Extends the weather window for safe offshore crane operations by measuring accurate motion on the cargo deck

System description

The Deck Motion Monitor (DMM) displays the Effective Significant Wave Height and real time waves on the vessel deck. Accurate information from the DMM may allow lifting whereas the traditional sea state method would normally overestimate the motions and not allow lifting operation.

Using the DMM system will increase safety as well as operational availability to all offshore lifting operations. In particular during heavy lift operations, where the risk is higher and margins for error are smaller, there is no room for guessing.

The system has several stand-alone moduels for various operations; DMM-Personnel, DMM-Relative Motion, DMM-Deck View, DMM-Simulator Mode and DMM-Seakeeping. To read more about these modules, click on the menu on the right.

DMM – Ease of Use

The DMM system is designed for usability, ensuring that the interface has elements that are easy to access, understand, and use. Conducting a safe crane operation requires experience and accuracy. As the DMM system allows operation in a wider range of weather conditions, it is crucial that accurate data is presented in an intuitive manner.

The main display consists of three elements – deck area, Effective Significant Wave Height and a real time heave trend curve. The grid of the vessel deck changes colour according to the set wave limits for the crane. Red area indicates unsafe lifting conditions, green area indicates safe lifting conditions and yellow is a warning of approaching unsafe conditions.

Traditional method

The traditional method, using wave buoys, radars or manual observation of the sea state, does not take any further consideration to the following:

  • The accuracy of the estimated / measured Significant Wave Height (H1/3)
  • The variation in wave type and period
  • The variation in downward velocity at different deck positions
  • The variation in shape, stability and loading condition of the vessel
  • The variation in direction of the waves in relation to the vessel heading

By using the DMM all the above mentioned uncertain factors are eradicated. With the DMM system, the Vessel Officer and Crane Operator can make safe decisions based on facts.

 Some typical reference vessels/rigs fitted with ShoreConnection DMM