The Chilean navy and marine scientists will try again next week to find Latin America's first submarine - a manually operated steel tube that sank off the coast of Chile 140 years ago.
A first attempt to locate the "Flach," designed in the 1860s by German immigrant Karl Flach, failed in December.
"Five days at sea were not enough," the organisers of the search
said in statement.
This time, scientists and sailors will spend twice as long at sea with better resources. Sebastian Pinera, a Chilean billionaire who narrowly lost Chile's 2005 presidential election, is helping finance the project.
"The search for the Flach has become a debt which we owe our naval history and which must be paid," said the organisers.
They described the submarine as the first in Latin America and only the fifth in the world to make a successful underwater voyage.
Flach built his vessel at the request of the Chilean government to foil Spain's ambitions in the region. It made several successful test voyages in 1866.
But on May 3 of that year, it sank in the Bay of Valparaiso, 140km west of the capital Santiago. The crew - two Chileans, two Frenchmen and seven Germans, including Flach and his 15-year-old son - all died.
Three days later, the crew of a British frigate located the vessel and tried to raise it. But it was stuck fast in thick mud, some 50 metres (165 feet) below the surface.
Since then, no one has seen it.
The search team identified an area measuring roughly two square miles (5 square km) where they think the vessel lies. They checked 20% of it in December and will start to search the remainder next Wednesday.
Topped by two cannons and an entry hatch, the Flach relied on manpower to move. Crewmembers had to turn handles at the back of the vessel to power the propellers.
Before its launch, only the United States and a handful of European nations had successfully tested submarines.
"There's a high probability we'll find it," Pedro Pujante, a Spanish marine scientist involved in the project, told Reuters.