Ease of Biofouling Removal

In several inspections of the first 90-10 copper-nickel hull, the Copper Mariner, the majority of biofouling attachments have been dislodged apparently during the 3-8 knot travel to and from shrimping grounds and any remaining could be flicked off with a thumbnail. The attachment when it does occur is very light compared to the manner in which barnacles embed themselves onto steel, titanium and other materials without significant biofouling resistance.

This has also been confirmed from more recent trials at Langstone Harbour, UK, by IMI Yorkshire Alloys Ltd, which not only showed the ease that the fouling could be wiped away but also the ease with which fouling could be removed compared with steel even when cathodic protection was applied and a sizeable fouling build up had occurred on the test panels6.

The latter has also been observed by divers in the Morecambe Field when cleaning legs which have been sheathed with 90-10 copper-nickel for splash zone corrosion protection. The Morecambe Field is a major gas field in the Irish Sea. In 1984, copper-nickel was used to cover legs on production and accommodation platforms, three drill platforms and a flare stack.

The sheathing was welded directly to the steel and spanned +13m above Lowest Astronomical Tide (LAT) to -2m below LAT. The sheathing was 4mm thick annealed sheet. The legs were cathodically protected which allowed fouling of the 90-10 copper-nickel.

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