboard of 2ft 7in, they required significant preparation for the voyages. The hatchways and other openings were given additional protection, in the form of a 2ft high coaming (a bulwark surrounding the opening). The hatches were also kept closed at sea, wherever possible. The monitors were also accompanied by other ships, which could be used to tow them. Miantonomoh was assisted by the paddle steamer Augusta, which towed her for 1,100 miles of the journey.

As far as books go, my first recommendation would be D K Brown's Warrior to Dreadnought: Warship Design and Development 1860-1905. Focused mainly on British warship design, it provides a wide-ranging introduction to the warships of the period, and the thinking and technology that went into them. Norman Friedman's British Cruisers of the Victorian Era and British Battleships of the Victorian Era go into greater depth on the same topics as Brown's book. Greene and Massagnani's Ironclads at War is a fairly comprehensive overview of naval warfare in the ironclad era, from the early experiments in the Crimean War to their use in colonial wars by Britain and France in the early 1880s. While it could be more detailed, it's one of the few works that covers the full spectrum of ironclad use.

I can answer most of the second question . The designer of the Monitor, John Ericsson, created a very special-purpose boat, primarily designed to being hard to destroy with cannon fire. To that end, he designed a hull with almost no freeboard , i.e. it didn't stick up out of the water very much. He also gave it a very heavy turret, that could take a beating and still rotate, and shallow draft. Those three things were excellent for something acting as a sort of mobile fort, for guarding a harbor. They were however very bad for an ocean-going vessel. Rough water and high waves that could be encountered out at sea could easily slosh over the deck and get in through ports, under the turret, and into other openings. The great weight of the turret sitting on a shallow-draft hull, made the center of gravity of the boat very high, and that made it more likely to roll, and easier to flip- generally speaking, it is a bad thing to weight a boat so that it wants to float upside down.

The crew of the USS Monitor seemed to have anticipated problems when it was decided, at the end of 1862, to tow the ship down to Cape Hatteras. The North Atlantic in winter is usually bad, and that part of the coast of North Carolina famous as a ship graveyard. They tried very hard to plug gaps and seal ports. But when they encountered rough water and high winds, the flexing of the iron hull opened up joints and dislodged plugs and packing. Worse, their pumps were, as could be expected, steam powered, and as the water rose in the bilge, the boilers began to fail to provide steam. They were under tow from the steamship Rhode Island, and there seem to have also been problems with quick communications. When it was decided to abandon the boat, it was impossible for the tow ship to get her boats back and forth fast enough to save all the crew, and a number were lost. More monitors would be built and used during the Civil War, but they saw service away from the ocean- notably, on the Mississippi. They also had more freeboard than the original, relying more on angled-armor than putting everything below the waterline.

I am not very familiar with the Huáscar , but it clearly had more freeboard than the Monitor, and greater draft, which would have made it more stable.

The USS Monitor was located and reclaimed. The Mariners Museum of Newport News VA has undertaken the conservation of it, and has a very fine exhibit. You can read their article on the final voyage here.

James Nelson's Reign of Iron is a readable history of the USS Monitor and, of course, the Virginia .