Small-craft harbour hinges on boat owners’ support

Press, 31 March 1981, Page 3

Small-craft harbour hinges on boat owners’ support

Shipping reporter

After years of talk, study, design, and testing, the Lyttelton Harbour Board is prepared to go ahead with the development, of a small-craft harbour at Magazine Bay if the required interest and financial support can be gained from boat owners. Inner-harbour berths for, small craft have- been ini short supply for years. The ; first proposal for using i Magazine Bay was mooted in 1926.

Prospective berth holders, however, will have to dig deep to finance the scheme, which, in accord with Ministry of Transport guidelines, will be paid for on a userpays basis. The prepayment for a berth in the new marine could be as high as $lO,OOO, as well as an additional annual maintenance fee. The costs will be determined on the basis of the amount of interest shown in the scheme.

The chairman of the board, Mr J. E. Mannering. said: “The board is pleased to be able to promote the development of additional facilities for small craft, but the provision of the berthage area and the level of facilities provided will depend on the support from the prospective berth holders themselves.”

The decision to proceed with the scheme comes after months of testing rubbertyre breakwater systems.

[Traditional rubble mound or , other solid-fill breakwaters have always been considered too costly, because of the soft bottom of the harbour inlet and the depth beneath mud level of rock or other firm material on which such structures could be based. The rubber-tyre idea first came to light in the United States about seven years ago, when a leading tyre manufacturer began to examine environmentally acceptable ways to dispose of used tyres. Investigations were done regarding breakwaters, and were followed by years of research and testing in the United States, Scotland, Canada, and Australia.

Lyttelton Harbour Board engineers decided in 1978 that such a system might prove feasible at Magazine Bay and undertook the design, building, and testing of a prototype breakwater.

Observations were made of wave energy reduction, especially during south-west storms, and a close check was kept on the materials used to tie the tyres together. Converyor-belt strapping and nylon” bolts were used to form the tyre modules and to assemble the modules into the breakwater.

In May, 1979, a 45in by 15.7 m breakwater was constructed in the board’s graving dock, towed to Magazine Bay, and secured in place. In February last year the

breakwater was towed back to the graving dock for investigation. its wave-dimin-ishing qualities having been determined as satisfactory. It was found that a great deal of marine matter had adhered to the tyres and had, in fact, caused some of the modules to submerge. The tying materials were found to have performed well with only a few minor abrasions. The marine matter on and in the tyres was inspected by Professor G. A. Knox, of the University of Canterbury, and an environmental report prepared. Buoyancy was then the remaining problem. Overseas information was again consulted, and several flotation materials tested for six months beginning in May, 1980. After a moderate storm had shifted some of the mooring blocks, design changes were made. Bigger and heavier blocks were installed and mooring lines extended. According to the board’s chief engineer, Mr J. B. Bushell, no additional problems were encountered. Two flotation materials were found to be completely satisfactory, both incorporating polypropylene foam. While there will be maintenance expenses which would not be encountered with a solid breakwater, the initial cost is about onesixth less, according to Mr Bushell. The environmental impact

assessment for the development of the facility was: issued earlv in March. Sub-, missions will be received I until April 16. The extent of the first: stage of the development could provide as few as 50 berths, but that number is considered to be the minimum. A finance scheme has been adopted by the board which allows for a 50-yeari depreciation of the facility, i “The costs associated with! the development are directlyi connected with the level of< interest shown at the first! stage,” said Mr Bushel!. It is hoped that, should sufficient support for a berthage facility be obtained, the following” berth costs would apply:! 0 to 8m length berths $5954;| berths 8 to 10m, $6500; 10 to 13m. $8294; and 13 to, 16m, $9412. J The amount of annual! maintenance costs paid by the berth holders would again depend on the interest shown, and the size of the facility. Subject to sufficient support and approval of the environmental aspects of the development, the board es timates that the earliest formal licence agreements could be entered into by August or September of next year, with the first prepayment to be made by September 30, 1981. If such a schedule can be adhered to, the board expects the first berths would be available by mid-1982.