# Hormuz strait - starting a tanker (ship)

**URL:** <https://boards.straightdope.com/t/hormuz-strait-starting-a-tanker-ship/1029145>\
**Category:** Factual Questions\
**Created:** [April 9, 2026, 10:47am UTC](https://boards.straightdope.com/t/hormuz-strait-starting-a-tanker-ship/1029145 "2026-04-09T10:47:48Z")\
**Posts on this page:** 20\
**Page:** 1

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**Author:** ![Al128](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/al128/32/16541_2.png) [@Al128](https://boards.straightdope.com/u/Al128)\
**Post date:** [April 9, 2026, 10:47am UTC](https://boards.straightdope.com/t/hormuz-strait-starting-a-tanker-ship/1029145/1 "2026-04-09T10:47:48Z")

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Given that the HS will open up again now I was wondering what’s involved in starting those huge engines in tankerships.

The uneducated me thinks the starter motor will be like truck engine. Or so.

Any deeper knowledge here and any discussion of those huge engines welcomed .

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**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\
**Post date:** [April 9, 2026, 10:57am UTC](https://boards.straightdope.com/t/hormuz-strait-starting-a-tanker-ship/1029145/2 "2026-04-09T10:57:59Z")

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They use compressed air to drive the cylinders around till the engine starts

There are large compressors on board filling compressed air tanks for starts and re-starts.

No starter motor as such.

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**Author:** ![bump](https://avatars.discourse-cdn.com/v4/letter/b/7c8e57/32.png) [@bump](https://boards.straightdope.com/u/bump)\
**Post date:** [April 9, 2026, 12:48pm UTC](https://boards.straightdope.com/t/hormuz-strait-starting-a-tanker-ship/1029145/3 "2026-04-09T12:48:50Z")

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And I’d guess smaller diesels to drive the compressors to fill those tanks as well.

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**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\
**Post date:** [April 9, 2026, 12:51pm UTC](https://boards.straightdope.com/t/hormuz-strait-starting-a-tanker-ship/1029145/4 "2026-04-09T12:51:57Z")

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Not too small but yes. Typically three to five large auxiliaries. They also provide electrical power when the main engine isn’t running and during manoeuvres, and are always on standby.

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**Author:** ![md-2000](https://avatars.discourse-cdn.com/v4/letter/m/9d8465/32.png) [@md-2000](https://boards.straightdope.com/u/md-2000)\
**Post date:** [April 9, 2026, 1:57pm UTC](https://boards.straightdope.com/t/hormuz-strait-starting-a-tanker-ship/1029145/5 "2026-04-09T13:57:49Z")

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Another issue I read about - you have ships sitting there waiting that were not intended to be sitting offshore for this length of time. Some were running out of fresh water and the ports really didn’t have the infrstructure to shuttle large quantities of supplies out to anchored ships, or the facilities for fully loaded tankers to re-dock to take on supplies. Not to mention, the month some have been waiting at anchor is about the length they would have been underway, so they may be reaching the end of food supplies too. So apparently there’s a serious logistics problem over and above starting the engines. Also the Gulf states are not keen to have large numbers of third-world crew wandering their cities on shore leave, even if the crew could afford it, so they’ve been stuck on those ships.

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**Author:** ![Al128](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/al128/32/16541_2.png) [@Al128](https://boards.straightdope.com/u/Al128)\
**Post date:** [April 9, 2026, 7:39pm UTC](https://boards.straightdope.com/t/hormuz-strait-starting-a-tanker-ship/1029145/6 "2026-04-09T19:39:39Z")

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yep, for many sailors it must be april 2020 all over again (trapped off-shora due to Covid)

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**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\
**Post date:** [April 9, 2026, 9:38pm UTC](https://boards.straightdope.com/t/hormuz-strait-starting-a-tanker-ship/1029145/7 "2026-04-09T21:38:25Z")

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Or the folks who got trapped on stalled ships when the Container ship MV _Everclear_ (j/k it was really the MV **[Ever Given - Wikipedia](https://en.wikipedia.org/wiki/Ever_Given)**) got jammed sideways in the Suez canal. See **[2021 Suez Canal obstruction - Wikipedia](https://en.wikipedia.org/wiki/2021_Suez_Canal_obstruction)**. Oops.

