Saltwater Engineering completed the strength calculations for the integration of a 100 ton lifting capacity crane onto the main deck of an offshore support vessel. The integration was complicated by the fact that the client did not want any constructive works to be completed in the existing hull of the vessel. A new constructed deckhouse is built around the column in order to absorb the induced moments.

Calculation model

Crane column model

The crane column and deckhouse along with a large section of the hull has been modeled in the FEM package SCIA ESA PT. In this model all loads and load combinations along with the safety factors are taken into account. In order to ensure a smooth transition of the stresses from the crane column into the hull the bottom of the column had to be built as a transition piece, changing the cross section of the crane column from circular to rectangular.

Deformations

Stresses in crane column

Stresses in deckhouse support girders

After completion of the calculations a detailed report was presented to our client which will form the basis for the completion of the production drawings for the final integration of the crane column.