Wightlink’s replacement ferries, Information to support an appropriate assessment of their likely environmental impact.

The marine environmental agency ABP Mer prepared this Report on the probable effects on the environment of Wightlink’s replacement ferries between Yarmouth and Lymington.

The Report has concluded that the contribution to inter-tidal erosion in the estuary from ferry waves is not significant.

The Report states that there is a lot of evidence from separately produced analyses, models and surveys that confirms our understanding of the scale of the changes that are likely to occur from the introduction of the new
Wight class ferries.

The Report listed a number of reasons for having confidence that the new ferries would have no greater environmental impact than the current C class ferries:

• The new W class ferries are predicted to create ferry wash waves of a similar magnitude to the existing ferry operations at equivalent speeds, not greater ;

• The contribution of ferry waves to overall wave energy within the estuary is very small;

• The maximum height of ferry waves is much smaller than that of wind waves within the estuary; and

• The energy associated with ferry waves is not large enough
  to cause erosion of inter-tidal areas.

The Report identified the capital dredging that took place in Lymington Harbour in the 1970s, to create the yacht marinas, the natural meandering tendency of the estuary and greater wind-wave penetration into the estuary as factors causing erosion of the inter-tidal mudflats and salt marsh – rather than increased ferry-wave activity. The Report also found that cliffing of Spartina marshes at the mouth of the estuary had increased their vulnerability to lateral erosion.

There is good news for conservationists, as the Report states with ‘high confidence’ that there has been no substantial change to the mean low water alignment along the estuary since, at least, 1994.

The Report concludes that, in total, the evidence should provide the statutory authorities with a high level of confidence about the findings of the assessment. Allied to this are the control recommendations presented by BMT Sea Tech (2008), which will assist with the management of navigation on the river.

Overall, Lymington Harbour Commissioners’ risk assessment provides a framework within which the ongoing activity of the ferry service can be integrated such that the needs of all users of the estuary can be taken into consideration as part of the on-going management of the Harbour

Download the full report (14mb PDF right click and "save as") >