The vessel – Normandy Trader – which is owned by the Jersey Oyster Company, has been used by the department and Blandin Plant Hire on low tides during recent weeks to clear the seaweed from the most popular areas of the beach.
The landing-craft beaches at Beaumont, where sea lettuce, removed from along the shoreline, is loaded into the vessel.
It is then taken out to a designated dumping area three miles off the south coast, where its cargo is jettisoned.
Martin Gautier, assistant director of technical services at Infrastructure, said: 'So far the trials carried out have gone very well from both the loading of the landing craft on the beach and the disposal of the material in the designated area three to four miles to the south of St Aubin's Bay.'
Mr Gautier says it was costing around £2,400 per day to cover the cost of removing the sea lettuce from the sand, loading the Normandy Trader and dumping it.
He said: 'Dumping at sea will inevitably cost more than taking it to the low-water mark. At this stage the process is being refined and as a result costs are reducing and conditions can vary day to day.'
The trials are seeing about 70 to 80 tonnes of seaweed removed each day between First Tower and La Haule slip.
He said: 'Some trailer loads have still had to be deposited at the low-water mark when the vessel has been loaded to its capacity. As more experience has been gained changes to the loading method have been made to improve efficiency'
Infrastructure are using a drone to monitor how the sea lettuce disperses when it is dumped at sea.