Can you think of a low cost item that if not replaced can cause major damage?

For my research I try to select a spare part that is not critical (not imposed by the regulations), so we do not keep it aboard. The part is infrequently demanded, so the equipment manufacturer does not suggests keeping spare either. For example it could be a sealing ring in a decanter. We appreciate your comments on the subject.

So far with your contribution we have:
A cotter pin, piping, Boat plug, O-Rings, Fuses, tire innertube core/cap, odd shaped cat gaskets flat, tools,zinc cathodic protection.
I would appreciate it if you answer my questionnaire (that is if you have not done it already). We are con ducting research aiming to explore the potential of 3D Printing Spare Parts for the Maritime Industry.

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A horseshoe nail.


I was inspired from the Chinese proverb, but I would like to apply it in shipping.

Maybe I don’t understand your question but it seems analogous to an arbitrage situation. As soon as it’s discovered it is exploited and ceases to exist.

For example it’s like asking what items does the company purchase that can be obtained at lower cost elsewhere. That’s what the purchasing department does, looking for lowest cost. As soon as they learn of the lower cost they switch suppliers.

Likewise if the technical department discovered an item not in inventory that should be, that item will be added to inventory and purchased.

The question amounts to should a spare be carried on a part that may never or likely never fail.
Many years ago I had one of the front air bag collision sensors go bad on my car. When I went to the dealer to get a replacement I was told they didn’t have one as they never fail. Lucky me I thought. The dealer had to order the part. Should they have in inventory something that may never, or rarely get used?

When I worked in Alaska a while back we had a reefer unit fail. The trip was during Christmas and the long time chief had taken a trip off. The relief chief was good but first trip.

The relief told me the part that failed was a small inexpensive part, control unit (?) of some kind that was prone to failure. After an intense search the chief said there was no spare on board. I told him I know the chief and that part has got to be on board.

Sure enough, the relief chief made another search and found a spare.

Good thing as the other option was to unload the full reefer unit ashore, by crew, by hand.

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When reefer boxes with scroll compressors began to appear we were told we didn’t needed to have a spare compressor onboard because the failure rate was so low. They had a 10 year warranty or something like that. That didn’t help us on the way to Guam when one of those nice new scroll compressors failed internally. What works in the trucking industry where parts or repairs are just down the road doesn’t always work in the maritime industry. All the ships got spare scroll compressors soon after. Admittedly they rarely failed but the failure rate was not zero.

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Here are the boxes. Older units I think.

Here’s the regular chief:



There’s a catch-22 in your question. Anything that can cause major damage unless replaced when worn out should be identified as a consumable by the manufacturer, and any minor component that causes a sudden and catastrophic failure is really just a design flaw. There may be some components that will cause expensive long term damage through continued operation, but I can only think of esoteric examples (think gyro vacuum pump) that wouldn’t be touched by shipboard personnel in any case.

This could lead to an interesting discussion on the inadvertent introduction of single points of failure in otherwise robust systems. I once had an old Furuno GPS receiver that decided to go senile and start emitting a strong interference signal at random intervals, knocking out all 5 redundant GPS receivers at once. I initially put it down to malicious action by hostile fishermen, and only managed to isolate the problem after it had persisted for several months.

I also once had an outdoor autopilot remote control that suffered water ingress, which caused it to close the starboard rudder circuit even though the autopilot was switched off. Given the open center hydraulic system controlling both propeller pitch and rudder angle, this put the rudder hard to starboard and prevented me from going astern. It happened as I was right on the edge of my maneuvering envelope in a crowded marina full of shiny fiberglass, so the outcome was rather expensive. I suppose you could call that major damage…


Thank you for your responses.

We are conducting research aiming to explore the potential of 3D Printing Spare Parts for the Maritime Industry. I started a topic 3D Printing Spare Parts Questionnaire for academic research, trying to get the opinion of people aboard a vessel and land office using a questionnaire. We would appreciate if you find the time to participate. I came back with the above question since I need responses from the people that know the job.

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A cotter pin.


It all depends how many reefers you have onboard. In my experience with more than 600 onboard you will have 2 or 3 failures. We carried spare compressors for the three most common makes as well as two electricians.
The time spent repairing containers was charged out to the charterers. The repairs to reefer containers was always treated as urgent due to FDA regulations and the presence of internal logging devices.

No, it doesn’t work like that. A good shipowner employs good crew that can solve any problem. Bad shipowners/pirates employ shit and take any money and run when things go wrong. Unfortunately many underwriters do not see the difference.

Now you’re just trolling. Your statement is so blatantly false that I refuse to believe you’re being serious.


If I had to pick a low cost item that would/can cause major damage I would go with aux engine fuel piping. I’ve seen them fail from vibration, chafing, poor installation. Failure of any fuel piping can cause a fire in a worst case scenario.

Vibration and chafing damage occurs over a long period of time so it would qualify as an “Infrequent” failure. Especially since engineers making good rounds on machinery should be able to catch some of these failures long before they occur.

It’s been a while since I have encountered a sealing ring on a decanter; one only decanted Port and only the Master had access to that.
Ship owners will not put non-critical items onboard a ship because they are not required.
Most of them won’t put critical spares on because they cost money; anybody on here ever sailed with a spare radar scanner? Anti-heeling pump? Cook?

An extra deckhand? Or maybe a spare cook.


Sorry, misread that, thought you said extra dickhead.
Always got far too many of those.

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cotter pin, another case