The Baltic Exchange’s main sea freight index, which gauges the cost of shipping commodities such as iron ore, cement, grain, coal and fertiliser, fell on Tuesday as rates for bigger vessels dropped. * The overall index, which factors in the average daily earnings of capesize, panamax, supramax and handysize dry bulk transport vessels, fell 75 points or 3.84 percent to 1,876 points. * The Baltic’s capesize index tumbled 270 points or 8.21 percent to 3,017 points. * Average daily earnings for capesizes, which usually transport 150,000 tonne cargoes such as iron ore and coal, were down $1,933 at $29,401 on Tuesday. The earnings have dropped about 17 percent from $35,316 on Jan. 2. * The Baltic’s panamax index slipped 32 points or 1.86 percent to 1,692 points. * Average daily earnings for panamaxes, which usually transport 60,000 to 70,000 tonne cargoes of coal or grains, were down $258 at $13,487. (Reporting by Koustav Samanta in Bangalore, editing by David Evans)