Polaris gets Customised Docking Blocks in Cape Town

There were a few options as to where the Stolt Offshore "Seaway Polaris" thruster inspection and refit would take place. Cape Town was a strong contender - but not without some interesting problems which had to be solved first. The Cape Town Sturrock dry dock is owned and operated by the National Port Authority, who do not engage in any ship repair works, so the procedure for securing a position in the dry dock is different to most other places in the world where the successful shipyard would dock the vessel in their own dry dock.

The thruster removal procedure required the centreline block height of the barge to be 3,8m. The Sturrock dock standard blocking line height in the centre of the dock was 1,4m, and the National Port Authority would not consider any other block height.

Anton Wale & Associates were asked in March 2002 if they were prepared to engineer - at risk - a solution for the increased blocking line, with the understanding that if the vessel was going to be dry docked in Cape Town, they would get to design & supply the blocking line.

By 15 March the first proposal was submitted, which employed a combination of a 100 te SWL concrete base piece with the NPA standard blocks on top. This was soon modified to a single 100 te SWL concrete column with cruciform base and vessel bearing pad the same dimensions as the NPA.

After many more hours of deliberation, the final design was submitted on 10 April 2002. This solution employed approximately 144 reinforced concrete blocks, each with a SWL of 200 tonnes and a mass of approximately 8 tonnes - as shown in the pictures above.

The fabrication time for blocks was 7 weeks.