Photo. Frank & Sons, South Shields.
The “Drottning Victoria.”
Ferry-boats of other types exist by the score, from barges upwards, propelled by an extraordinary assortment of contrivances, some of the older and quainter of which have been referred to in an earlier portion of this book. The historic Tyne ferries were withdrawn not long since for financial reasons, but an attempt is being made to restart them. The ferries at Glasgow and over the Mersey have each their own special features, and even the Thames has not always been without penny steamers. The Thames Steamboat Company and other organisations have made the experiment. The later effort of the London County Council to establish a service deserved a better fate, for the boats were well built and the engines were compact and powerful for their size.
The necessity of keeping open waterways which Nature wishes to close annually by freezing over, led to the invention of a species of vessel planned with that object. The most famous ice-breaker is the Ermack, launched in 1899 by Messrs. Armstrong, Whitworth and Co. for the Russian Government, for which she was designed by Vice-Admiral Makaroff. Many of the harbours of northern Europe are frozen over for the greater part, and sometimes the whole, of the winter, to such an extent that the ice attains a thickness of several feet; and navigation is at a standstill so far as those ports are concerned. The only way of keeping a channel open is to prevent the ice from freezing too thickly to permit of the passage of vessels, and this is done by keeping a vessel moving frequently up and down the channel to break the ice before it can freeze so thickly as to become impassable.
An ice-breaking ship, to perform its allotted task, must be both weighty and powerful, and capable of travelling at a speed sufficient to give her the required momentum so that she may break the ice by the sheer force of the blow she delivers when she rams it, and she must be strong enough to inflict and not sustain damage by the collision. Further, besides cracking the ice into fragments weighing a few score tons apiece, she must be able to slide upon the ice and crush it by sheer weight. The Ermack is 305 feet long, 71 feet beam, and 42 feet 6 inches deep. She had three screws aft and, when first built, had a fourth screw forward, the forefoot being considerably cut away to allow it to operate between the stem and keel. The idea was that the forward screw would agitate the water under the ice about to be struck and thus lessen the support the ice received from the water, and that it would also prevent an accumulation of ice under the ship’s bottom by creating a current of water towards the stern where the after propellers would throw the ice astern of the ship. This screw was found to be less useful than was expected, or rather it was discovered in practice that as good results could be obtained without it as with it in dealing with the massive Arctic ice, or any ice over a certain thickness, and when the ship was sent back to her builders a few years later to be lengthened, the forward propeller was taken out and not replaced. When the alterations were made the bow was severed in dry dock, and another bow having been built it was launched and floated into the dock and attached to the vessel. This bow is of a different shape from the other and has proved to be even more effective than the old one. Three screws aft are necessary in an ice-breaker of this size in order to give the power for the proper performance of her duties and also to enable her to be steered in very limited areas, greater steering facilities being obtainable by this means than by any other. The Ermack is fitted with three sets of triple-expansion machinery, having cylinders 25 inches, 39 inches, and 64 inches diameter, with a 42-inch stroke of piston, working at a pressure of 160 lb. The boilers are six in number, 15 feet in diameter by 20 feet long, working under forced draught. The machinery develops about 10,000 horse-power.
One of the Ermack’s feats was to rescue the coast defence armour-clad General Admiral Apraxine, which had got frozen in after stranding in the Baltic.
She finds no insuperable difficulty in smashing her way through ice 12 or 13 feet in thickness. The first piece of ice she ever attacked was drift ice about five feet thick, through which she went easily with her engines giving her little more than half-speed. The most serious test was against ice estimated at 25 feet thick, consisting of 5 feet of field ice, 9 feet of pack ice above it, and ice 11 feet thick, and perhaps more, below the field ice. Thick snow on top of thick field ice forms the most serious obstacle, the snow forming an immense cushion or ridge which becomes worse the more an effort is made to get through it. On another occasion she made her way by ramming through ice 34 feet in thickness. Another experience was to rescue eight of nine steamers which were nipped in the ice; the ninth was so badly squeezed by the ice that she sank before the Ermack could force her way to her.
A smaller ice-breaker, the Sampo, built by the same firm for Finland, has gone through sheet ice 12 inches thick at a speed of 8¹⁄₂ knots, and frequently through drift ice 10 or 12 feet thick.
On the other side of the Atlantic, whenever a severe winter is experienced, many of the Canadian and United States lake and coast ports are only kept open by means of ice-breaking ferry-steamers. Of the latter type is the Scotia, built by Armstrong, Whitworth and Co. for the carriage of railway trains across the Straits of Canso to and from Port Mulgrave, Nova Scotia. She is 282 feet in length, and on the rails laid on her decks she is capable of taking a load of nine Pullman cars, and can also accommodate an express locomotive and tender weighing as much as 118 tons. She has an ice-breaking propeller and a rudder at each end, and has two sets of triple-expansion engines of 1200 horse-power each. Her speed is rather over twelve knots.