bilge pump finished

This is a bilge pump we made as a project. 

You can make it too… The link is at the bottom of this  page.

It draws water from the lowest part of a boat hull.

You can only pull water up to a height that is the same or a little less than the length of the tube

or CYLINDER of the pump.

In a ship the cylinder is as long as the ship is high from the keel to the deck.

In our project the cylinder is 30 centimeters long and some of that, say 2 centimeter is needed for:

the “foot valve”

and the “gland” or cork stopper at the top of the pump.

The pump outlet is also about 2 centimeter below the top so you can draw water about 26 cm up from a lower level.

The “piston” and the cylinder are at the heart of the pump.

The piston fits tightly in the cylinder and when you pull up the piston it sucks or draws the water up, as high as 10 meters if the cylinder is that long or a little longer.


Draw water any higher and it evaporates and becomes a gas, you draw a VACUUM!

At the cottage, you can not draw the water up if the cottage is 10 meters above the lake level. If the cottage is higher than 10 meters then you need to draw water and then press it up at the same time, with the pump somewhere between.

This is the same if the ship’s deck is more than 10 meters above the keel or bilge.

The “foot valve” opens up when you draw water into the cylinder.

At the top of your draw, and when you push the piston down, the foot valve closed.

The marble drops on top of the rubber hose by gravity and water pressure and keeps the water  in the cylinder.

When the piston is pushed down the rubber piston cups upwards and lets the water go by its sides.

When  you pull the piston up from the bottom, it pushes the water above it out of the pump.

At the same time it draws water up:


with each stroke downwards and upwards.


There are many kinds of pumps: single and double-acting piston pumps, centrifugal pumps, gear pumps and more…Just Google pumps and see what you can find!

Here are a few…

water crank pump

This is a hand driven water pump that you still can find around some houses and farms to pump water from a well or lake.


water external-gear-pump

There are even gear pumps, two spur gears working together to move water around from the inlet side to the outlet side.

They pump water or other fluids and these pumps are working very well to pump smaller quantities.

They  fit in small places .


water screw pump

This is a screw pump to lift water over a small distance uphill.

They were used in “polders” or drying of land, also called landreclamation.

It removes water from low lying land to use it for growing grains and other agricultural uses.

It was invented by Archimedes a scientist and engineer who live more than 2200 year ago.


water centrifugal pump

A cross section of a centrifugal pump.

The rotor runs fast around and it sucks in the water through the center.

Centrifugal forces push the water to the outside of the impeller and then to the discharge.

The pump can mover a large volume of water over short distances to a higher level. 

water pump kingston pur plant

These are centrifugal pumps in a municipal water pumping station of our city.

They move large amounts of water day in day out.

These pumps were built in 1917 and have worked  day after day for almost 100 years!


Have fun building  your own WATER PUMP!


Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s