Over 200 jack-ups currently operating worldwide are designed for 350 ft water depth and above. In 2016 a large number of 350-ft-plus-class new builds are to be delivered, among which there are 17 CJ46 and 6 CJ50 GustoMSC designs. This paper explores how to extend the operating capabilities of these jack-ups by means of add-on spudcans, e.g. to operate in deeper waters, to withstand higher environmental loads or to carry more variable load.
The effectiveness of add-on spudcans to increase the water depth capability is demonstrated by performing generic Site Specific Assessments (SSA) for the CJ46 and CJ50 jack-ups using generic Gulf of Mexico (GoM) environmental and soil conditions. The presented SSA for these two designs shows opportunities to extend the water depth capability by 50 to 80 ft.
The paper also shows how a CJ50 jack-up can be made suitable to operate in deeper waters as well as to withstand higher environmental loads than originally designed for using typical North Sea harsh-environment and soil conditions. The SSA presented shows that a CJ50 fitted with add-on spudcans can withstand higher environmental loads up to a maximum wave height of 85 ft together with a water depth increase of 110 ft.