A slipway is a ramp on the shore by which ships and other vessels can be moved to and from the water. They are used for repairing and sometimes building ships and boats. As the word "slip" implies, the ships or large boats slide over the ramp. Prior to the move the vessel's keel is coated with grease, which then allows the ship or boat to "slip" off the ramp and progress safely into the water. Slipways are used to launch (newly built) large ships, but can only dry-dock or repair smaller ships. Pulling large ships against the greased ramp would require too much force. Therefore, for dry-docking large ships, one must use carriages supported by wheels or by roller-pallets. These types of dry-docking installations are called "marine railways". Nevertheless the words "slip" and "slipway" are also used for all dry-docking installations that use a ramp.
Maintaining and repairing the hull of a ship
The traditional method to gain access to the lower hull of a ship is called careening. In its most primitive form, this was done by beaching a ship, putting it dry at low tide. It is assumed that the ancient Egyptians already practised this. One of the many problems related to careening was that it was primarily suitable for maintaining and small repairs. Major repairs were difficult and some repairs simply could not be done while the ship was on its side. In 1806, a Dutch newspaper noted that multiple Dutch ships of the line had been broken up, because some minor defects to the keels could not be solved by careening. By taking its first Dry Dock into use, the Dutch Navy solved this problem.
Early slipways The first artificial means for beaching were found at Carthage. Here, war galleys were drawn up a sloping shore on timber ways or slips. This was probably also done because the tidal range in the Mediterranean Sea is very small. Whatever the exact reason, it would have allowed the Carthaginians to effect all kinds of repairs. For small vessels several practices were used. In early 19th century Britain, it was not uncommon to use capstans to pull vessels of up to and slightly over 200 tons up on the beach. Another practice involved towing a vessel up on rollers. These did not have an axle and therefore had to be placed in front of the vessel and then be replaced as the vessel moved up. The word 'slipway' can be found in the English language from at least the mid-1830s. Appearing as two words, it was used to refer to two patent slips (see below) in 1834. In an 1832 instance it was used to refer to the 'ways' of a building slip that was used to drag a ship up on a slip in the traditional way, i.e. before the patent slip was invented.
In 1832, George Graham, a shipbuilder from Harwich described the traditional way of hauling a ship up on a slip. It involved capstans, laying ways, and use of a temporary cradle without wheels or rollers. It was a costly operation with high risk of damaging a vessel. Most of the cost was caused by that a ship had to be prepared in every way like a ship that was to be launched. Mr. Graham dragged up ships of up to 1,000 tons. In 1817, the Royal Navy had gone further and had hauled up the ship of the line Kent of over 1,800 ton on to a 'regular' building slip. Therefore, it seemed that by 1817, every ship could be hauled up on a regular building slip. If one considers the details of how Kent was hauled up, it becomes clear that many costly changes were made to the building slip in order to haul up Kent. This implies that already before the invention of the patent slip, there was a distinction between slips (i.e. building slips) and slipways (slips used to repair ships). In theory, both could be used for building and repairing, but it was more economical to configure a 'slip' for one primary purpose.
Early slipways in the Netherlands The Dutch equivalent for slipway is sleephelling, in German this is schlepphelling. In the Netherlands, the distinction between slips meant for shipbuilding and slipways was therefore much clearer. In a 1699 announcement, the sale of a shipyard in The Hague was announced. It had two careening places and a 'sleephelling to tow up ships'. Many of these early Dutch slipways only catered to small vessels. However, some slipways were bigger. In 1796, the shipyard of the Admiralty of Rotterdam had three slips (hellingen) suitable to build ships of the line. It also had a single slipway (sleephelling). This was also suitable to build a frigate of 24 guns. This shows that this slipway was not able to haul up a ship of the line.
Modern slipways
The patent slip
In 1817, the total cost of dragging up Kent was £1,436. The cost of bringing a first rate into a dry dock was only £35. However, building a dry dock cost about twenty times as much as constructing a regular (building) slip. No wonder that people sought for cheaper ways to put a ship dry for large repairs. In 1819, Thomas Morton of Leith, Scotland introduced the first modern slipway. As it was an invention, he applied for a patent in the United Kingdom and its dependencies and obtained it. The patent led to the name patent slip. In a very extensive 1832 parliamentary discussion about a possible renewal (prolongation) of the patent, it was never called a 'slipway'. It was named 'patent slip', or simply 'slip'. About fifty years later, the patent slip was seen as the first slipway. In many respects, the way that a patent slip got a vessel out of the water resembled the traditional method used on a building slip. Therefore, some people dared to say it was only an adaption of other inventions. After its inquiry, the House of Commons — which decided on these matters — clearly established that it was an invention. A patent slip could be built upon an existing slip. It required relatively heavy piling directly below the keel of a vessel and somewhat lighter piling where its sides would be supported. If there was little or no tide, the slip had to be extended below the water level. Upon the slip itself, three lines of 'ways' were fixed. These ways carried three cast iron rails that formed a railway.
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