Clearing the bar

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Maintaining clear access to harbours is a critical part of promoting safe boating.

Much of the focus on improving access to boating is on coastal infrastructure projects such as boat ramps, wharves and jetties. These are rightly regarded as essential elements in making it easier for people to get on and off the water. Equally important, however, is the on-water access and how safe or practicable it is for boaters to get where they want to go. Harbour bars are a prime example as they can often create dangerous conditions for boats to negotiate, particularly small boats, increasing the risk of something going wrong or restricting access to open waters.

Dredging of safe access channels is typically the responsibility of local councils but, in many cases, these councils lack sufficient resources to carry regular dredging programs. Funding sources such as NSW’s Boating Now program help meet the cost of one-off infrastructure projects but not on-going maintenance of the seabed. Environmental concerns about the impact of dredging on local eco-systems also mitigates against anything but the most significant projects getting the ‘green’ light. And while nobody wants to see the environment permanently damaged by dredging, the approvals required to ensure that doesn’t happen make getting such work done that much harder.

A new approach

So what can be done? Stuart Ballantyne, a keen boater, naval architect and director of Sea Transport Solutions, has looked at the issue of dredging and seabed maintenance and come up with a number of proposals which he believes would make it easier for regional harbours to carry out routine clearing operations (check out his presentation here). In essence this involves the use of smaller, more mobile and more efficient dredging vessels capable of carrying out small-scale operations on a regular basis.

According to Ballantyne, current dredging equipment is not suitable for small-scale deployment because it can’t be used in certain conditions (e.g. swell or heavy current) or shallow water, it’s too big or too expensive to be economical, and the equipment is often unappealing to look at, e.g. the Pioneer and Boral aggregate dredgers on the Brisbane River were regarded as an ‘eyesore’ when working close to residential areas.

The types of dredging vessels he envisages would be small-scale, such as a 35m utility vessel, offer a range of seabed maintenance techniques to suit the type of works being carried out (eg rainbowing, trailer suction, cutter suction, hydro bed levelling), be easy and economical to deploy, aesthetically pleasing to look at as well as safe and ergonomical for the crew to operate. They would also incorporate the latest seabed scanning systems for mapping the local topography and determining where and how to dredge.

Ballantyne has identified more than 120 harbours around Australia that could benefit from having safer boating channels cleared through their bars. Such a program of dredging – Ballantyne calls it a Nation Building Initiative – would deliver a number of benefits, aside from making it easier and safer for boaters to get on the water. Better access helps to boost tourism and generate jobs, says Ballantyne, highlighting the example of the Southport Seaway on the Gold Coast which, prior to 1986, was a dangerous bar and which now sees hundreds of vessels using it every day for commercial purposes – whale-watching, diving, fishing, sailing etc.

Dredging can also help to reduce the impact of flooding, for instance the dredging planned for the Burnett River at Bundaberg which has been subject to devastating floods in recent years. Where clean fill is available, it can also provide councils with a ready source of sand (currently costing about $18-$25 per tonne in bulk). Ballantyne proposes that councils should be permitted to clear existing boat ramps of up to 1,500m³ of sediment each year while additional permits for 9,000m³ per annum (sufficient for a 85x35x3m channel) should be granted to enable extraction at river mouths at four or six monthly intervals.

While such a scheme might eliminate some of the excitement of a choppy bar crossing, the flow-on effects in terms of stimulating boating activity would no doubt be significant as well as potentially life-saving by reducing the risk of accidental grounding or capsizing.

This article was first published in the February-March 2018 issue of Marine Business.

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