The Baltic Dry Index is plunging, but apparently it's a temporary thing, so now might be the time to climb aboard.

The index, which measures the cost of hauling freight across the oceans, has fallen 12% since the start of this week alone, and as a consequence, shipping stocks are getting hammered.

Click here for larger image.

Navios Maritime ( NM - Get Report), Eagle Bulk ( EGLE - Get Report), Genco Shipping & Trading ( GNK - Get Report) and DryShips ( DRYS) are down between 12% and 20% in the same time.

But that's actually the good news.

This phenomenon seems to be a repeat of what happened to the dry-bulk shippers between November and January when iron ore negotiations between the Chinese steelmakers and Brazilian/Australian iron ore producers meant large freight vessels were left idling and freight rates really tanked.

That was a temporary event, and once the ore started shipping again in late January freight rates climbed and buoyed the shipping stocks.

TheStreet.com highlighted this move back in late January (click to watch the video: Freight Stocks Good for the Long Haul). Those who bought at that point would have made out handsomely, right up until a few days ago.

What we are seeing now is likely a repeat event, and it means there is a chance for those who missed the initial run-up to jump in, according to Natasha Boyden, managing director at Cantor Fitzgerald in New York.

Boyden says the Chinese have decided to draw down on their stockpiles of iron ore, around 78 million tons, instead on importing additional material. But those inventories are projected to last only about three to four weeks after which ships will be needed to haul in more, the result of which will mean a rise in freight rates.

"It's a great buying opportunity," Boyden says.