That grounding only lasted a week, but the backlog took a bunch longer to clear.

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**Author:** ![md-2000](https://avatars.discourse-cdn.com/v4/letter/m/9d8465/32.png) [@md-2000](https://boards.straightdope.com/u/md-2000)\
**Post date:** [April 9, 2026, 10:42pm UTC](https://boards.straightdope.com/t/hormuz-strait-starting-a-tanker-ship/1029145/8 "2026-04-09T22:42:36Z")

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> [@Princhester](#):
>
> Not too small but yes. Typically three to five large auxiliaries. They also provide electrical power when the main engine isn’t running and during manoeuvres, and are always on standby.

I wonder how many weeks of fuel those have, since we’re mentioning supplies that may be running low. Or would they use the same fuel tanks as the main engines?

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**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\
**Post date:** [April 9, 2026, 11:08pm UTC](https://boards.straightdope.com/t/hormuz-strait-starting-a-tanker-ship/1029145/9 "2026-04-09T23:08:41Z")

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The auxiliaries run on diesel. The main engine runs on heavy fuel oil.

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**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\
**Post date:** [April 10, 2026, 12:01am UTC](https://boards.straightdope.com/t/hormuz-strait-starting-a-tanker-ship/1029145/10 "2026-04-10T00:01:17Z")

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… but to (fail to) answer your other question, there is no exact answer. I am more familiar with bulkers than tankers but in my experience very long waits to load or discharge are normal and consequently the vessel would typically be supplied with diesel on the assumption that it may have to wait around for many weeks. Bunkering can be arranged while waiting but load and discharge ports are often not the cheapest place to bunker, so owners will commonly try to avoid needing to bunker at such locations.

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**Author:** ![pullin](https://avatars.discourse-cdn.com/v4/letter/p/c57346/32.png) [@pullin](https://boards.straightdope.com/u/pullin)\
**Post date:** [April 10, 2026, 12:10pm UTC](https://boards.straightdope.com/t/hormuz-strait-starting-a-tanker-ship/1029145/11 "2026-04-10T12:10:55Z")

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Do these ships have watermakers installed? I thought they were common aboard large vessels like these.

When I was working the oil fields, our vessel had a watermaker sufficient to provide drinking water for the crew. We went for about 2 weeks with no resupply (food or water) due to a storm, but could produce enough for drinking and cooking. Showers were forbidden though.

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**Author:** ![Al128](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/al128/32/16541_2.png) [@Al128](https://boards.straightdope.com/u/Al128)\
**Post date:** [April 10, 2026, 12:33pm UTC](https://boards.straightdope.com/t/hormuz-strait-starting-a-tanker-ship/1029145/12 "2026-04-10T12:33:57Z")

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Color me surprised (that this isn’t a standard thing) …

heck, just look what drips out under the hood of florida cars (H2O as A/C condensate) - extracting good amounts of water from 1m^3 of cabin air of a F150 - now multiply that by 10,000 for the space of the bridge/quarters of a tanker. I’d assume there is A/C on those ships …

Also, I understand there are min. crews (\<10 people) on board so you don’t need a lot of drinking water…

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**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\
**Post date:** [April 10, 2026, 12:37pm UTC](https://boards.straightdope.com/t/hormuz-strait-starting-a-tanker-ship/1029145/13 "2026-04-10T12:37:00Z")

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Some of these ships, you read, get abandoned for months, sometimes many months. And they are unseaworthy buckets of rust where nothing works; you probably want to worry about finding some drinking water before spending time fixing the A/C…

> **[The shadowy world of abandoned oil tankers](https://www.bbc.com/news/articles/cddg885344do)**
>
> A growing number of tankers and other commercial vessels are being ditched by their owners.

