[taken from pp185/6 of Sir John Rennie's The theory, formation, and construction of British and Foreign Harbours, illustrated by numerous examples (2 vols 1851-1854)]

Sir John Rennie on Douglas Harbour

DOUGLAS HARBOUR.

 

John Rennie - Douglas harbour
part of Plate LXXVII

DOUGLAS, the second, if indeed it be not the principal, town in the Isle of Man, is situated in latitude 54 12" north and longitude 4 27' 47" west, and on the east side of the island.

The Town is built, in the S. W. angle of a fine bay, of the same name, which is 2 miles wide and 7/8ths of a mile deep, and at the mouth of a small stream called the Douglas or Blackwater river, which discharges itself into the sea there. The banks of this river are lined with quays on both sides throughout the extent of the town, and the latter may be considered on the whole to be well built; its population is about 8000. In the summer many visitors resort to it for the purpose of sea - bathing, and the low prices of articles of domestic use render Douglas a favourite residence for people of limited incomes. Of late years the abolition of some local privileges has, however, modified this state of things.

Formerly the Duke of Athol, the independent king of the Isle of Man, had a large seat, about half a mile distant from the town, on the shores of the bay, known as Mona Castle. Since the year 1826 this has been converted into an hotel, for which purpose its dimensions, style of construction, and position, rendered it highly appropriate. About the same period the remaining feudal rights of that nobleman were purchased by the Crown, the sovereignty having been previously extinguished in 165, and the Customs' regulations, and civil laws, to a great extent, assimilated to those of the rest of the empire; by which means the smuggling formerly carried on to a great extent from the island was effectually suppressed.

The inhabitants are an offshoot of the Celtic race of Northern Ireland, known by the name of Manx. They speak a peculiar dialect of the Celtic language, and retain in their local legislation many of their ancient customs and regulations. The ecclesiastical affairs of the island are under the direction of the Bishop of Sodor and Man, but he has no seat in the upper house, nor does the island return a Member to the House of Commons.

The river Blackwater, which forms the Harbour of Douglas, rises in the ridge of hills passing through the centre of the island, at a distance of about 10 miles from the town, and falls into the sea at the bottom of a small subsiduary bay formed at the south-west extremity of the principal one by the projecting ledges of the Pollock Rocks and Douglas Head. The entrance is protected on the N. W. side by a well-built stone pier, carried out in a direction nearly E. s. E. to a distance of 650 feet, terminating with a circular head, upon which is erected a small light-house. The tide ebbs out to the end of the pier, so that the harbour is nearly dry at low water, excepting in the channel of the river. Spring-tides rise from 10 to 20 feet, equinoctial springs from 21 to 23 feet, and neap-tides from 10 to 14 feet, so that vessels of from 150 to 200 tons can always enter at high water. The bay is surrounded by steep hills of moderate elevation, consisting of the Cumbrian series of the palaeozoic formations, and presenting an irregular outline at high-water mark, with many abrupt projections and bays, producing counter- currents in various directions, the velocities and duration of which differ in almost every case. From the fact, also, that the bay of Douglas is situated nearly upon the line of meeting of the two branches of the great tidal stream passing respectively round the northern and southern extremities of Ireland, great interference with the regularity of the main currents may often be observed. Clear of the rocks there is good anchorage in a sandy bottom.

The bay is open from N. E. to S. S. E., or ten points of the compass: gales from the S. E. are the most dangerous, and drive in very heavy seas; unfortunately also they occur frequently, and occasion great loss of life and property. In the harbour itself the agitation produced by winds from that quarter is severely felt, and it had been increased some time since by the injudicious removal of a reef of rocks which served to break, to a certain extent, the force of the sea. A jetty was therefore erected, under my directions, upon the rocks below St. Ann's Fort, which has remedied the mischief so caused; but as the other works then proposed were not carried into execution, there is still a very considerable agitation in the harbour during the prevalence of some winds. I recommended the continuation of the pier to a further distance of 200 feet, with a corresponding jetty projecting into the channel so as to break any seas driven in, and to reduce the width of the entrance to 100 feet: the direction in which it was proposed to extend the pier was also designed to guide the currents, and to increase the scouring action of both the flood and the ebb tidal waters. At the period when these works were suggested, the formation of a large harbour of refuge in Douglas Bay occupied a prominent position in public opinion; the construction of any works which might eventually be rendered useless by the execution of the larger scheme was therefore suspended. The extension of the old pier was considered to be of that description, and the inconveniences attached to the harbour were for this reason only partially remedied.

There can be no doubt with respect to the necessity for the formation of some asylum harbour in the main track of the immense trade carried on between the numerous ports of England, Scotland, and Ireland, towards the northern extremity of the Irish Channel. The central position of the Isle of Man, and of the bay of Douglas in the latter, forms an excellent position for the asylum so much wanted. For many years public opinion appears to have been nearly unanimous upon this subject, to which Sir W. Hillary contributed greatly by his writings; and even so far back as the year 1835 I was instructed by the Board of Public Commissioners of Harbours to report to them as to the practicability of the execution of such a work, and to inform them of the probable expense of a harbour of refuge capable of receiving the vessels which might be compelled to resort to it at all times of tide, and to allow of their departure whenever it might be judged advisable to put to sea. In consequence of these instructions I presented a Report, of which the most important points are comprised in the following paragraphs, accompanied by a general Plan represented upon Plate LXXVII.

The principles which guided me in the preparation of the Report and Plan were: firstly, to secure protection against the most dangerous winds; secondly, to secure perfectly free ingress and egress at all times of the tides : thirdly, to maintain the natural circulation of the currents in order to prevent any deposit which might silt up the harbour; fourthly, to provide ample space for the reception of the greatest number` of vessels likely to resort to it. These are, it may be observed, the abstract principles which ought to regulate every work of a similar nature; and the works designed in accordance with them for the harbour of Douglas were proposed to consist of-

Firstly, A breakwater pier connected with the mainland at Douglas Head, and carried out to a distance of 340 feet. Secondly, A detached breakwater, 1400 feet in length, consisting of three arms, with a general direction nearly north and south, but bearing a little towards St. Mary's Rock. Entrances of from 100 to 150 yards were proposed at both ends, with a depth of 7 fathoms at low water of spring-tides; and

Thirdly, A breakwater pier, 400 feet long, carried out from St. Mary's Rock to meet the detached breakwater.

The estimate for these works amounted to £225,000, and they would have effectually sheltered from 100 to 150 sail of the largest class of vessels frequenting this coast. The enclosed area would have been about 45 acres of water, presenting a minimum depth of from 9 to 30 feet at low water of springs. Notwithstanding, however, the unquestionable advantages which the execution of this plan would have produced, it was found to be impossible to obtain the consent of those interested in the navigation of these seas to a passing toll; and as the resources of the island were inadequate for the purpose, its execution has been deferred. I also made designs for other situations on the island, such as Castleton, Derby Haven, Peel, and Ramsay, for the attainment of the desired object; but Douglas Bay appears to possess local advantages which ought not to be lost sight of, should the means of constructing a harbour of refuge on the island ever be obtained.

The jetties and breakwater were proposed to be formed of rubble masonry pierre perdue.

 


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