The Anne Marie Houseboat for sale

 

• Name: FCB (FerroCement Barge)

• Number manufactured: 200

• Year of manufacture: Unknown (the barges were built between 1940 and 1945 and we believe our barge was built at the end of this period)

• Engineering: Mouchel Ltd

• Building: Wates Ltd

• Where built: London

• Construction material: Steel mesh reinforced concrete panels.

• Use: Water/fuel barge

• Weight (Empty): 160 tons

• Weight (houseboat):  200 tons

• Length overall: 25.6m (84')

• Beam: 6.9m (22' 6")

• Draught (empty): 1.1m (3' 8")

• Draught (max load): 2.4m (8' 1")

• Cargo capacity: 185 tons

• Number of separate hold compartments: 3 main and 2 at bow and stern.

• Tidal height required to float: Currently 4.7m but is slowly increasing, ten years ago the figure was 4.4m. 

 

How does a concrete vessel float?

It does seem strange that a vessel (the Anne Marie) made of concrete will float quite happily. This is because of Archimedes' principle:

 

The upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces. As long as the weight of water it displaces is more than its own weight then it will float.

 

It is all a matter of density, the density of an object is its mass divided by its volume. To float, the vessel must be less dense than the same amount of water. A solid, cube of concrete is much more dense than the same cube of water and will sink like a stone. When the same amount of concrete is formed into the shape of a boat, with much of the interior nothing but empty air, the ship's total volume also includes the air. Air is much less dense than water and since the total ship is a combination of air and concrete, the density for the whole ship becomes less than the water, allowing it to float. If the ship should develop a leak, water rushes in and forces the air out of the hull causing the density of the ship to become greater than that of the water and she will sink.