In written testimony, the ship's crew said they used flares to hold off the attackers, who sped their skiff toward them firing volleys from automatic weapons and at least one round from a rocket-propelled grenade launcher.
Danish marines who flew over the pirates' skiff in a helicopter said they saw no weapons on board but that the small boat was carrying a ladder with hooks at one end used for boarding ships. The helicopter pilot said there was no doubt that it was an act of piracy.
After the Danish helicopter fired warning shots at the skiff, four of the pirates jumped overboard. The fifth also leapt into the water a short time later. All five were then picked up by a Danish navy boat. They were later handed to Dutch authorities for trial because the Samanyulo was sailing under a Dutch Antilles flag.
Last week, a Somali man pleaded guilty in a New York court to hijacking the US-flagged ship Maersk Alabama on April 8, 2009, and kidnapping its captain. He faces a minimum 27 years in prison. Sentencing was set for October 19.
Besides the US case, Kenya and the Seychelles have been the only countries prosecuting suspected pirates, but Kenya halted its trials, citing the high cost of imprisoning suspects and bringing them to court. Last week, however, Kenya announced it will resume taking piracy suspects from the international fleet for trial.
Kenya has convicted 18 Somalis of piracy since 2007, including eight who were sentenced in March to 20 years imprisonment, and more than 100 others on trial, said Keriako Tobiko, Kenya's director of Public Prosecutions.
In Seychelles, 40 suspected Somali pirates are on trial, but none has yet been convicted, said president's office press secretary Srdjana Janosevic.
Earlier this month, U.N. Secretary General Ban Ki-moon said there were 406 pirate attacks in 2009, 100 more than in 2008. Most were off the coast of East Africa, which saw a sevenfold increase between 2005 and 2009, he said.
Pirates are believed to be holding more than 400 seamen hostage.