Now Mr Hof has told The National that scrapping the ship was "indeed a possibility".
During his visit, which included trips to Hodeidah port and Ras Issa, a vital document on the FSO Safer was signed.
The Safer is a floating storage and offloading unit moored at Ras Issa and connected to a crude oil pipeline in Marib.
The three-party agreement involved UN humanitarian co-ordinator David Gressly, Ibrahim Al Seraji, who heads the Houthi Safer committee, and the Fahem Group wheat importer, which has a vested interest in keeping Yemen’s waters safe from a maritime disaster.
“If you compare the cost to an oil spill and clean-up costs, the operation described in the MOU is cheap. The clean-up has been estimated at up to $20 billion,” said Mr Hof.
The deal is contingent on the provision of donor funds for a ship-to-ship transfer of the 1.1 million barrels of crude oil on board and pay for a replacement vessel to the Safer.
Despite this, the agreement is considered the most significant step in ending the Safer’s threat. It comes after numerous attempts by the UN to convince the Houthis to allow a technical team to inspect the deteriorating vessel had failed.
The Safer is known as a “ticking time-bomb”. With gases gathering in its chambers and the severity of its physical deterioration unclear, an explosion or oil spill would affect fisheries and hundreds of thousands if not millions of lives in Yemen and its surrounding areas.
“We don’t have a final budget but we’re running into tens of millions of dollars for the operation involving the ship-to-ship transfer. It’s still a lot of money,” he said.
He said the agreement does not guarantee an outcome.
“Nothing is agreed until everything is agreed," he said. "The project can only be executed if enough funds are raised depending on the final budget. Then there has to be a final technical plan, which will hopefully come out this week, and after that project documents need to be drawn up.”
The documents will include details about the technical side of the operation, which involves finding a replacement ship and pumping the oil from the FSO Safer without any leaks and as safely as possible.
“This could take weeks,” he said.
The agreement also does not cover what would happen to the 1.1 million barrels of oil, or the Safer itself.
“Scrapping the ship is indeed a possibility,” Mr Hof said.
“They could tow away the Safer and sell the scrap metal which could value at a sizeable amount.”
This portion would come at the very end of the operation, Mr Hof said.
Although experts have been warning for five years about the dangers of the FSO Safer, Mr Hof believes that now, “all parties” have finally realised the sense of urgency.
Hashim Ahmed Ismail, acting president of the Houthi Economic Committee and Houthi Governor of Central Bank in Sanaa, said at a press conference on Thursday the Dutch had provided an important "push" for the deal to be signed.