Ainscough Crane Hire’s Heavy Cranes team has joined forces with Gilpin Demolition and Dorset Council to remove a sunken fishing vessel from Weymouth Harbour.
The boat, called FV Gitte and built in 1982, was a former Danish trawler that was 17.7m in length. It had been moored up in the harbour behind Weymouth Pavilion since being discarded in March 2020.
Harbour staff from Dorset Council had been pumping water from the vessel on a weekly basis to stop it sinking since it was abandoned. In March this year permanent pumps were fitted and monitored daily.
However, this comprehensive program was not enough to stop the vessel sinking at the start of October.
After the sinking, various equipment was put in place in an attempt to mitigate the damage, including 25m absorbent filled seven anchors, smaller booms and seven absorbent nettings bags.
At this point, the Council enlisted Gilpin Demolition to manage the removal and ultimate dismantling of the vessel. Ainscough was appointed by Gilpin to complete the lift from the harbour.
A survey of the vessel had estimated that its weight would be 73t. However, due to uncertainties of how much water could be pumped out before and during the lift, Ainscough planned for a 115t lift.
No exact drawings were available of the vessel and so Ainscough planned where to sling the boat based on a combination of information from the survey and historical details related to other, similar vessels,. This entailed a system within the lifting tackle which allowed the altering of the pitch of the boat as it came out of water.
In order to complete the lift, Ainscough used a LG1550 crane rigged on SLDB configuration with a 42m main boom with 160t main counterweight, 140t tray counterweight and additional 7.5 x 2.2 steel mats. A Liebherr 100t crane was also used for the rigging.
The boat was steadily lifted until it gained weight. At 80t, it was high enough to put pumps in to remove more water. As this weight was lost it was hoisted up to enable the pumping and draining of further water still.
The vessel’s final weight when as much water was removed as possible was 83t.
A 60t air hoist was incorporated into lifting arrangement so as the boat was lifted Ainscough could adjust its level.
The operation entailed a day and a half of rigging and a half day preparing with the divers. The lift itself started at 11am on 12th November and was complete within two hours, with the vessel lifted into the air and onto stands behind the harbour pavilion where it was handed over to Gilpin Demolition.
Patrick Denby, Heavy Cranes contract lift manager at Ainscough Crane Hire, said: “This lift presented a few challenges. The vessel being submerged in the water – combined with there being scant official detail regarding its dimensions – meant we had to factor in a range of uncertainties and plan accordingly.
“Our lift plan was informed by guidance from the Harbour team and the council combined with our own experience in lifting submerged boats. Ultimately, this meant that the lift itself went incredibly smoothly and we were able to complete the operation and handover the vessel to our colleagues at Gilpin Demolition with no complications.”
Ainscough’s team for the operation included Patrick Denby, lift supervisor Dave Hodgson slingers Carl Barton and Sam Drummond, crane operators Rob Perrins and Dave Lamour in addition to Warren Maxwell and Chris Daughtrey.