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**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\
**Post date:** [April 10, 2026, 12:54pm UTC](https://boards.straightdope.com/t/hormuz-strait-starting-a-tanker-ship/1029145/14 "2026-04-10T12:54:11Z")

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That looks like an interesting story. I wonder when BBC went paywall? ☹

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**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\
**Post date:** [April 10, 2026, 12:57pm UTC](https://boards.straightdope.com/t/hormuz-strait-starting-a-tanker-ship/1029145/15 "2026-04-10T12:57:24Z")

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The vessels the subject of this thread are those blockaded by Iran - essentially those serving the US and its allies. They will be well run vessels because you can’t trade to the US or Australia or Western Europe with a rust bucket.

The shadow fleet vessels your article describes are sanction-evading vessels serving Iran’s allies.

There is consequently little if any overlap.

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**Author:** ![pullin](https://avatars.discourse-cdn.com/v4/letter/p/c57346/32.png) [@pullin](https://boards.straightdope.com/u/pullin)\
**Post date:** [April 10, 2026, 1:00pm UTC](https://boards.straightdope.com/t/hormuz-strait-starting-a-tanker-ship/1029145/16 "2026-04-10T13:00:39Z")

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> [@Al128](#):
>
> Also, I understand there are min. crews (\<10 people) on board so you don’t need a lot of drinking water…

Interesting. We had a crew of 340, and the watermakers were huge machines with their own area belowdecks. I don’t know how much they produced daily though. I’m curious how large the aux engines are on a tanker. We had 6 3000hp diesels just for electrical power, so there was plenty for A/C, watermakers, galley, etc. I suspect that tankers might not have a lot of excess electrical capacity for backup devices, but it seems easy enough to supply less than 10 people.

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<div class="post-metadata">

**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\
**Post date:** [April 10, 2026, 1:07pm UTC](https://boards.straightdope.com/t/hormuz-strait-starting-a-tanker-ship/1029145/17 "2026-04-10T13:07:58Z")

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> [@Al128](#):
>
> Also, I understand there are min. crews (\<10 people) on board so you don’t need a lot of drinking water…

Over 20 for a substantial tanker in international trade, as all ships relevant to the OP would be.

Have a look at [Tables 5 & 6 in this document](https://oro.open.ac.uk/40252/1/__userdata_documents2_mg2482_Documents_ORO%20PDFs_Analysis20of%20crewing%20levels.pdf) [second time I’ve posted this cite in two months]

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**Author:** ![andrewm](https://avatars.discourse-cdn.com/v4/letter/a/c57346/32.png) [@andrewm](https://boards.straightdope.com/u/andrewm)\
**Post date:** [April 10, 2026, 1:17pm UTC](https://boards.straightdope.com/t/hormuz-strait-starting-a-tanker-ship/1029145/18 "2026-04-10T13:17:52Z")

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Link doesn’t work. It’s missing a ‘%’ in the middle.

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**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\
**Post date:** [April 10, 2026, 1:23pm UTC](https://boards.straightdope.com/t/hormuz-strait-starting-a-tanker-ship/1029145/19 "2026-04-10T13:23:39Z")

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Hmmmm[, try this](https://oro.open.ac.uk/40252/1/__userdata_documents2_mg2482_Documents_ORO%20PDFs_Analysis%20of%20crewing%20levels.pdf)

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**Author:** ![jnglmassiv](https://avatars.discourse-cdn.com/v4/letter/j/f07891/32.png) [@jnglmassiv](https://boards.straightdope.com/u/jnglmassiv)\
**Post date:** [April 10, 2026, 1:52pm UTC](https://boards.straightdope.com/t/hormuz-strait-starting-a-tanker-ship/1029145/20 "2026-04-10T13:52:45Z")

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> [@pullin](#):
>
> We had a crew of 340, and the watermakers were huge machines with their own area belowdecks. I don’t know how much they produced daily though.

That’s a huge crew, easily needing 1000 gallons a routine day. I wonder if the drilling or pumping ops consume freshwater, too.

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