Given the rising tension in the Strait of Hormuz, and the mysterious spate of seemingly random attacks on tankers that some have blamed on Iran, it's no surprise that more captains transporting shipments of crude and LNG through one of the busiest corridors for the global energy trade feel the need to keep a low profile, according to Bloomberg.

Which is apparently why more ships are turning off their transponders - "going dark", in industry jargon - a technique that is typically used by smugglers and those hoping to avoid American sanctions.

But this time, ships are going dark mostly as a precaution. Following a buildup of military personnel in the region, most carriers fear the prospects of open war between Iran and a coalition of the Americans and the Saudis, or at the very least, more sporadic attacks on vessels that are still simply trying to scratch out a living.

In at least one way, the fact that ships are "going dark" is ironic: Because Iranian ships pioneered the technique while trying to bypass the American sanctions regime.

Copying from Iran's own playbook, at least 20 ships turned off their transponders while passing through the strait this month, tanker-tracking data compiled by Bloomberg show. Others appear to have slightly altered their routes once inside the Persian Gulf, sailing closer than usual to Saudi Arabia's coast en route to ports in Kuwait or Iraq.

Some ships are also trying out new routes that involve spending less time, or no time, in Iran's territorial waters.

Before the latest increase in tensions with Iran, ships were more consistent about signaling their positions as they passed through a waterway that handles a third of seaborne petroleum. Once inside the Gulf, shipping routes took them fairly close to the Iranian coast, skirting the offshore South Pars/North gas field shared by Iran and Qatar. Most still do, but a growing number appear to be trying something new.

It's little surprise that ships are doing everything possible to minimize risk. The Gulf region has witnessed a spate of vessel attacks, tanker seizures and drone shoot-downs since May, all against the backdrop of U.S. sanctions aimed at crippling Iran. War-risk insurance soared for tanker owners seeking to load cargoes in the region.