Dozens of private-equity firms appear to be searching for opportunities to penetrate the US tanker market in a bid to cash in on the shale-oil revolution, but they are not the only ones scouting the sector.

Last week, Castleton Commodities of the US made an appearance at the TradeWinds Jones Act Shipping Forum in Manhattan, fuelling speculation that the company may be looking to invest in tonnage tied to the cabotage trade.

Observers