Adding to their fury is news their monarch, King Tupou V, has left the country on an extended Scottish holiday despite being aware the tragedy had occurred.
The latest statistics suggest 119 people were on board the Princess Ashika when she went down 86km from the capital shortly before midnight on Wednesday.
In his distress call, the captain gave his co-ordinates, saying: "We are going to sink in this position."
Rescuers saved 53 people and found the bodies of two others - an unidentified Tongan woman and Briton Daniel Macmillan, who had been living in New Zealand.
Hopes are fading for the remaining 64 passengers, more than half of whom were women and children who were sleeping on lower decks indoors when the boat became unbalanced and rolled.
Veteran democracy MP 'Akilisi Pohiva said people were "extremely angry" as they had tried to stop the monarchy-ruled government from buying the ancient boat.
Its refusal to listen, and the lack of proper government accountability, was triggering increasing tensions "not unlike what we've seen here before".
People were gathering outside the offices of the government-owned Shipping Company of Polynesia, which bought the boat from Fiji two months ago as a stop gap measure before a new vessel was launched in 2011.
"People are extremely angry, everybody knew this ship was going to sink," Mr Pohiva said.
"It was an old ship, it was only good for scrap.
"I have been to the marine department and spoken to their people, and they say it was not licensed and it should not have been operating."
It is hoped the tragedy, coupled with the king's untimely departure and the prime minister's absence for the Pacific Islands Forum in Cairns, does not spark another riot such as the one seen in November 2006.
Most of Nuku'alofa's town centre was looted and razed by demonstrators to protest the royal family's stranglehold on Tonga's governance and economy.
A repeat would be a major setback for the country, which has made several steps towards a more open democratic system in the past year and hopes to hold its first citizen-focused elections in 2010.
Mr Pohiva's view is supported by leading Tongan journalist Pesi Fonua, who said locals had a "bad feeling" about the boat.
They had not wanted to travel on it but had no choice as air travel was too expensive.
Brian Heagney, who runs a dive shop in Nuku'alofa, told a news website that "the mood in the entire kingdom is one of anger".
"Particularly at the shipping company because (people think) the boat is not up to standard and they sailed it anyway," he said.
"Very large crowds have camped outside the offices basically baying for blood."
Information was being passed on "painfully slow", and many people were still not aware whether their family members were alive or dead.
