Rates for clean tankers in the Caribbean have dropped by nearly a quarter in the last 10 days, falling below the W300 mark for the first time since last July. London's Baltic Exchange closed Thursday with its assessment of the route pegged at W293 for 30,000 ton cargoes to New York. It put transatlantic 30,000 ton cargoes at W304, 19 percent down on 10 days ago. U.S. brokers said the decline stemmed entirely from the closure of the Atlantic arbitrages for gasoline and gasoil, and that tankers were piling up on the U.S. Atlantic coast with very few cargoes to carry. But brokers in London remained upbeat. "It's not all that bad," said one, adding that 30,000 ton Caribs upcoast cargoes of naphtha were still being fixed at around W350 and other clean cargoes at around W310. Caribbean clean tanker rates peaked in December at over W440 for 30,000 ton cargoes while transatlantic clean tanker rates peaked at the same time at W480. - (Reuters)