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• 1807, Robert Fulton's Clermont the first ship to demonstrate the feasibility of steam propulsion for commercial use, but it also carried sail.




• 1819, The first steamship to cross the Atlantic was the American City of Savannah, but it also carried sail.




• 1837, Britain's steam-powered Great Western established regular transatlantic passenger service, but it also carried sail.




• 1838, SS Archimedes was the first steamship to be driven by a screw propeller, but it also carried sail.




• 1871, The first British Navy ship not to carry masts or expensive sails the H.M.S. Devastation..




• Commercial steam ships regularly carried masts and auxiliary sails into the 20th century (1900s).

Question:

IF steam power was superior to sail, Why did it take so long to abandon sail after steamships were demonstrated?.

I think it comes down to a few basic factors:

1. Early steam engines weren't very efficient or reliable. So it made sense to retain sails as a backup should the steam engine(s) breakdown or should the ship run out of fuel (especially on longer oceanic voyages were replenishment was uncertain).




2. Wind-power is essentially free (once you've invested in the masts & sails in the first place), whereas you had to keep buying coal. As the steam engines were inefficient it made sense to have sails to supplement steam. This could be in the form of using them both together to add a few knots to the ship's speed or using one or the other as circumstances demanded (i.e. steam into the wind, sail down wind).




3. Sailors are a superstitious and conservative folk, they knew sails and sailing, and it took some time to wean them off.




4. The transition was dependent on a number of later technological changes, such as improvements in boiler design (to improve power, reliability and efficiency), the introduction of iron hulls and the introduction of the screw propeller, to make steam power capable of replacing sail.

Steam was introduced into naval service when it could improve an existing system, or provide a new method of carrying out essential business. It did not revolutionise the conduct of operations at sea overnight. Early steam engines were expensive, heavy, uneconomic and ill balanced. They were far from ideal power plants for wooden ships.

...

The 1840s witnessed a number of vital technological developments, of which the screw and the iron ship were the most obvious. Equally important breakthroughs in iron production, boiler design, bearings, lubricants, manufacturing and control systems were essential to the development of modern warships. Many of these technologies were drawn from other engineering sectors. By 1850 steam ships were effective and reliable enough to be used globally, while fuel supplies. engineering back-up and vital docking accommodation were spreading to meet the need. Although a few key commercial routes already carried steam shipping, this was a luxury market, catering for passengers and mail, not bulk produce.

…

[For a warship] it made sense to fit a square rig so the ship could cruise under sail, saving the coal for tactical demands, and emergencies.

^{The Sail and Steam Navy List, R. Winfield (2004), pg.17}

You can't completely replace sail with coal until you are 100% sure that you are going to have access to coal everywhere you need to go.

This is basically an extension of Steve Bird's #2. It's beyond the economics and into the availability.

Do you have reliably supplied coaling stations all the way to, say, Australia? If not you need to keep sails on hand.

As an example the famous Clipper Ship Cutty Sark was one of the fastest trading ships in the world when she launched (1869) and was used for the China tea trade. But coal quickly covered that route so then she was diverted to trade with Australia.

1- Reliability. The first steam engines were prone to breakdown. That's not good in a mine or in a factory but outright dangerous on a ship. It took time before engines were reliable enough for ocean journeys.

2- Sufficient range. You can't bunker coal in the middle of the Atlantic. Ships need sufficient bunker capacity and still be able to operate economically. In other words, ships had to be large enough to carry both coal, cargo and still make a profit.

3- Infrastructure. One harbor on each end of the Atlantic with enough bunker capacity is not enough. You need coaling stations everywhere.

Developing all of the above took time.