THE PORT OF OTAGO

Evening Star, Issue 15344, 19 November 1913, Page 5

THE PORT OF OTAGO

HOW IT HAS BEEN IMPROVED. NOT NOAV A BAR HARBOR. Mr J Bliir Mason, engineer of the Otago Harbor Board, lectured last night, heforo the Technological Branch of the Otago Institute, his subject being one on which he is tho leadingauthority— namely, 'The Improvement Works in Otago Harbor.' Mr Mason has known tho harbor since bis boyhood. As a young man he took tho soundings and mado the borings that served .is the data for Sir John Coode's report; and to-dnv he could from memory draw a. detail map of the whole area from tho Heads to tho Dunedin wharves. Hit, lecture was illustrated with many lanterned charts and plans, and it constitutes a comprehensive record of the works from tho start. Mr E. E, Stark presided. Over 30 members listened attentively to the lecture, and expressed their sincere thanks to Mr Mason. The lecturer began with tho survey made by Captain Stokes, of the Acheron, in 1849, and referred to Mr D. L. Simpson's survey in 1879, when the depth on the bar varied from 15ft to 17ft at lowwater. In 1882 it war, noted by Captain 'Jhomson, harbor master, that the inner shoal between Harrington Point and Black Head had disappeared. In those days, under favorable circumstances, such ae a smooth sea and good tides, vessels of 21ft draught could cross the bar and proceed to the anchorage at Port Chalmers. Vessels drawing lift could navigate tho Upper Harbor and anchor off Grant's Braes. Small vessels of 6ft draught could proceed to Dunedin and lie alongside tho primitive jetties and landings of the early settlers. Tho reports on harbor improvement by Messrs J. M. Balfour, G. M. Ban-, W. N. Blair, John M'Gregor, and J. T. Thomson dealt principally with tho Upper Harbor, tho depth, of water in tho Lower Harbor being considered sufficient for tho class of shipping of that period. Mr Balfour's proposal was to build a, great training wall from Portobollo to Dunedin, tho object being to place Dunedin at the centre of a channel 12 miles long, instead of at the upper end of one s;x miles lon,' from Quarantine Island. The effect of these works would bo to virtually increase the length of the harbor by about s-even mile:, mak'ng the bead or clack water end of the harbor at Portobello. Tho cost of this scheme was estimated at £9-1.550.

Mr John M'Gregor proposed to dredge .", channel in about the fnnw position as that of tho Victoria, channel, with low walls on each side, and construct a curved wall along tho foreshore to Dunedin, as tho boundary of reclamation at Dunedin, in about the same position as that proposed by Mr Balfour; Mr M'Gregor estimated th'.> cost of dredging tho channel, building retaining walls, anil the purchase of ;wo"<Lvodges at £125.000. Tho cost, of construction of deep-water wharves at Punediii, 3.000 ft long, was estimated at £60.000, bringing the"total to £185,000. Mr .L X. Blair generally approved of Mr Balfour's idene, but considered that he had underestimated the difficulties in marking out his scheme, and also the cost, of the same.

Mr Ban- also considered that Mr Balfour's scheme could not be depended upon to deepen the channel to the extent anticipated by that, gentleman, and that extensive dredging would be necessary. Ho estimate the total tost of the walling at £73.127 and iho cost of dioddng ° at £BB.IIO, .making a total estimated expenditure of £161,257. Mi- W. N. Blair considered the principle of Mr BaKour's scheme as the correct one, but thought it impossible to construct tho wall of the section proposed by Mr Balfour, which was only 2ft wxle at the top, consequently could not carry a temporary railway on it, which was 'considered by Mr Blair the meet economical way of forming the wall. He estimated the total cost of the central training wall at £120.000. against Mr Balfour's estimate of £15.000.

Messrs M'Oregor, Bnrr, and Blair did not put forward any schemes of their own, but simply stated their opinions with respect to Mr Balfour's scheme. Mr J. T. Thomson strongly oppesod any interference with the existing tidal currents, and thought that no obstruction should be placed against the influx and lcfhoc of the tide. H : ,s .advice was to retain the then exist ins channel extending along the east side of the harbor for the use of the coasting trade, and with which the improvement of the channel along the west side of the bay would in no way interfere.

The board's first engineer. Mr D. L. Simpson, I'nHy recognised the importance of improving the waterway to Thmedin. In 1575 he completed a survey of the hav.bor, and his observations made while undertaking that survey led him to recommend the cutting of the north channel, now known as "Victoria, rbannel. as the future deep-water channel to Dunedin. After the work was commenced, the board decided first of all to dredge a channel to a minimum depth of 12tt at low water, with a width of 70ft. so that access might be given to vessels up to 17ft draught. This was estimated to involve an expenditure of £135,927. The deepening of the channel to a depth of 21ft, with a width of 300 ft, was considered to be the ultimate objective, dredging to such end to be. done out of revenue, as funds permitted from year to year, and as tho trade of the port demanded. This policy has been pursued by the. board up to tho present time. The mean depth of the 'Victoria- channel throughout is to-day-over 22ft at low water, with a minimum depth ot 19ft. which can with a, few months' work be increr.sed to 21ft. The objective of the board at present is to attain a depth of 22ft at low water, so as to allow of ths passage at high water of vessels of 25ft and 26ft draught, This requires, of course, a low-water depth of 26ft or 27ft at the Dunedin wharves and basin, so that vessels may remain afloat at all states of the tide. Owing to the press of news we must break the lecture at this point. In a subsequent issue we shall give, an outline of the rest of Mr Mason's valuable remarks. 'Meanwhile ve append this impressive statement: With the opening of the new channel at the entrance in 1896 the port of Otago ceased to be a bar harbor, and it is to-day as easy of access for the largest vessels as any port in the Dominion.