LYTTELTON'S NEW DREDGE.

Press, Volume LXVIII, Issue 14306, 18 March 1912, Page 4

LYTTELTON'S NEW DREDGE.

AttttlVAT. OF THE CANTERBURY. A NOVEL VESSEL. Tarnished and travel-stained after her long voyage of M.OOO miles from 'Scotland, the Lyttelton Harbour ;-Board's new dredger Canterbury ar--1 rivrd in Lyttelton Harbour enrly yes- ! tcrday morning, and after being passed Jby the Health Officer and the Customs ' officials, was berthed nt tho ferry : steamer wharf shortly after noon. The ! Canterbury was 111 days on the pas.----1 sa-c from tho Civile to Lyttelton, her limited coal capacity necessitating r.uui.v calls e:t route for bunker supplies. :>iie left -Renfrew on November 27th i.iM, and cleaicd the Clyfto two days later. Very heavy weather was exnoi noticed on the run down to the »^trr.it :oi Gibraltar, but tho proved herj scil an excellent tea-boat. j Captain J. Si.ewart, who brought- the G'sborne Harbour Board's dredge i .Muni to New Zealand, i.s in charge ni the CiiuLeil.-'.iry, -Mr J. W. i->J iite io ■ chief' t!iuj;iue.:r, and Mi , Curtis (-on oi' ; .Mr C Curtis, of Lyttelton) second ni- •; gineor. The crew will bo p.yid oif to- ; ilav, ami the Canterbury will be ofiiI o;;illy takru over by the Lyttelton llar- ' bom' Hoard to-morrow. Although she iis in ;;ond order after her lons trip, ! ns'seh v> ill have to be done before tin; Canterbury is ready tor work. She. will li;> t!iora'i'j,hly overhauled and clean-.-1 .md pnintod,* and will b<? docked for this purpose a? soon as the Manchester i vacates the dock. I NEW TYPE OF DREDGEK. [ The Canterbury represents a type of ! drod'-'cr that is entirely new to New I Zealand harbours. Sho is officially de--1 sivibed as a twin-screw, trailing suojtioii. and .seli'-nischarping, hopper i dre.drer, fitted with the Kruhling suo '• tion-hend and iot:>ry cutter. She is an • exceedingly int-restin;: "box of ina-i.-hirie.rv," V.nd her performances when I ,:lu' :-ta-ts arrive onerations in Lytlei--1 ton ILirbour, will *be closely followed iby all interested in harbour dredging I work in New Zealand. The v.;-s designed under tho direction "t Mr Cyrus J. K. Williams, len-'iiioor to th*> Lyttelton Harbour ' He:ird and v.:<s huiit by Messrs W llliam .S'.nnia'-? .!!!.! O.i , Ltd.. oi Renfrew. .The. rorntrurtion win curried out under the ili"i-:-tion <>f Messrs Carruthers and j Kiiiot, of London, repi-escnted by Mr X Ml K. A>lpv<irth, resident inspector nt fJenfie-.*. Tl!»; Canterbury was builfc ' under Lloyd's soc.-inl survey, wd to I their full rffjiiiri'inont."-:. ftho 's tho ■ :\mU .If.ibr- constructed in the yards J~i Messrs Sujvtv- and Co., and is the ivjvoMth dr.-d-er built-, by them for work jin New waters. The Canterbury differs from most other dredt'.cp in that she. does her j work «hilf>'steainiiiii, doing away witli ii(',> c!i'lay= of nickimt nn and dropping I moorinu.s. Her principal dimensions i nu> : _j jo!V -Ui (between perpendiculars). I ;>IH feet. bVend'th :\$ foot, depth l< fccUJ ■ incho*. Wm lias a hopper capacity ot ! '11 000 cubic feet, and "her speed, when i loaded, is about 8 knots per hour, j She is constructed to if red go to a I depth of 40 feet, and severe trials ! showed that is capable of_ loading I ]T2O tons of mud snoil in So to 4U> minutes. Her '-ladder," or suction frame, is hinged at tho deck level at, ! tho forward end of the. well, and is raised or lowered by a hoisting engine on deck, powerfully geared to a large winding drum. The suction-frnmo carries two pipes of 16in diameter, connepted to tho suction-head, tho Bin diameter shafting for driving the cutter, and a <sin pips for leading water to tho suction-head_. In tho engine-room are four sets or Dowerful compound engines, available for propelling tho vessel or driving tho suction-numns. nithrr independently or conjointly. On the voyage out the four engines were used for propelling tho vessel, two driving each screw. When dredging, the vessel will use j ho two after engines on each, side for steaming ahead, and tho other two for driving tho pumps. For lifting the spoil, there are. two large and very poworful centrifugal pumps of 16m diameter. Steam 13 supplied by two largo boilers, working at a pressure of 1301b to tho squaro inch. The stokehold is situated well forward of tho honners. Tho Frtihlintj suction-head is a massi to scoop. 10ft across, and fitted with heavy tooth. When dredging, this scoop, trails along tho bottom of tho harbour, and tho mud picked up by it, is lifted, by means of tho centrifugal pumps, through tho 16in suction-pipes, and delivered into th© honners. An independent centrifugal pump supplies water at 601b pressure to the euctionhead, by means of a 6in pipe branched nt tho head, and forces it through small jets close to tho cutting edge of tlio suction-head, to assist in loosening and softening tho mud for pumping. The hoppers aro fitted with a fielfdiscbarging arrangement. Tho samo pumps used for lifting tho mud do tho discharging. Tho material passes from tho hopnor through two tunnels into the discharge pipes, which are 22iu in d'umoter, and* is pumped to tho reclamation area. The "Canterbury is supplied with 500 feet of shore discharging pipo, but when she starts work, she will, for a timo, merely pnnin tho spoil over tho western breakwater, and discharge ifc into a shoot which is now being built. Tho dredgo is also fitted with tho ordinary hopper doors in her bottom, which aro worked by hydraulic pressure. A novel feature in tho Canterbury are the two Drysdalo compound centrifugal pumps ,which supply tho water to tho suction-head, and which by discharging water through valves on either bow assist to keen tho vessel steady when dredging. This latter contrivance, as well as all the deck machinery, is controlled from tho drodging master's bridge. The navigating bridge is further forward, and is fitted with tho usual appliances. Tho Canterbury is fitted with a very complete set or auxiliary pumps and machinery, including an electric lighting plant.