Summary of Royal Lymington Yacht Club Presentation

Posted on 23 Apr 2008

The Club welcomes the report of Lymington Harbour Commissioners’ BMT Phase 1 risk assessment study. Our interest in the overall risk assessment is the impact of the new ships on leisure users of the River, leaving environmental matters to the Solent Protection Society and others.

We welcome the finding that the ships will not need to slow down in Horn Reach creating increased disruption to our events there. Lower speed limits were originally proposed by Wightlink’s Eagle Lyon Pope study released last September.

We welcome the recommendation that there is to be no change to the regulatory framework that applies to organised sailing events. These issues were major concerns for the Club and we are happy to see them set aside, subject to any revision as a result of the appropriate environmental impact assessment.

There are two remaining areas of concern to the Club the report addresses though not conclusively.

The W Class ships’ larger side profile will create a larger wind shadow than the C Class. We require competent novice sailors to be able hold a small dinghy head to wind for about 30 seconds while a ferry passes. The report predicts a doubling of the time for which a ferry creates disturbed air as it passes: up from 10 to 20 seconds at 4 knots passing speed; up from 20 to 40 seconds at 2 knots.

These increases represent a significant erosion of our safety margins.

Increased wind shadow will also have an increased adverse effect on all leisure users of the River, especially sailing boats without engines and on the downwind ferry if ferries pass in Short Reach as has been proposed.

Wind shadow will get further attention in the sea trials but we doubt it will be possible to collect data in trials run over a relatively short space of time to produce the range of data that would properly inform a full risk assessment into the consequences of increased wind shadow.

We have suggested to Lymington Harbour Commissioners that without wind tunnel testing they will be unable to predict the effects of wind shadow on other river users or properly assess the risk of the new larger ferries passing in the River.

The second area of remaining concern is the impact of the larger, more powerful Voith Schneider drive units. The report predicts a 20% increase in side thrust derived from the increased speed of the jet and an additional though un-quantified increase in the jet cross sectional area. The report does not add these observations together: in the absence of that, it is difficult to avoid the conclusion that side thrust will be very substantially higher.

Increased side thrust will impact other users of the River in a number of ways. It presents an increased risk to passing and moored vessels and potential for hazardous interactions between passing ferries – if that is to continue – and potential for increased environmental impact. We expect to see this issue more fully dealt with in the next phase of BMT’s work.

Our concerns about side thrust, windage and other factors predicted in the report underpin our long standing concerns about the safety of passing in the River.

The BMT Phase 1 project is very important to leisure users of the River. It has its origins in a meeting held between the Club and Wightlink last September. Wightlink had just released the studies into the navigational and environmental aspects of the new ferry but no comparable work had been done to back the company’s claim that the new ferries would have no increased adverse impact on other River users.

Wightlink kindly offered to consider funding such a study and we produced terms of reference which we discussed with Lymington Harbour Commissioners. The Commissioners decided that such a study should be funded by them, in essence bringing forward some of the work they had planned to do nearer the time of the sea trials.

We were delighted with this response for three reasons: a competent, expert study was to validate our concerns; the independent consultants selected were a firm known to us as leading experts in the field and they were to work to our terms of reference.

The BMT Phase 1 study and its continuation in the second, sea trial phase will help give sailors the confidence that all their concerns have been listened to and that consideration is being given as to how to mitigate the increased adverse impact on our activities.

There is, however, some way to go to achieve the aim of no increased adverse impact on leisure users of the River and if some adverse impact remains, sailing will adapt as necessary and, in that event, I’m confident we will be able to establish a constructive dialogue with Wightlink.

It is the Club’s aim for us all to be able to go forward working harmoniously together for the benefit of all River users.

Finally, I would like to express the Club’s gratitude for the thorough and professional way in which Lymington Harbour Commissioners are assessing the new ships. We are confident that they will continue to act in the best interests of all the users of our unique River. In this, they and their consultants have our full support.

Geoff Holmes Commodore Royal Lymington Yacht Club