How to Avoid Confusion When Adjusting the Ship’s Time

by | Last updated Nov 24, 2023 | How-to Guide, Seaman's Life | 0 comments

Clock changes are part of a seaman’s life. The first time I experienced adjusting the ship’s time, it was not a big deal actually since I was a day worker.

However, when I heard about the ship’s time being retarded was, well, a bit confusing. How could time be retarded when it only ticks and doesn’t think?

Then I learned that it will be moved backward to comply with the Daylight Saving Time. Perhaps I wasn’t listening well in school, too.

As a deck cadet on a day work schedule, it didn’t bother me much since I only needed to adjust my clock one hour back. Plus it meant more sleeping time or movie time.

But when I joined the ranks of watchkeepers, clock adjustments suddenly became tricky, confusing, and a source of quarrel sometimes!

Why adjust the time?

Everything a ship does is logged. And since the core of every ship is business and regulation, timekeeping is a very important element.

It wouldn’t be a problem if the ship only does business with itself. But since our cargoes are loaded and discharged in different places, we must conform to the time of that place.

Normally, the Navigation Officer, with Master’s advice, is in charge of watching out for these time changes.

Here are a few reasons why we need to adjust the ship’s time.

1. Avoid confusion

Setting the ship’s clock to local time avoids confusion between the ship’s crew and shore personnel.

I work in a tanker ship and when the loading arm is connected, some jettymen ask for the time of connection. This is to synchronize the activities in both parties’ official logs.

Besides, the shore crews know more about the time of tide, the time agents or other visitors arrive, cargo completion, and many others. Having the same time with them helps a lot to avoid miscommunication.

Another thing I experienced was in the shipyard. We have to start working when the yard workers come. The same is true during lunch, coffee breaks, and what time the day ends.

A poster announcement that the ship time will move backwards by 1 hour tonight.
Ship time will move backwards by 1 hour tonight

2. Long voyages

When traveling eastward or westward, you may find your ship adjusting the ship’s time more often. A voyage from India to Mexico will give you 10 hours of incremental retards on your clock.

If done poorly, you may have your 9 a.m. darker than usual on some days. Time adjustments must be done accordingly every 15 degrees of longitude.

3. Daylight Saving Time

In some places, the time is adjusted to conform to what is called Daylight Saving Time or DST.

DST is an internationally recognized practice wherein the clock is turned ahead during summer and backward during winter.

Not all countries practice this and those who do are mostly from the northern hemisphere where the days are longer during summer and shorter in winter.

Europe, North America, Russia, and Australia are just a few places using DST.

Whether your ship anchors or sails in these areas in time for the DST schedule, you may have to adjust your clock accordingly.

4. Documentation

As I mentioned before, ships make money by doing business. When we talk about business, remuneration is based on time.

Thus, ships record everything related to the shipping business from the start to the completion of a certain voyage.

Besides, the vessel’s time log must also correspond with that of the shore crew- agents, surveyors, loading master, etc.

As visitors to their country, adjusting the ship’s time to local time also implies that we are highly cooperative.

Only One Hour? How is this a problem?

Well, one hour wouldn’t be a problem. It’s just one hour and why would someone cry when they lose one hour of their rest period?

Assuming that only one watch, the 12 to 4 watchmen, will take the clock change. When the time is retarded, let’s say at 2:00 am old time, the new time will be 1:00 am.

This means an additional one full hour of work for the 12 to 4 watchmen. The opposite happens when the clock is advanced.

If you have longer voyages and the same watchkeepers take the retard, this could be draining on their part and unfair too.

Thus, this one-hour adjustment is the root of a few qualms.

Solution leading to confusion

The answer?

The time change is divided by the three watchkeepers, each sharing 20 minutes of the advanced or retarded time.

Many approve this one as a fair solution, a just and equal method of conquering the 60-minute burden.

But in practice, it’s a bit confusing.

Some seafarers get discombobulated on what time they’re going to wake up and others in going to watch.

Since they are getting 20 minutes each, they should be 20 minutes earlier or later for work. It happens in a perfect world but in reality, it’s chaos.

This post will dispel all those puzzles so you can be on time on your watch.

A meme relating to two seafarers, one is angry because the other guy is late for his watch due to being confused regarding the time change.
Confused when the ship’s clock is retarded.

Plus/ Minus One Full Hour? Here are some tricks

For day workers, no need to do anything other than set your personal clock- wristwatch, phone, or wall clock to one full hour.

This guide is for watchkeepers and those who want to be in their ranks.

Crossing Multiple Time Zones

By far, this is the easiest way to deal with time changes.

Say your voyage is expected to advance the ship’s time three times before reaching the destination. The best method would be to give 1 hour of rotational advance to each watchkeeper.

If you plan on adding an hour each on Monday, Wednesday, and Saturday during your 7-day voyage, the watchmen could have a piece of those time changes.

Adding one hour on Monday is for the 12 to 4 watch. Adding another hour on Wednesday for the 4 – 8 duty. And another one on Saturday for the 8 to 12 watch.

No crying. No quarreling. And no envy!

Great Sacrifice

Another trick is to get the retards or advances all by yourself.

If your voyage plies on few, same ports only, it may be good to take the retarded time by the single watch keeper.

