Fred Pickhardt sr loading bananas

Loading bananas on the SS Junior in the 1950s, image by Fred Pickhardt, Sr.

Years ago if you wanted to import bananas you had two choices. You could pick the bananas when they were still green and un-ripened so they would arrive a week later by ship in a semi-yellowed state but still tasted un-ripened. Your second choice would be to pick them at the peak of ripeness and have them delivered soft and near rotting. Refrigeration helped but you still could not get your product to the consumer at its peak flavor.

Someone discovered that the ripening process needed oxygen for it to take place. If you somehow removed the oxygen the bananas could be picked when ripe and shipped in a compartment where the oxygen was removed. The bananas would not ripen much more and would be delivered at their best flavor.

Loading Bananas. Photo By Tom Guldner

Loading Bananas. Photo By Tom Guldner

This is done today on container ships and break-bulk carriers that carry produce. The usual manner the oxygen is removed from the cargo hold is by the introduction of nitrogen or other inerting gas. An inerting gas simply pushes the oxygen out of an area and then takes its place. Actually the inerting gasses are usually non-toxic in themselves however, the lack of oxygen will kill anyone who enters the area without an SCBA.

Aboard ship there are many areas that have similar hidden dangers of oxygen deficiency which some crew members may be unaware. I think that we all would have serious doubts about entering a newly emptied cargo tank aboard an eight hundred foot gasoline tanker. However, would you also be concerned about entering the chain locker in the bow of this same vessel where only the anchor chain is stored? After all, what kind of a danger could all that nonflammable chain present?

What happens to the outside of the metal chain as it sits in the damp chain locker?

The metal will start rusting. We all remember our training from your Basic and Advanced Firefighting that rusting is a form of oxidation. And oxidation is a burning which consumes oxygen. The oxygen acts with the wet iron or steel and a pyrolysis reaction takes place. This “slow burning” gives off some heat but the metals mass and the surrounding atmosphere dissipate most of that. Our problem arises in the fact that this oxidation is using up the available oxygen that we need to survive. If the compartment in question has no inlet and outlet to allow a circulation of fresh air, we can have an oxygen deficient atmosphere.

rusty ship ballast tank

Rust in ballast tank. Photo By Tom Guldner

Other areas aboard ship which may contain dangerous levels of gasses or reduced oxygen are the ballast tanks (photo left) and other areas within the hull. These areas are generally sealed and not normally occupied. Accumulations of water, sewerage, and cargo leakage may cause a hazardous atmosphere of either toxic gasses or a lack of oxygen.

Normal air contains twenty one percent (21%) oxygen. As this level is decreased, the danger to anyone entering that space increases. It becomes a hazard when the level drops below 19.5%. The progression is as follows:


19.5% Minimum acceptable oxygen level.
15 – 19% Respiration increases. Poor judgment.
12-14% Decreased ability to work strenuously. Impair coordination.
10-12% Respiration increases. Lips blue
8-10% Mental failure. Fainting. Nausea Unconsciousness. Vomiting.
6-8% 8 minutes – fatal, 6 minutes – 50% fatal, 4-5 minutes – possible recovery.
4-6% Coma in 40 seconds. Death


A response to a fire or emergency aboard ship should mandate the inclusion of oxygen meters as well as gas meters in your tool list. Any area aboard ship that is not normally occupied or entered should be considered suspicious.

Most vessels are made of steel. All of these metal surfaces are subject to the oxidation of rusting that we previously discussed. (Just ask the ships deck hands who are constantly kept busy chipping and painting the rusted areas.) Air samples must be taken at all levels of the compartment prior to entry. If you do not have the proper sampling equipment ask a ships officer if they have these meters.

Generally all ships, but especially tankers, will have these meters on board. Regardless of whether the meters are available or not, ONLY QUALIFIED, CONFINED SPACE CERTIFIED personnel should ever enter any space considered a confined space. If you are in doubt as to whether an area is a confined space then…..


