This is the CHaOS demonstrator website, mainly intended for our student volunteers. Click here if you were looking for our main front page.

Boat Race (mk 2)

Racing boats in a large pool of water
Useful information
Kit List: 

3 boat tank sections
1 pulley unit
2 side supports
2 sets of weights on hooks
Blue plastic lining sheet
Bulldog clips to attach plastic to sides
Clamps to hold pulley board to end of tank
Various designs of vacuum-formed boat
Weights to put in the boats


NB: This experiment was retired due to the difficulties in filling/containing such a large amount of water!

*** OVERVIEW ***

The boat race is a long water tank that pulls boats through the water at constant force. We have different shaped boat hulls that you can race against each other.

Possible activities:
1. race two boats. Which boat is fastest and why? Streamlining.

Other things to talk about: Fair tests, error margins, how ships actually propel themselves.

Tips for demonstrating: don't be overwhelmed by a big crowd of children - take time to talk about the science with the two children who are racing the boats.


Ask two children each to choose a different-shaped boat to race. Count down and make sure they release the boats at the same time. One will reach the other end before another.

Ask them which one was faster and why. They should work out that it was something to do with the shape of the hull.

Why are square fronted boats slower? Mention streamlining if they're old enough. A nice demo is slicing your hand through the water with the side of your hand vs pushing water with your the palm of your hand.

Why are bumpy hulled boats slower? Trickier to explain but similar principle to above.

There should be a set of scales so you can show that the different hulls are the same weight.

Common mistakes: don't mention laminar, flow, streamlining, aerodynamic, viscocity, turbulance unless you're sure they can take it.


Fair tests - how do we know that the left hand boat doesn't always win because eg the wieght is pulling harder? What assumptions do we make? Could we repeat the test swapping the left and right hulls?

Error margins - if one boat only won by a little bit is one boat really faster than another? Or was it just because you let go of it slightly early? How would we find out? How certain are you? If you wanted to be really certain how many times would you do the test? Repeating tests. Taking averages. This is what scientists actually do.

Different hulls are needed for different jobs - a speedboat planeing hull is rubbish for carrying a large weight.

Why is this important? Shipping companies have to spend less fuel to transport, so things cost you less. What things travel by ship? Canal construction and the industrial revolution. Which takes more fuel - trains or canals? The panama and suez canals.

How are boats do boats actually propel themselves?


Possibly maximum hull speed - see for an explanation

Risk Assessment
Date risk assesment last checked: 
Tue, 08/01/2013
Risk assesment checked by: 
Date risk assesment double checked: 
Sun, 20/01/2013
Risk assesment double-checked by: 
Richard H
Risk Assessment: 

We use a 6m long shallow folding water tank (10cm) with two strings pulled by weights to show differences in designs of boats.

  • 1. Water - risk of drowning
  • 2. Slip hazard
  • 3. Finger trap in pulleys or clips on side and to the pulley board whilst experiment is in use
  • 4. Finger trap when transporting
  • 5. it is wooden so splinter hazard
  • 6. vertical piece falling over
  • 1. It is not a paddling pool, do not let kids play in it, and keep an eye on it at all times.

    If there are children in the area when setting up/clearing up/during breaks and the boat race is to be unattended, ensure that reasonable steps are taken to prevent children playing in and around it (ie temporary boundaries/hazard tape/signs)

    Do not let children step over the tank. Demonstrators should not do this either.
  • 2. Only do it outside, on a well-drained area if possible (otherwise make an effort to reduce puddles). Do not over-fill, ie. keep water well below the brim
  • 3. The main pulleys and weights are behind a screen, so not accessible. The clips should be tightly attached and the demonstrator should be watchful of children trying to remove them.
  • 4. Try to bungee down the sides of the tank
  • 5. All surfaces that could splinter have been sanded
  • 6. Ensure the vertical piece is securely attached to the heavy water tank so stable
  • if someone is lying in the water, get them out, open the airway if unconscious, and call help.
  • Call first aider, in case of other injuries
  • 0