First of all, The most important thing to pay attention to jacking operation for Vessel.
Always keep track of the ship’s draft , sea level, seabed , and the position of the Spudcan, which is the tip of the leg.
You should also have tidal information for the site.
It is necessary to complete SSA (Site Specific Assessment) wherever you want to jacking.
And need to get Location approval from MWS (Marine warranty surveyor)
In addition, It is necessary to confirm the conditions during the jacking operation determined by the vessel(or rig) design.
Also, It is necessary to create a preload plan beforehand
Bring the Vessel to the specified position with DPS or towboat
Lower all legs at once.
Leg load increase when the putcan touch the seabed.
Vessel draft also rises.
At that time, it is necessary to to check the value of RPD( rack phase differential)
If there is an abnormality in the RPD, Since the leg may be twisted,
It’s better to pull out the leg and release the stress.
When the draft reaches the reference position
Need to change seawater intake from Seachest to RWP(raw water pump)
(Raw water pump position should be monitored at all times during operation)
Raise the hull to the pre-determined preload position
Preload is divided into at least two stages, Active and Passive preload.
(Depending on the site, it may be necessary to decide it into more)
