(Bloomberg) — Shipowners doubled spending on second-hand coal and iron-ore carriers in the first quarter as freight rates soared, broker Allied Shipbroking Inc. said.Companies spent $5.6 billion buying 266 vessels, compared with $2.9 billion on 184 ships a year earlier, Piraeus, Greece- based Allied Shipbroking said today in an e-mailed report.

Buying second-hand carriers allows owners to tap rising ship-hire rates immediately rather than waiting up to four years for a vessel to be built. Second-hand ships that haul 170,000 ton cargoes, which cost $55 million, are earning enough to pay for themselves within two years, based on current rental prices.

Profit from dry-bulk shipping “automatically makes it very attractive for investors,” Allied Shipbroking said in the report. Shipowners “don’t even care paying a little premium for their new asset. No-one can predict or suggest what a bulk carrier will cost in a month or even a week,” it said.

Freight rates for shipping commodities have more than doubled in the past year on surging demand for raw materials from emerging nations including China. An Indian tax on iron ore exports also prompted at least 10 Chinese steelmakers to buy in supplies from Brazil and South Africa, increasing voyage lengths and cutting vessel supply.

The London-based Baltic Exchange’s Dry Index, a measure of costs for a range of vessel sizes, was at 5,417 yesterday, up from 2,508 a year ago.

Companies in Greece, the largest ship-operating nation, were the biggest buyers of commodity-carrying vessels in the quarter, spending $2.9 billion on 70 ships, Allied Shipbroking said.

The largest commodity carriers, called capesize ships, currently make more than $92,000 a day, according benchmark shipping rates from the Baltic Exchange. With second-hand prices for such carriers at $55 million, the vessels can pay for themselves in 592 days, excluding interest charges.

Spending on all types of second-hand ships, including crude and refined oil tankers, climbed 6 percent to $9.31 billion, from $8.81 billion last year. Greeks accounted for just under one-third of the total.