When the time is advanced, that same watchkeeper should also take it to compensate for his sacrifice.

But this needs total agreement with the others.

Dividing 1 Hour by Three

Another method in dealing with the time change is to divide by one hour (advance or retard) to three for the three groups of watchkeepers.

This would give them 20 minutes each fair and square.

But as we discussed before, applying them is confusing in real life. Thus, we are here to solve it.

Advance by One Hour

Let’s talk about clock advance first.

When we add one hour to the ship’s time, each watchkeeper must work for 20 minutes less time than normal. 

Why? Because we are removing 1 hour from the 24-hour period. Instead of a normal day of 24 hours, advancing 1 hour makes our day 23 hours only!

Imagine this, if at 00:00H the second officer added one hour after he went to watch, it is immediately 01:00H.

But it can be a bit more complicated than that since we’re adding time on a 20-minute incremental basis.

Going back to our watchkeepers, this means that each must perform 3 hours and 40 minutes during the time change.

First and foremost, choose your base time where you can apply the 20-minute increment. Is it gonna be the old time or the new time?

In this case, let’s use the old time as the reference as this is easy to follow.

Tabulated computation for the watchkeeper's schedule when the time on board is advanced by one hour.

20:00H to 00:00 Watch

The 8 to 12-night watch can normally start at 20:00H. The burden lies on the next watch as to what time he must come.

Depending on your agreement, you must wake him up earlier so he can relieve you at 23:40H OLD TIME.

This is because, at that time (23:40H), you will now apply the 20-minute share. With that, you worked 3 hours and 40 minutes only!

00:00 to 04:00 Watch

Since you will advance the time, you must join the 8 to 12 watch 20 minutes earlier.

This means that you must be on the bridge on or before 23:40H using the OLD TIME.

When you enter on your watch at 23:40H, it will be advanced by 20 minutes so there you have it. Midnight!

Now be sure to ring the next watch earlier so they can relieve you at 03:20H OLD TIME.

From 23:40H to 03:20H, you just completed your share of 3 hours and 40 minutes!

04:00 to 08:00 8 Watch

Some watchmen need 30 minutes before they can be ready for watch. Others need 20 while a few need 15 or 10 minutes.

No matter how many minutes you need for preparation, you must be on the Bridge on or before 03:20H OLD TIME!

Take note of how I specified our reference time to avoid confusion.

When you come at 03:20H OLD TIME, it will be 03:40H using the 12 to 4 watch (20 minutes applied from 8 to 12 watch and 12 to 4 watch). 

Hence, if it’s your turn to add the 20-minute share using the new time (03:40H), it will now be 04:00H (03:40H plus 20 minutes).

8 to 12 Watch

Now this is very easy for two reasons.

First, 8 to 12 watch needs breakfast so they usually set their alarms earlier. Or he made some agreements with the Messman or the AB to call him.

Second, before they sleep at the end of their previous watch, they only need to change their personal clocks one hour in advance.

Thus, they already conformed to the new time because when they wake up, the time has already advanced by one hour, syncing their personal clock to the ship’s time!

One Hour Back or Retard

This is just like the former but the opposite. Each watch will have 20 minutes retard instead of advance.

For day workers, this is an hour of extra sleep. But for watchkeepers, this means 20 minutes extra working time.

Why? Because we are retarding 1 hour from the 24-hour period. Instead of a normal day of 24 hours, going 1 hour back makes our day 25 hours!

Imagine this, if at 00:00H we retard the time by one hour, it is still 23:00H the previous day.

So going back to our watchkeepers, this means that each must perform 4 hours and 20 minutes during the time change.

Since the time is moved back, you must add 20 minutes to the OLD TIME which is your REFERENCE TIME. The table below sum’s it but move along to get its best explanation.

Tabulated computation for the watchkeeper's schedule when the time on board is retarded by one hour.

20:00H to 00:00 Watch

Your duty will be extended by 20 minutes. Thus, you will work from 20:00H to 00:20H OLD TIME. Your reliever must arrive 20 minutes after midnight still on OLD TIME.

Here, you have now worked 4 hours and 20 minutes.

00:00H to 04:00 Watch

You have to be on the Bridge on or before 00:20H OLD TIME. By applying your 20-minute share of the retarded hour, your new time will be 00:00H. Spot on!

Then again, make sure your reliever will come at 04:40H OLD TIME.

With that schedule, you will have completed 4 hours and 20 minutes of duty.

04:00 to 08:00 Watch

Your duty will start at 04:40H OLD TIME, UNADJUSTED!

Applying 12 to 4’s share will give you 04:20H NEW TIME. Implementing your 20-minute portion sets your time at 04:00H.

08:00 to 12:00 Watch

Again, the same logic as with clock advances.

Only this time, you can easily adjust your time to the new time and set everything like your usual routine.

So before going to bed the night before, retard your clock by 1 hour and you should be waking up in sync with the ship’s clock the next day.

Golden Rule

Hope this helps alleviate the confusion.

As a golden rule, each watchkeeper must work 20 minutes less if the ship’s time is advanced and 20 minutes more if the ship’s time is retarded.

If you have more questions, hit me with an email. I’m currently in the middle of the Atlantic right now and my next post will be about my message in a bottle.

Or maybe something else.

Stay tuned and

May the winds be in your favor.



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