The Patent Slip at Balloch, with the steamer THE QUEEN hauled up. (Photo Stuart Cameron)

The Patent Slip

One of Clydesite's most prolific and learned contributors is one Stuart Cameron. The breadth of Stuart's knowledge of shipbuilding and engineering is astonishing and we are very fortunate to count him as one of our band.

(Incidentally, Stuart is also a co-founder, indeed the very progenitor of the Clydebuilt Database, being the man who put together the some 21000 entries before approaching me years ago with the idea that it should be made available online)

He wrote this interesting history of the Patent Slip last year on Clydesite and I think it will be enlightening for those who are interested in the subject.  It is timely to publish this now, as one of the last remaining Patent Slips is being demolished at Renfrew to make way for housing and a marina. At one time the Clyde was peppered with these slips, now only Ardmaliesh Boatyard on Bute has one operating.  However, the Loch Lomond Steamboat Company recently were granted money from the Heritage Lottery Fund to repair the slip at Balloch, which has, it is believed, the only steam powered Patent Slip in Europe.

Now follows Stuart Cameron's post made on Clydeshipping on the 23rd March 2003.

WAVERLEY on Lamonts (now demolished) Patent Slip(Photo Stuart Cameron)

The Patent Slip

A few days ago, referring to the impending demise of the two patent slips at the former Clyde Navigation Trust ship repair yard at Renfrew, I indicated that the Patent Slip was an invention of the great Clyde iron and steel maker, engineer and shipbuilder Robert Napier. While Napier was an acknowledged engineering genius, responsible for the growth of the Clyde to a shipbuilding centre of world prominence, further investigation indicates that it may be an error to appoint the invention of the Patent Slip to him. The information that he was responsible for the ship repair facility of this type came from the writings of Michael S Moss, who singularly and with Dr John Hume, have produced many authoritative texts on Industrial Clydeside. I have not been able to check the source of Mr Moss’ statement on the Patent Slip but further information suggests that the true inventor of the Patent Slip was one Thomas Morton. Certainly a patent was issued in 1818 for ‘Morton’s Slip’.

In 1832, a House of Commons Select Committee under the chairmanship of the, Rt. Hon Sir George Cockburn, was convened to adjudicate on a petition by Thomas Morton to extend the duration of his patent. It seems that, as always, shipbuilding firms had been reluctant to be first into the arena in buying the new and unproven device and told Morton to come back when he could give references for an established an proven ship repair slip. As a result it was several years after patenting the device that Morton started to derive pecuniary recompense for his initial outlay of funds in the invention of the device. He sought to extend the patent (which had expired in 1832) in order to increase his recompense.

The Select Committee report provides some interesting facts on the early history of the patent slip as follows

- it was stated that the use of the patent slip in comparison with other means of ship repair (dry docking) had an established popularity by 1832. The comparative costs for the time were stated as £170 for dry docking compared to £3 for hauling out on a slip.

- Morton’s profit in the term of his patent (14 years) was adjudged to be a modest £5737

- The first patent slip was built at Morton own expense at Burrowstonness (Bo’ness)

- Within the first 6 years three other Patent Slips were laid down – at Whitehaven (Cumbria), Irvine and Dumbarton
.
- By 1832, a total of 44 Patent slips had been constructed in Aberdeen, Arbroath, Ayr, Berwick, Bo’ness, Carnarvon, Cork (2), Dublin (2), Dumbarton (2), Dysart, Edinburgh Union Canal, Glasgow (2), Goole, Harwich, Hull (2), Ipswich (2), Irvine, Jarrow, Leith (2), Liverpool, Londonderry, Lowestoff, Maryport, Montrose, Newcastle (2), Portsmouth, Quebec, Shields, Shoreham, Sunderland, Swansea, Sydney, Waterford, Whitehaven and Workington (2). In addition Morton had sent slips to Philadelphia, Russia and France for construction by others.

- At 1832 the largest slip could accommodate vessels of 800 tons but Morton was confident that they could be scaled-up to take ‘ships of war’.

- In 1832 a slip for vessels of 100 tons cost £450 to build rising to £1900 for a slip to take vessels up to 800 tons. The cost of a slip was one-tenth that of a dry dock.

- Morton acknowledged that ships had been hauled up previous to his invention but contended that his machines offered greater facility and safety. He indicated that a slip offered better working conditions with more and longer light.

- Ships could be hauled out at the rate of two and a half feet per minute by 6 men to every 100 tons – in the days before engine hauled slips

- The ship rested on its keel on a cradle rather than the bilges as in previous haul outs. The cradle was hauled up rather than the vessel.

- A Capt Basil Hall RN gave evidence of a similar device in New York in which ship’s were hauled out using the power of steam engines

- A Robert Wallace, giving evidence to the Committee stated that he was aware that the County of Renfrew and the Magistrate of Greenock would lodge objections to the extension of Morton’s patent. This may be partly due to Morton having granted exclusive rights to the Greenock shipbuilder Carsewell and had refused a licence to other Greenock shipbuilders McMillan and Duncan for laying down patent slips at their shipyard.

- The committee was also petitioned against renewal by a Capt Brown who had invented an ‘improvement’ on Morton’s invention based on the use of spherical rollers for the cradle rather than wheels on axles, It was said to greatly reduce the force required to raise the vessel from the water and eliminate axle failure which was stated to be a feature of Morton’s design.

Ultimately the Select Committee decided not to support Moton’s petition on the grounds of precedence but were sympathetic to his argument and expressed the wish that some other means of obtaining an adequate return for Morton could be found. It is not clear if this happened.

The full proceedings extend to some 36 pages.

The Patent Slip at Renfrew, with one of the last vessels to have been hauled up there, the LOCHNELL, TAKEN IN 2004 (Photo Stuart Cameron)