Load Cells for Offshore Mooring Project
French maritime engineering specialist Iroise Mer used a 50 ton Straightpoint Radiolink plus (RLP) load cell during a refit of a tanker mooring system located 500m off the Corsica coast, recently.
Iroise Mer's job was to update the site, comprising four different mooring lines, complete with anchors, chains and concrete deadweights, and all existing components had to be removed and new ones installed. The RLP was used to measure pre-tension up to 30 ton to check new anchors were properly installed into the seabed.
The RLP was positioned between the anchor line (or chain) and the towing cable on a vessel, attached with two Green Pin shackles. Straightpoint does have a product for measuring tension on lines, the Running Line Dynamometer (or TIMH), specifically built with dockside, marine, offshore, towage and salvage applications in mind.
However, as David Mullard, SP business development manager, explained, “the TIMH wouldn’t have been suitable because anchor chain was being used rather than wire rope. Wire rope can bend, allowing it to pass through the sheaves of the TIMH so that a tension measurement can be calculated. The large dimension chain wouldn’t have allowed the same thing to happen,” he said.
Pierre Recoules, project manager at Iroise Mer, who was aboard the nearby boat, took Readings on a Handheld Plus. He explained that safety was improved, as there was no need to put personnel in the towing line where the load cell was attached. “The buoy is the extremity of the mooring line, where the tanker will be connected. The tug was then connected to the buoy for pre-tensioning. We encounter this kind of work only once or twice a year and when the need arises, utilizing a load cell will add efficiency and safety to any scenario where we need to calculate force on lines, anchors, cables or other maritime equipment.”
The new anchors and chains were manufactured in France before being shipped to Corsica, a mountainous French island that is actually close to the west coast of Italy. The jobsite was off the coast of Solenzara on the island’s east.
Iroise Mer, founded in 2002, has been part of the Thomas Services Maritimes (TSM) group since 2013. Iroise has a fleet of six vessels, ranging from 10m to 41m in length, all of which boast cranes, winches and shallow drafts, suiting them to lifting and towing projects. TSM has a fleet of 20 additional vessels, predominantly tug boats for harbour towing operations.
Two vessels, TSM Molène and TSM Penzer, were used for the Corsica project, which are 21m and 27m in length respectively. Tension was applied via the vessels’ thrusters. Recoules led a 10-person team, who completed the work inside a calendar month.