My training programs address all of the dangers, which can be encountered at a ship fire or an emergency during your watch. Gas inerting, Oxygen Deficient Atmospheres (in addition to the one discussed here), explosive atmospheres, entrapment dangers, electrical dangers (440 – 880v), and the list goes on. Placing your crew into fire and emergency situations without proper indoctrination and training is unsafe.

Join Tom at the International Work Boat Show in New Orleans on October 10, 2013. Tom will make his presentation from 11 AM to 12 Noon on work boats and Liquefied Natural Gas (LNG). Or you can just stop by to say hello.

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  • Jeremy Irons

    Very good article Lieutenant!

    • Tom Guldner

      Hi Jeremy,
      I’m glag you enjoyed it and thanks for taking the time to let me know.

    • Tom Guldner

      Hi Arne,

      Thanks for your comments. Was that on a ship with refrigeration?

      I remember ships arriving in New York delivering green stalks of bananas in the late 60s and early 70s.

      Were you ever involved in the nitrogen modified atmosphere later on?

  • Charles

    Interesting article – but images don’t seem to appear….

    • Tom Guldner

      Hi Charles,

      I don’t know what happened to the photos. I had supplied one of a chain locker and another of a rusted ballast tank.
      But I guess you got the idea anyway.

    • Ted K.

      Re : Chain locker photo
      Here’s a replacement as part of a podcast.

      The Case Of The Rusty Assassin

      NB – Jump to the image by searching for [ Inside the anchor chain locker ].

    • Ted K.

      Re : Ballast tank photo
      Here’s one that’s on Flickr.

      Ballast Tank 6 Port M/T Brillante Virtuoso

      • Tom Guldner

        Hi Ted,

        Thank you but there are copyrite concerns.

        • Ted K.

          I’m not suggesting you grab their images. I posted those links so that readers could quickly jump to that page and see a reasonable substitute for what got lost along the way. I hope my selections from my image searches meet with your approval.

          By the way, your article seemed somewhat hypothetical at first. Then, when I looked for a chain locker image, I came across a documented case of three (3) fatalities. That drove your point home rather firmly.

        • Ted K.

          P.S. This is one of those ambiguous cases where one’s comments are both to a top-level comment (Charles) and a response of sorts to a previous secondary comment (Tom Guldner). Note how my fourth-level comment is boxed (if it continues what I’m seeing as I type these words) while my second-level comments are banded.

          • John Konrad

            Hi Ted,

            No comments have been banned, please try posting them again.

            -JAK, gCaptain Admin

          • Ted K.

            @ John Konrad
            My reference to “boxed” did NOT mean “banned” or “binned” (Brit.Eng.). It was a reference to the white / gray backgrounds on the comments that can form a frame when the comments are deep enough. Thanks for looking in.

  • Philip Brown

    Thank you very much.

    • Tom Guldner

      Hi Phil,

      Thanks for taking the time to let me know you enjoyed it.

  • Blanca

    very interesting, who would know.

    • Tom Guldner

      Thank you for that link but there is no web-site to go to for me to determine ownership and copyright

  • http://wwwminesrescuemarine Captain Michael Lloyd

    very good to highlight once again the dangers of cargo related gases and the dangers of the enclosed space problem. Here at MRM we have been studying and writing on the Marine related enclosed space problem for three years now and are, together with the Nautical Institute in London holding an Enclosed Space Seminar on the 11th September at the North west Kent marine college during the London marine week. We are the largest enclosed space rescue and enclosed space consultancy in the world and yet we have a problem getting the dangers across, not to the seamen, but to the top management.
    You mention that only qualified enclosed space crew should go into enclosed spaces. The problem is that there are none, at least not on international shipping and that includes all European flag. The IMO does not require training in enclosed spaces or the specialist equipment needed for rescue. That then leaves it up to the ship managers to decide. here we come to the real problem. The marine industry does not have a safety culture. It has a legislative culture and the marine legislation on safety is light years behind that of the shore. Culture is like a river, It flows from the top and the higher it starts the faster it flows. One safety poster in the board room is worth 50 on the ship. Anyway good article, we need lots more like it! Do you know that 10 reported seamen have died at sea in these spaces in the last several months. That leaves the many, many more unreported ones!


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