What’s it like to sail a huge cargo ship loaded with thousands of tons of grain out of port from a war-torn nation into mine-infested waters?

That question became relevant with the launch this week of an innovative scheme to allow grain shipments to be exported from Ukrainian ports. Already, the prospects of food scarcity and political unrest, particularly in hungry nations in North Africa and the Middle East, have eased somewhat. But the maritime procedures are far from settled, and for the first few ships sailing outbound, the challenges are daunting.

Will the Ukrainians be able to export a significant amount of the more than 20 million tons of grain straining their storage facilities?

Consider the frightening situation faced by masters of merchant ships like the Sierra Leone-flagged Razoni, which on Monday sailed out of Odesa headed for Lebanon with 27,000 tons of corn. Often, the first inkling of mines in the water is, unfortunately, an explosion. As the master of the Razoni got underway from port, he was no doubt on the bridge moving from side to side, peering anxiously over both the port and starboard bridge wings.

I’ve sailed through minefields, and it is a white-knuckle ride for even the most experienced of mariners. In the 1980s, the U.S. Navy faced Iranian efforts to close the Strait of Hormuz as a part of the so-called Tanker War between the Arab nations and Tehran. In April 1988, the guided-missile frigate Samuel B. Roberts struck a mine and was almost sunk, saved by heroic damage control on the part of her highly trained crew.

Over the course of the Gulf mission, the Navy had a number of other vessels strike floating mines, including the Princeton, a high-end Aegis cruiser, in early 1991.

In the Navy, we pay a lot of attention to mines. Most are tethered to the bottom of the sea, and their positions are carefully marked by the nation laying them, so its ships can transit through safe corridors.

Minefields can be used defensively (as Ukraine is doing to discourage the Russian Black Sea Fleet from attempting an amphibious assault on Odesa) or offensively — as the Iranians did in the Tanker War, putting floating mines in regional waters and propelling them toward US or allied ships.

Mines can detonate in two ways: direct metal-on-metal hull contact on a trigger mechanism on the surface of the mine; or from an acoustic or seismic response by the mine’s arming system to the ship’s engines or the water pressure from its hull passing on the surface.

On both Navy warships and merchant vessels, the first and best defense is good intelligence. The Razoni was escorted by a Ukrainian vessel that would have had exact locations of the mines Ukraine’s navy had laid.

Despite all the advanced technology ships have today, a second key element in avoiding a mine strike is standing a taut visual watch. Having lookouts stationed far forward in the ship and on both sides is critical. For a merchant vessel with a very small crew, that means all hands on deck, using binoculars to constantly sweep the horizon for any unidentified floating objects.

Ideally, one sails through corridors that are not just clearly marked on charts, but also have been verified by a minesweeping vessel. The U.S. operates very capable minesweeping ships that can clear such lanes or confirm they have already been cleared. And the North Atlantic Treaty Organization has a standing minesweeping force that consistently trains and exercises as a team. In 2021, the UK agreed to provide the Ukrainian navy with two such ships, but the war interrupted that plan.

Another safety measure is using overhead sensors that can detect the mines, usually done by helicopters operating either from ashore or the vessel itself, although today unmanned drones may do the job. Most merchants have a limited flight-deck capacity, but using a small helicopter or a drone with the first set of vessels transiting out makes sense.

But all the precautions imaginable are hardly perfect. If the crew sights a mine in the water ahead, the dread sets in: You are operating in an uncleared minefield. The best solution is to try to simply “back down,” like putting a car in reverse, and creeping at the slowest stable speed to exit the area.

It is also possible to detonate or disable a mine using .50-caliber machine guns from the deck or a helicopter, but that is not an option for merchant ships like Razoni. Having Ukrainian or NATO warships within helicopter range would make sense — Romania, Bulgaria and Turkey all have capable navies.

These unfamiliar procedures will be going through the mind of any merchant ship’s master, as his knuckles go white squeezing the bridge railings.

Perhaps some of these precautionary procedures will be tested in the days ahead, organized by the Joint Coordination Centre established under United Nations authority by Turkey, Russia and Ukraine. Every vessel attempting to clear the three Ukrainian ports overseen by this joint effort — Odesa, Chornomorsk and Yuzhny — will be inspected and monitored in transit.

There are roughly 80 vessels awaiting passage out of Odesa, many of which need seasoned mariners who have departed the war zone. The entire coast remains on the high-risk list maintained by Lloyd’s of London Ltd.

Russian President Vladimir Putin has agreed to this export plan under duress, fearing that if he does not compromise on releasing the grain, NATO will simply do it by force, escorting the shipments with warships. He may try to subvert the scheme through a “false flag” operation he can blame on Ukraine or some other covert means. For now, the Western allies should do what they can to support the brave civilian mariners who are sailing into harm’s way.

James Stavridis is a Bloomberg Opinion columnist. A retired U.S. Navy admiral, former supreme allied commander of NATO, and dean emeritus of the Fletcher School of Law and Diplomacy at Tufts University, he is vice chairman of global affairs at the Carlyle Group. He is the author most recently of “To Risk It All: Nine Conflicts and the Crucible of Decision.”