The skipper of the Elin Toril had planned to leave at 3pm for the Lofoten Islands, off the coast of Norway, despite the presence of four protesters who had chained themselves to the harpoon gun, the bridge and the crow's nest.
But the whaler was prevented from leaving the upper reaches of the Clyde because seven more Greenpeace supporters manacled themselves to a swing bridge half a mile down river. They are protesting at Norway's unilateral decision to resume commercial whaling next year, despite the current ban on hunting minke whales in the north-east Atlantic.
Greenpeace says the stock of minke whales in the area is depleted and claims that Norway was responsible for killing 100,000 whales in 50 years.
The 65ft (19.8m) Elin Toril came to Stobross Quay to support the Norwegian delegation at this week's International Whaling Commission meeting in Glasgow.
A French proposal for the IWC to make the seas around the Antarctic a whale sanctuary seems unlikely to be put to a vote this week. Japan has been organising a resistance campaign and has the backing of four tiny, fairly poor Caribbean islands, two of which - St Vincent and the Grenadines and St Lucia - have been siding with Japan in the pro-whaling lobby for several years.
But anti-whaling nations and environmental groups have been alarmed by the arrival in Glasgow of delegations from St Kitts and Dominca, two small island states that appear to be supporting Japan. St Kitts has just become a member of the commission, while Dominica rejoined after withdrawing in 1983.
Environmentalists have claimed that the IWC membership fees of the four Caribbean states were being met by Japanese whaling interests, as well as their expenses in sending delegates to Glasgow.
Alan Macnow, whose New York-based public relations company has been retained by the Japanese Whaling Association, said: 'That's sheer nonsense.' The four countries were supporting Japan because the anti-whaling nations which dominate the commission were threatening to broaden its remit to cover small whales and dolphins. The island states hunt these mammals.
The French need a 75 per cent voting majority for the proposal for an Antarctic sanctuary to be turned into a decision. No whaling south of 40 degrees latitude would be permitted, but this is where Japan currently takes 300 minke whales a year in its 'scientific whaling' programme.
Japan, Norway and the four Caribbean states will oppose the sanctuary plan and at least as many other countries are likely to abstain. With only 29 of the 38 IWC member nations attending the Glasgow meeting, the required majority seems unlikely.
Anti-whaling groups are now talking about organising a tourist boycott of the Caribbean islands.
Norway continued to come under fire yesterday over its plans to resume commercial whaling in the north-east Atlantic next year, killing minke whales in defiance of the IWC's four-year moratorium. The minke whales it plans to take are classified as a protected stock.
Fifteen IWC nations, including Britain, expressed their 'deep disappointment' in a statement in Glasgow yesterday and urged Norway to reconsider.