The Daily Telegraph. SATURDAY, APRIL 11, 1883.

Daily Telegraph (Napier), Issue 3666, 14 April 1883, Page 2

The Daily Telegraph. SATURDAY, APRIL 11, 1883.

One of the competing engineers for the Harbor Board's bonus for the best designs for a harbor for Napier ■is Mr C. D. Irvine, of AVcllington, from whom Aye have received a copy and accompanying plan of tho Avorks he proposes should bo undertaken. Tho general scheme of Mr Irvine's design may be best compared to that of MiMcGregor's, Avith Avhich most of our readers are acquainted. Starting from the end of the Shakespeare road it is proposed to run out a pier at right angles aa Ith the beach for half a mile, and from that point cui-A.-.i'r round to a lighthouse a total distance from the shore of 53-10 feet. From the AVestern Spit another pier is run out 2GOO feet: leaving an opening between the two pier heads of" 8-10 yards. The water thus enclosed, called the outer harbor, Avould be of an area of 3-13 acres. The inner harbor would be as it is uoav of -10 acres in extent, and proA*isions are made for jetties, quays, ko. ; and the dredging of the Iron Pot is a part of the scheme as avcll as of the present channel between the cr-sting east and Avest piers. In connection Avith the Avorks is a stone weir embankment, composed of rubble, constructed underneath the present Port Ahuriri bridge, -with fifty-one sluice channels, and tAvo canal locks. The estimated total cost of the Avork is £2-10,932. Mi-ll-vine says of his proposals that Sir J. Coodo and Mr Carruthers Avould no doubt suggest tho same objection to this design as that made to Mr McGregor's proposal to foim a close harbour between Napier Bluff and the existing entrance by saying "that the shniglc travelling along the coast between the Tuki Tuki and Napier Bluff avoulc! gather against the lack of the protecting pier, and evcntualy passing along the outer kant be deposited at the entrance." Should, however, my deductions on this point, AA*hich arc contrary to the foregoing, be incorrect, and should it eventually happen, after the lapse of some years, that shingle began to creep round the outer kant of the east pier at D, it is obvious that another long lease of immunity from trouble could be obtained by the construction of a narrow concrete groin or reef running- out from D in the direction slioavii and marked D N, which could again be further extended, and so on until tlio exact conditions of equilibrium or stoppage of shingle be obtained. But 1 submit that the burthen of the construction of a work of this kind, supposing it ever to be found necessary, might Avith safety be left to ji future generation. A perusal of Sir John Coode's report and accompanying plans of the date of Ist July, ISSO, shows that the design of the works hitherto carried out at a cost of some £80,000, and approved of by him as " based on sound principles" page 5, consists almost entirely of one Avork : the remOA'al of the bar by straightening the entrance to the lagoon and confining it Avithin two parallel Avails, forming a channel 100 feet wide and upwards of a quarter of a mile iv length, having an ebb and fioAv current i-i the channel of sonic seven miles an hoar. Now this method of removing a bar, although efficacious within certain i; .mits, is yet only temporal-}-, and requires subsequent, repeated, and successive extensions, ahvays becoming- more and more costly as the piers are carried out into the sea ; and besides it should not be forgotten that the longer the channel becomes the more objectionable and dangerous does it become to traffic. Sir John Coode also attaches considerable A*alue to the tidal scorning power for deepening the entrance to the lagoon, and yet he subsequently recommends in the case of Napier (see report, page 7) an expenditure of some £8000 for, "still further improving the channel by dredging to at least thirteen feet beloAV loav-water spring tides." AAHiy should the "scouring power," Avhich acts backwards and forwards nearly alike, be of such value if the dredge has finally to do thoAvork;-* And if the dredge has to be used at all, is it not best to use it Avhere it can be applied with tho greatest effect and least cost, as slioavii and marked at 0 and Q. Another objection that may perchance be raised against the design that I Ikia*c projected is to the effect that as the oast pier C I) I would trap all shingle noiihAvard, the beach immcd-'ately to the north of Port Napier Avould become denuded of its shingle, and consequently be left exposed to the action of the Avaves. See Appendix to the Journal of the House of Representatives, N.Z., Vol. I. ISBO ; Timaru Harbour AVorks Paper No. I. (Further report of the Colonial Marine Engineer as to the damage caused by building a brcakAvater at Timaru, and the further damage that may accrue therefrom), and the subsequent papers with enclosures, kc My answer to_ this objection is contained in the piintcd "Memoranda of the Port of Napier" forwarded to intending competitors, where under the heading "Travelling Shingle" it is stated that " the shingle from the Tuki Tuki is reduced almost to sand by the time it reaches AVhakaari," a distance only of about ten miles to the north of Napier. A design consisting of a brcakAvater more or less parallel to the shore with an opening between the shore end and the beach to permit the '' travelling shingle to pass through has been advanced as a method of getting over the shingle difficulty : but a little reflection A-.'ill show that a brcakAvater so constructed Avould cause still Avater on the beach under its lee, and this in turn -would, cause the shingle to stop in its oiiAVard course, so that the accumulation of shingle on the part of the beach sheltered by the breakwater would in time become a shingle bank advancing into and filling* up the sheltered portion of the Avater extending between t__\ beach and the breakwater, and cvcutiJjPN the harbour itself Avould be filled in}-.- - "-^j