Swansea Marina salinity

The Swansea Community Boat Trust (SCBT) has recently obtained a vessel, The Black Prince, to undertake commercial cruises up the river Tawe from her mooring in Swansea Marina. Since her delivery in late 2010 a considerable amount of corrosion of her steel hull has been identified. Two possible causes of this have been suggested:

  1. Electrolysis between the steel hull of The Black Prince and the iron hull of the light vessel Helwick being expedited by the common electrical circuit between these two vessels.
  2. Incorrect selection of sacrificial anodes on The Black Prince for the salinity regime which it is experiencing at her mooring.

The purpose of this assist was to investigate the second of these possible causes.

Salinity measurements were taken during neap and spring tides at the mooring of The Black Prince in July and September 2011. All measurements taken showed the salinity to be considerably lower than the seawater concentrations which the anodes used on her hull were specified for, thus ameliorating their effectiveness.

Based on these measurements it is suggested that the SBCT consult specialists to select an appropriate sacrificial anode which is suitable for salinities of 0-10 PSU.