D.—3

1891.—Suss. 11. NEW ZEALAND.

GISBORNE HARBOUR-WORKS (REPORT ON, BY MARINE ENGINEER, TOGETHER WITH COPIES OF DRAWINGS).

Presented to both Houses of the General Assembly by Command of His Excellency.

The Mabine Engineeb, to the Hon. the Minister having ohaege op THE MAEINE DePABTMENT. Sib, — Marine Engineer's Office, Wellington, December, 1890. In pursuance of your instructions, I have the honour to report on proposed harbour at Gisbome. I inspected the works as now existing in August last, but the more immediate urgency of works actually in progress in other parts of the colony has prevented, until now, my devoting the amount of time and consideration to the Gisborne question that the difficulty and importance of the case required, before I could report upon it. Sir John Goode's Design. The works proposed by Sir John Coode, in December 1880, for a harbour at Gisborne, as indicated on map herewith in brown, consisted of a sea-mole with sheltering jetties, connected to a solid root on shore by an open iron viaduct; and were designed to commence about 50 yards to the east of Maori Point, and to run out from thence in a (magnetic) south-west direction for 2,460 ft., thence curving into a direction west by south for a further length of 400 ft. Total length of sea-mole, viaduct, and root, 2,860 ft. The jetties were to project from either end of the sea-mole, and were each to be 430 ft. in length. Of the 2,860 ft., a length, at shore end, of 550 ft., reaching to low-water line, on the bare " papa " rock, and constituting the root of the structure, was to be solid work, composed of rubble and debris with masonry facing ; the sea-mole, 900 ft. in length, was also to be solid work, composed of concrete blocks ; and the intervening viaduct was to have a length of 1,410 ft., consisting of fortyseven spans of 30ft. each. The jetties were to be solid work, consisting of rubble and debris with timber-facing. The length of sheltered quay which this design provided for would have been 1,600 ft., having a depth of 21ft. to 30ft. at low water of spring-tides. The estimated cost was as follows:— £ & Root, of rubble and debris —Length, 550 ft. ... ... 10,750 Iron viaduct, „ 1,410 ft. ... ...- 48,980 Sea-mole, „ 900 ft. ... ... 135,180 2,860 ft. 194,910 Jetties"( 2) „ 430 ft. (each) ... ... ... 51,490 Total ... ... ... ... ... ... 246,400 As regards the undesirability of a continuously solid mole, Hir John Coode says : — "Having regard to the great extent of sandy beach within the bay, extending, in fact, for several miles to the southward of the town and river-entrance, and also to aspect and exposure of the bay itself, I am unable to recommend any solid structure between the shore and the line of 3 fathoms at low water, feeling assured, as I do, that a serious amount of sanding-up, on the inner or western side, would inevitably follow, and to an extent that, to say the least, would be highly prejudicial to the present river entrance, and to the utilisation of the new work." The reason for thus going into detail as regards Sir John Coode's design will be apparent further on. Design as authorised. The works authorised to be constructed in lieu of Sir John Goode's proposals, as indicated on map herewith in green, consist of— (1.) A timber wharf and viaduct extending along river-side in a south-west direction from the blookyard to low-water line, length 1,580 ft. (2.) A solid concrete mole, in line of wharf .and viaduct produced, from low-water line for a length of 1,900 ft., and thence curving into a direction west by south for a further length of 250 ft. Total length of concrete mole, 2,150 ft. I—D. 3.