A report produced by independent consultants into how Douglas harbour could be developed for a deep water berth has been published.

A harbour strategy approved by Tynwald in March last year included £11m plans to deepen the berth on the north side of Victoria Pier to cater for 240m-long cruise ships.

More ambitious proposals for a 450m-long deepwater berth outside Princess Alexandra Pier were rejected on cost grounds - but not ruled out should the cruise business take off.

ABP Marine Environmental Research - part of Associated British Ports - was commissioned by the ports division to look into both options. Modelling of the Victoria Pier Berth scheme showed that dredging the berth to 9.5m below chart datum will have negligible effect on existing tidal flows and on the volume of silt building up within the berth - so there will be no need for maintenance dredging.

Construction of a new deep water berth will similarly have negligible sedimentary effects on Douglas harbour, ABPmer found, and the requirement for maintenance dredging will remain negligible.

But vessel simulations indicated that in both cases manoeuvres conducted in conditions above Force 4 become increasingly difficult.

A standard cruise vessel would be unable to depart from an expanded berth at Victoria Pier during easterly wind conditions above Force 4 without tug assistance.

AFBmer recommended that two tugs should be used for departures during easterly wind conditions.

In relation to a new deep water berth, the report notes: ’Ebb tides and following winds require greater speed to maintain steerageway on approach to the deep water berth.

’This impacts on the control of the vessel when making turns and reduces the margin of error when taking way off.’

It adds: ’Tug assistance is advisable for all manoeuvres conducted, especially in conditions above Force 4, for both proposed berth schemes.

’The conditions and limiting factors for tug operations and connecting lines should be considered in conjunction with the limiting factors of vessel operations.’

The Department of Infrastructure is considering the next series of studies and is in discussions with various maritime parties on-island.

A report by the environment and infrastructure policy review committee, debated by Tynwald in December, concluded that the process of delivering the strategy to parliament was ’premature’. It said that many aspects of the strategy were ’ill-thought-out’.

And the report said the determination to focus on cruise ships through the Victoria Pier proposal meant ’other opportunities have been closed off and not fully considered’.

Tynwald unanimously approved the first recommendation of the report that the DoI should focus on progressing maintenance works for Douglas harbour as a matter of urgency.

But it rejected the report’s other recommendation that there should be an external strategic review of the island’s harbours and options for future development.

The Council of Ministers said it could not support an external review, given that Tynwald had only recently debated and endorsed the harbours strategy.

Infrastructure Minister Ray Harmer told Tynwald in December: ’The detailed work done validates the views of those who advised the department the siltation was not going to be a problem, that some strong winds would be a problem for large cruise vessels and that navigating into the berths was possible but would in some conditions require assistance.’