A "manipulative and angry" woman has been jailed for 18 months after drilling holes in her estranged husband's £75,000 yacht and causing it to sink on Valentine's Day.

Mandy Fleming "lost it" when she saw her husband Adam had bought a new television and other equipment for the vessel, named Double Dragon, while telling her he had no money.

She drilled three holes in the hull of the boat, which was berthed at Brighton Marina, and turned on cooker gas taps turning it into a "bomb", the Old Bailey heard.

Fleming, 47, of Sheerness, Kent, had admitted endangering life by causing criminal damage in 2004, during a hearing last month.

She wept as she was sentenced on Thursday, with judge Richard Hone telling her: "You were a manipulative, angry and troubled individual."

She was told she would have to serve half the sentence, less the 10 weeks she had initially spent in custody.

Fleming had gone to the yacht for a "menage-a-trois" with her then lover, David Brown, and his wife Nemone, the court heard.

After seeing new electrical equipment and some bills for work which had been done on the yacht, she rang her estranged husband, a haulage contractor, and berated him for spending money on the vessel, said Mark Gadsden, prosecuting.

"She returned to the shore and equipped herself with a drill which she took on to the boat and drilled three holes.

"Between them, they were sufficient to cause the boat to sink."

She then turned the cooker gas taps on. The court heard turning on a light would have been enough to blow up the boat.

The slowly sinking vessel was seen the next morning and berthing master Chris Cheyne smashed a porthole to get into the yacht, intending to pump it out.

"He noticed a wedding photograph of the couple in a glass frame had been smashed deliberately," said Gadsden.

"A volatile mixture of propane gas and air had been created and all it would have needed was for someone to turn on an electric light or torch, or respond to a mobile phone or radio, for it to have exploded."

Cheyne told the court: "I had a radio on me and I knew the smallest spark would trigger off an explosion."

Four people on nearby boats had to be evacuated. Damage estimated at £40,000 was caused to the boat.

Police later found an entry in Fleming's diary which read: "Lost it, got drill and sunk boat. Now I am in shit."

The court heard the couple married two years before the incident and the yacht was bought during the marriage. It was her third marriage. They have since divorced.

Oliver Blunt QC, for Fleming, said: "She has little recollection of the gas being turned on. They had all been drinking and were very much the worse for wear."

Fleming had initially been charged with damaging the boat but was later charged, with David Brown and another man, of plotting to kill her husband by hiring a hitman.

But the charges were dropped last month after supergrass Gary Eaton, the chief witness, was discredited.

Earlier this year, his evidence was also excluded from the failed prosecution of three men charged with murdering private detective Daniel Morgan.