[A protester looks through the closed entrance of the Labour ministry during a protest of Greek doctors against planned pension reforms in Athens]Ferries were docked at Greek ports on Wednesday as sailors kicked off their second 48-hour strike this week, adding to a groundswell of public discontent over plans to reform the country's struggling pension system. Prime Minister Alexis Tsipras launched a vocal defence of the plan on Tuesday, saying that the country had no choice but to reform a pension system which had created chronic deficits and would collapse if left unchanged. Greeks, many of whom will see contributions jump to about 20 percent of monthly earnings to prop up the new pension system, have responded angrily to the proposed changes, staging a series of rallies and protests across the country in recent weeks.