The cost to ship Middle East crude oil to Asia, the world's busiest route for supertankers, rose for a fourth day, rounding out the first weekly increase in four. Charter rates for very large crude carriers, each able to haul 2 million barrels, on the benchmark Saudi Arabia-to-Japan voyage climbed 0.8 percent to 46.85 Worldscale points, according to the Baltic Exchange in London. Rates climbed 2 percent this week and reached a two-week high today. They dropped 8.5 percent in the three weeks before this week. "It seems the better rate is adding to a small amount of better sentiment in the market, though in today's tough environment, better means half a point at a time," Ben Goggin, a freight-derivatives broker at SSY Futures Ltd. in London, said. Daily rental income, which varies with changes in fuel costs, strengthened to minus $137, according to the exchange. Returns stayed negative for a fifth session in a row, meaning tanker owners are paying part of charterers' costs. The price of ship fuel, or bunkers, rose 26 percent this year to $641.67 a metric ton, according to data compiled by Bloomberg from 25 ports worldwide. Worldscale points are a percentage of a nominal rate, or flat rate, for more than 320,000 specific routes. Flat rates for every voyage, quoted in US dollars a ton, are revised annually by the Worldscale Association in London to reflect changing fuel costs, port tariffs and exchange rates. The Baltic Dirty Tanker Index, an overall measure of shipping crude that includes vessels smaller than VLCCs, declined 0.4 percent to 689, according to the exchange.