Westhaven Marina Proposed Pile Berth Redevelopment Navigation Safety Report
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Westhaven Marina Proposed Pile Berth Redevelopment Navigation Safety Report Capt. Jim Dilley, Master Mariner 1 Contents INTRODUCTION ....................................................................................................................................... 3 EXECUTIVE SUMMARY ............................................................................................................................ 5 EXISTING SITUATION ............................................................................................................................... 5 Western Entrance/Exit ........................................................................................................................ 5 Navigation at the entrance ............................................................................................................. 6 Area outside the entrance .............................................................................................................. 7 Other traffic .................................................................................................................................... 8 Harbour bridge traffic ..................................................................................................................... 8 Race starts ....................................................................................................................................... 9 Risk assessment .............................................................................................................................. 9 Berthing ......................................................................................................................................... 10 Eastern Entrance/Exit ....................................................................................................................... 10 Navigation at the entrance ........................................................................................................... 11 Pile Moorings .................................................................................................................................... 12 Marina Fairways and Traffic Hubs .................................................................................................... 12 PROPOSED SITUATION .......................................................................................................................... 14 Construction ...................................................................................................................................... 14 Marina Berths ................................................................................................................................... 15 Closure of Western Entrance ............................................................................................................ 15 Vessels affected ............................................................................................................................ 15 Berthing ......................................................................................................................................... 16 Marina fairways and traffic hubs .................................................................................................. 16 Oil spills ......................................................................................................................................... 17 Start box ........................................................................................................................................ 17 CONCLUSION ......................................................................................................................................... 18 Recommendations ............................................................................................................................ 18 2 INTRODUCTION This report discusses potential navigation safety implications that could arise from the construction and subsequent operation of the redevelopment of Westhaven Marina, hereafter referred to as the Application. The Application includes an extension for the western breakwater to connect to the eastern breakwater to provide public open space and parking. The public open space has been designed in conjunction with local iwi. The proposal also includes the conversion of existing pile moorings to pontoon berthage. (see Fig. 1 and the Westhaven Marina Proposed Occupation Area Fig. 2). Figure 1. Proposed re-development: Breakwater extension Pontoon berths 3 Figure 2. Westhaven Marina Occupation Area The term navigation safety refers to the safety of a vessel or vessels interacting with: another vessel or vessels; the seabed; a structure; a natural object, such as rock or the foreshore; or any combination of the above. As such, as soon as one vessel is operating in an area, there will be navigation safety issues. Navigation safety issues may be minimized or reduced to an acceptable level, but cannot be completely resolved if vessels are operating in an area. Navigational Safety Management is the system of criteria, standards and competence that maintain the ability of a vessel or craft to navigate safely in confined waters such as are found in harbour areas. The most recent occupation permit has addressed this matter to an extent by delineation a vessel transit area (refer Fig. 2) The New Zealand Port and Harbour Safety Code (the Code) was introduced in 2004. The Code brings together a succinct digest of the formal duties and responsibilities of participants in port and harbour safety and a corresponding statement of the specific measures appropriate to their fulfilment. A critical component of the Code is safety management systems based on risk assessment. The Code has been adopted by the Auckland Council and a Code Application Assessment, Risk Assessment and Safety Management System has been developed. The assessments and Safety Management System have been approved by Maritime New Zealand and are under continual review and audit. The Safety Management System sets out how the Auckland Council, through the Harbourmaster, manages the safety of navigation. The risk assessments assist in identifying where possible risk may exist and how control measures may help in the mitigation of a risk. The Auckland Region Risk Assessment 4 and its annual review (the Risk Assessment) (excluding the operation of shipping to POAL wharves and the operation of RNZN vessels and berths) is undertaken by the Harbourmaster. Navigation safety issues in the Waitemata Harbour are part of this Risk Assessment. EXECUTIVE SUMMARY The proposed re-development has built on existing good practice and international standards to provide a practical and effective use of existing space. The increase in the safety of navigation both within the marina, and in the area immediately to the north of the marina, is evident. The only possible adverse effects are a small time inconvenience to some of the vessels that use the western entrance, and a small percentage increase in traffic volume at the eastern entrance. Overall, the proposal provides an appreciable increase in the safety of navigation in the area and provides for manageable and accessible berthing of vessels. The possible effects of any construction and ongoing maintenance and dredging work are easily managed in line with current good practice. I recommend the movement of the Start Box to the east as suggested in the proposal. EXISTING SITUATION At present, vessels may enter or leave Westhaven Marina through one of two entrances, the western and eastern entrances (Figs. 3 and 5). Western Entrance/Exit The western entrance/exit (hereafter western entrance) is approximately 60 m wide1 (see Fig. 3). On either side of the gap are rock breakwaters, which extend at an angle underwater thus, reducing the effective width of the channel. The wider western breakwater has a gangway for access to marina berths on pier A extending at an angle2 (see Fig. 3). The fairway in the marina adjacent to this entrance is approximately 60 m wide. The entrance is marked by aids to navigation on both sides (lights: Oc.G.5m5M and Oc.R.5m5M). There is a tidal flow during the flood tide through the entrance of approximately 0.2 m/s (0.4 knots).2 Outside the entrance the flood tide flows west and the ebb tide flows east, at approximately 2 knots.3 There is 1 Proposed Westhaven Pile Berth Redevelopment (Stage 1) Design Report. Beca Ltd 5 August 2015, Fig 1. 2 Ibid., p.10. 3 Chart NZ5323 5 an extreme significant wave height through the western entrance of 0.95 m.4 to the west of the entrance is an area of shallow water (<5 m) marked by a red buoy (see Fig. 4). The western entrance provides a route for vessels in the marina navigating to, and from, destinations to the west in the upper harbour and the start line for yacht races, which is shorter than using the eastern entrance. Vessels may also use this entrance to navigate to, and from, areas to the east (the Hauraki Gulf). This is likely to be the vessels berthed immediately adjacent to the entrance i.e. only the vessels in the berths of row A and the western pile moorings in the 100 series berths have a shorter distance to travel using this route rather than the eastern entrance. Once outside the western entrance, vessels are restricted to a speed of 5 knots within 200 m of the shore and to 12 knots in the harbour. This speed restriction means that vessels traveling outside the marina are unlikely to reach a point opposite the eastern entrance