MORETON BAY AND BRISBANE RIVER.
The banks at the northern entrance to Moreton Bay are constantly shifting, and the maintenance of the necessary lights and buoys to enable vessels to enter and clear the port in safety is a source of continual anxiety. The floating beacon, which had broken adrift during the month of February, disappeared altogether on the 10th March; and although diligently searched for, no trace of her has been discovered. Two valuable buoys disappeared from the outer banks about the same time. The floating beacon has been replaced by a new second-class (Trinity pattern) steel conical buoy, surmounted with a staff and cage, the top of which is 12 feet above the water, forming a most conspicuous object. New buoys have been moored in the positions of those lost.
No. 1 cutting, Hamilton Reach, has now a depth of 17 feet at low water, spring tides; and the entrance to the bar cutting is being dredged to a similar depth. The increased depth of water in these cuttings is of considerable importance to vessels of heavy draught. A depth of 15 feet at low water, spring tides, is fully maintained in the other cuttings, but there are several shallow places in the town reaches of the river which require attention.
The more recent gales and floods do not appear to have injuriously affected the dredged cuttings of the Brisbane River. Several new beacons have been erected to replace those blown down or found defective; and, to render them more conspicuous, heads have been placed on some of the beacons marking the bar cutting. Beyond some slight repairs, now being effected, all the sea and river marks for the navigation of this port are in good order, and the various buildings are not likely to require any extensive repairs for some time.
The apparatus at the various lighthouses in Moreton Bay are in good order, with the exception of the reflectors at Cape Moreton, which will shortly require re-silvering. This work can be done locally.
The sea-pilot steamer "Advance" continues to do her work satisfactorily, and is most usefully employed at her present station. She is only used for towing in cases of emergency, so that her earnings in that respect are very limited.
The "Laura" is a most useful vessel, and is kept fully employed performing the various duties of the Department. She is, however, seventeen years old, and her hull shows signs of weakness, although her engines and boiler are in good order.
The "Pippo" requires a new boiler and certain repairs to her hull. To efficiently carry out the work of the Department at this port, I find a third steamer indispensable, as the "Advance" must be kept at her station, and it is impossible for the "Laura" to successfully perform all the other work of the Department; and should either break down, a third steamer would be necessary as a relieving vessel.
The Nautical Surveyor (Mr. E. A. Cullen) has just finished a survey of the northern half of Moreton Bay, a work which was rendered necessary by the fact that the only chart available for use was one originally published by the Admiralty in 1865, with corrections inserted at various intervals up to within the last two years, since which great changes have taken place in the formation of the banks. Mr. Cullen accomplished the work in the "Pippo" in a most satisfactory manner, in the short space of five months, and a tracing of the new chart has been transmitted to the Admiralty for publication. The survey discloses changes of a prejudicial character at the entrance to the North or Howe Channel, which has been contracted by the extension of the east bank in a northerly direction about four cables, and the south-east extreme of the north bank to the eastward, about three and a half cables, while to the north-north-east of the north bank a small patch has formed, having only three fathoms upon it at low water. This patch is only one cable to the westward of the line of lights, and a continuance of similar growths will render the entrance at night exceedingly difficult, and probably destroy the utility of the present leading lights. The channel, however, at present maintains a depth in its shallowest part of 21 feet at low water, spring tides. The attached plan shows the position of the line of lights in relation to the three fathom patch and north-west extreme of the east bank. The three and five fathom contours as existing in 1886 are shown in red, while their present positions are indicated in black. Numerous other changes are shown on the new chart, but the banks to the westward, in the vicinity of the north-west channel, have changed so very little during the last twenty-five years that the channel may be regarded as practically a permanent one. It is the widest, deepest, and only permanent approach to Moreton Bay, and vessels of heavy draught, whose visits are rapidly increasing—including some of H.M. ships—have now to wait for daylight to enter the port by this channel. It is buoyed for use in the daytime, and can—when considered necessary—be easily and cheaply lighted for use at night.
The approach to Moreton Bay by the South Passage should be discouraged, as the banks move about in a remarkable manner; and variation in the depth of water and direction of the channels being of frequent occurrence, it should be attempted only by men possessing good local knowledge, in vessels of light draught.