HARBOR WORKS

Evening Star, Issue 17696, 24 June 1921, Page 3

HARBOR WORKS

COMPARISON WITH THE CLYDE,

Tho following letter has boon addressed to tho secretary of tho Otago Harbor Board by Mr Edward Roberts, M.l.Mcch.E.; ' Dear Sir, -Although no longer a member of tho board, I continue to take an interest 1 in the board’s works, and, having gathered some information which may perhaps be of sorvico to tho members in coming to n. decision on an important matter now before them I have pleasure in placing the same before the board. In the newspaper reports ol the. last meeting the engineer_ stated that there was now a channel of a minimum width of 300 ft, with a minimum low water depth of 30ft from the Hoads to Port Chalmers The heard had fixed the width of the Deborah Bay cut at 500 ft, but he advised that the widening to this width be postponed until the Mussel Bay reclamation was undertaken. The information 1 place before tho board relates to the widths and depth of the channel of the Clyde in the year 1015. It is taken from the ‘Transactions of the Institution of Civil Engineers,’ volumcCC., in a paper by Sir Thomas Mason, engineer to the Civile Trust:—The deep water channel of the" Clyde is 350 ft wide from the Clyde Trustees' boundary, eighteen miles below Glasgow, for seven miles upwards; thence it diminishes to 300 ft at Krskine berry, nine mixes below Glasgow, and to o2Dit at tho River Carl, six miles'below Glasgow. Above this the. width is mneb reduced, being 200 ft at. Renfrew'and j00;t at the entrance of Glasgow Harbor. The widths are increased at curves except in those of large radius. There are nine curves of radius between three-quarters of a mile and one mile, and on short, curve of 3.20,)ft radius. I.inei.s of 500 ft and 600 ft. with draught of 28ft to 29ft, go right up i" llte entrance ot Glasgow Harbor Princes Dock. The depth of this channel is 24ft at low water and 10ft rise at spring titles. Tho channel of Otago Lower Harbor compares most favorably with the. Clyde. Ibo channel in 1919 tvide engineers repott), commencing from the molo end with a width of 500 ft and 38ft depth, reduced from pile No. 1 to black beacon to 350 ft. with a depth of 34'.ft. and from No. 5 beacon nearly to Xo. 9 beacon, about two and a-quarier miles, the widths are 500 ft to 700 ft. with depths of 35ft to 40ft: tlicnco Ike channel opened out to 1.200 ft wide at the quarantine ground, with not less than oOft depth ami 24ft at sides. The next portion is the Deborah Bnj curve, which has boon now dredged to 30ft for a width of 300 ft as a minimum, but is much wider in the greater portion. All the curves arc very easy, that of least radius being Deborah Bay, which is .‘f,oooit, as shown on the latest plan. The rise of’tide at springs is 6ft Gin. The above comparison shows that from ihe end of the molo inwards to Port Chalmers wc now have a channel wider than that of the Clyde, and with a depth of 36ft 6in at high water spring tides, compared with that of the Clyde in 1915 of 34ft at high water springs. Surely this should be sufficient for the present, especially m view of the fact that only one vessel has left loaded to 29ft 6in during the past twelve inon ths, while the Clyde channel has been sufficient tor some of the biggest ships in the world, notably the Aquitania and Lusitania, which were built on its banks. teeing that we have a good channel to Port Chalmers, fit for any vessel likely to visit the Dominion, would it not be well to take the engineer's advice, and at the same time stop the expensive policy of bringing one load per day from beyond Port Chalmers to fill up Lake Logan, when two loads per day can be obtained close at hand, and at the same time tho pump dredge kept fully employed, while tho consequent deepening' of the Victoria Channel would be of tho greatest benefit, enabling ships which now have to wait for high water to come up to town at any stale of the tide?