Navatech was contracted by BibbyOffshore to assist the structural side of the installation of a 75Te caisson for the Maersk Tyra East Platform.

This work included:
• Platform survey (Tyra East) to assess the wire path for the temporary installation winch
• Caisson payload evaluation
• Caisson structural assessment during lifting and transit
• Rigging design for the cross haul between the vessel & platform winches
• Sea-fastening design
• Temporary installation aids design for the caisson including mudmats with friction clamps and buoyancy tanks.

The mudmats were used to protect the caisson coating and to keep the caisson in the correct orientation for lifting onboard the "Olympic Ares".

The caisson takes about 15deg angle when submerge. Hence the bottom mudmat has been equipped with buoyancy tank to reduce the tipping angle to approx 10deg. The mudmats also allows the caisson to slide on the seabed during the landing phase.
Two friction clamps on each mudmats have been designed to be "ROV friendly", see ROV bucket above the stud bolts.

(Photos courtesy Bibby Offshore)

Caisson transportation onshore:

Seafastening onboard the "Olympic Ares":

Lifting phases: