TIMARU HARBOR BOARD.

Temuka Leader, Issue 2661, 19 May 1894, Page 3

TIMARU HARBOR BOARD.

THE NEW TUG DREDGE. The following is the conclusion of Mr Barr’s report on the new tug-dredge:—■ “ The question next arises as to the probable output and cost of working this plant, and the data obtained in the trials and the general character of the plant afford sufficient information to allow a pretty accurate approximation to be obtained. “ The actual result in the hopper when the dredge was working in shingle and sand outside the harbor was at the rate of 177 tons per hour, which, of course, takes no count of the sand which was carried overboard before it had time to settle. Making allowance for the' difficulties of work at that part, I believe that it is safe to accept the working capacity inside the harbor at 250 tons per hour, which is a long way under the amount which calculations based upon her guaranteed delivery of water and the proportion of solid found by experiment would give. Her daily yield would therefore be 2000 tons, or in a year of 300 working days a total of 600,000 tons ’ as there would be time occupied in mooring, repairing, and by other causes, I will not calculate upon a greater annual yield than 250,000 tons ; a quantity which I have no doubt can be obtained if the material be pumped away from the dredge when it is of a character which will not precipitate in the hoppers. The annual cost, exclusive of interest and depreciation of plant, but including all charges for wages, fuel, stores, repairs, etc., I place at £4260, or equal to 4d per ton. 1 have a hope that the cost will bo less than this, seeing that in 1891 one dredge in Newcastle harbor (N.S.W.) pumped ashore 513,000 tons of stuff at a cost of 2.18 d per ton ; and in the same year another dredge in Sydney harbor similarly disposed of 324,000 tons at the rate of 1.97 d per ton. These dredges worked 10 hours per day and the material is described as ‘ sandy silt.’ “ In this calculation the whole cost is charged against dredging, but as you propose to employ the vessel in towing, the revenue derived from this would be a set-off in favor of the plant. “ I hud on reference to your last annual accounts, and from figures kindly furnished to me by your secretary and by your inspector of works, that the Tauiwha last year dredged and convoyed outside the harbor a total of 17,570 tons of spoil, stones, and shingle, the total working expenses of the craft being £1325, of which, after allowing for what was done for ships’ ballast, there would lie £ll oO chargeable against dredging, or about Kiel per ton. A comparison, therMerc, of tho actual performance of that vessel with what may reasonably bo expected from the new plant shows largely in favor of tho latter. “ If tho material should bo shingle, and carried out to sea, the estimate of cost would not be much different.

“ It is now necessary to consider what would bo the oust of extra plant to allow of the spoil being pumped to some distance from tho vessel, and 1 may

remark that in your circumstances the extreme lead which will be necessary is considerably shorter than has been successfully negotiated in many other places. [The remainder of this report is un‘ avoidably held over]. l