Sailing tide times maths challenge

Quick answer

By understanding tide times, you can plan when to go sailing to make the most of the water movement and ensure safety on the water.

Learning outcome

By the end of this page, you will be able to read tide times on a chart and work out how long you have to sail before the tide changes.

• You can tell the time when high tide and low tide happen
• You can calculate how much time passes between two tide times
• You can plan your sailing trip using tide times
• You can understand why tide times matter for sailing

Why this matters

When you sail, the tide (the movement of water) changes the way the water flows. Sailing is more fun and safe when you sail with the tide. If you sail against the tide, it's harder and more tiring. Tide times help you plan when to go sailing so you can use the water's flow to your advantage. This maths helps you be a better sailor and understand the world around you.

How it works

Every day, the tide goes up and down. This happens because of the pull of the moon and the sun. The tide has two main times each day:

1. High tide – When the water level is highest
2. Low tide – When the water level is lowest

Between high and low tides, the water level changes gradually. Tide times are shown on a chart with times like 08:30 or 14:15. These are written in 24-hour format, which means:

• 08:30 = 8:30 in the morning
• 14:15 = 2:15 in the afternoon

To work out how long you have between tides, you:

1. Find the time of the next high or low tide
2. Find the time you want to start sailing
3. Subtract the start time from the tide time

Examples you can see

Let's imagine you are going sailing in a small boat. Here is a simple tide chart:

If you want to start sailing at 10:00, you need to know:

• When the next high tide is (13:00)
• How long you have to sail before the tide changes

Let's work this out:

1. Next high tide is at 13:00
2. You start at 10:00
3. 13:00 – 10:00 = 3 hours

You have 3 hours to sail before the tide changes to low tide.

Another example:

You want to sail at 15:00 (3:00 in the afternoon). What time is the next tide?

1. Next tide is low tide at 19:00
2. You start at 15:00
3. 19:00 – 15:00 = 4 hours

You have 4 hours to sail before the tide changes.

Try it as a mini adventure

Adventure: The Sailing Challenge

You are planning a sailing trip with your family. The tide chart shows these times:

Your family wants to start sailing at 13:00 (1:00 in the afternoon). How long can you sail before the tide changes?

1. Next tide is low tide at 18:00
2. You start at 13:00
3. 18:00 – 13:00 = 5 hours

You can sail for 5 hours before the tide changes. Great planning!

Challenge: Now, try this: You want to start sailing at 09:00. What time is the next tide?

1. Next tide is high tide at 11:30
2. You start at 09:00
3. 11:30 – 09:00 = 2 hours and 30 minutes

You can sail for 2 hours and 30 minutes before the tide changes.

Common mistakes

• Mistake: Thinking 13:00 is 1:00 in the morning, not afternoon.
  Why it happens: Confusing 24-hour time with 12-hour time.
  Fix: Remember that 13:00 is 1:00 in the afternoon.
• Mistake: Subtracting the wrong way (like 13:00 – 10:00 = 1300 – 1000 = 300).
  Why it happens: Not separating hours and minutes properly.
  Fix: Break it into hours and minutes: 13:00 = 13 hours, 0 minutes. 10:00 = 10 hours, 0 minutes. 13 – 10 = 3 hours.
• Mistake: Forgetting that the tide changes between high and low.
  Why it happens: Not understanding that tides are not always the same.
  Fix: Look at the chart to see if the next tide is high or low.

Parent and carer guide

As a parent or carer, you can help your child by:

1. Practising reading 24-hour time with clocks or digital displays
2. Using a real tide chart or a chart from a sailing app to make it fun
3. Letting your child plan a sailing trip using the chart
4. Encouraging them to count backwards and forwards in hours and minutes
5. Using a timer or clock to show how much time passes between two times

What to say:

• "Let's look at the chart together and find when the tide changes"
• "Can you count how many hours you have to sail before the tide changes?"
• "Why do you think it's better to sail with the tide?"

What not to worry about:

• Your child may make a mistake with 24-hour time – this is normal
• They may need to count backwards or forwards – this is a great skill to develop
• It's okay to use a calculator or timer to check

Practice questions

1. What is the time difference between 08:00 and 12:30?
   Answer: 4 hours and 30 minutes
2. If you start sailing at 15:00 and the next tide is at 20:00, how long can you sail?
   Answer: 5 hours
3. What time is 14:45 in 12-hour format?
   Answer: 2:45 in the afternoon
4. You start sailing at 09:30 and the next tide is at 13:15, how long can you sail?
   Answer: 3 hours and 45 minutes
5. What is the time difference between 06:00 and 11:00?
   Answer: 5 hours

FAQ

Why do tides happen?

Tides happen because of the pull of the moon and the sun on the Earth's oceans. The moon's gravity pulls the water towards it, creating high tide, and the water moves away from the moon, creating low tide.

How do I read a tide chart?

A tide chart shows the times when high and low tides happen. You can see if the tide is high or low, and when it changes. Look at the times and match them to your sailing plan.

Can I sail in any weather?

No, it's not safe to sail in bad weather. Always check the weather forecast and tide times before going sailing.

Why is it better to sail with the tide?

Sailing with the tide makes it easier and faster. The water pushes your boat along, so you don't have to row as hard.

How do I know if I'm ready to sail?

You should check the tide times, weather, and make sure you have the right safety gear. If the tide is changing soon, plan your trip so you can sail before it changes.