Ballast is essential in the composition of a boat. It ensures the stability and balance of a yacht which, without the ballast, would pop out of the water like a cork! To understand how it works, you have to go back many years to when the first studies of boat buoyancy were carried out. In the history of mankind, the basics of the buoyancy principle were understood very quickly. A tree trunk floats, but a hollowed-out tree trunk floats even better. In fact, the inclusion of air in the submerged volume makes the boat float better. By combining several boards side by side to form a walnut shell, this system has been further improved. In this way, a much larger amount of air could be enclosed, which further increases the buoyancy of the boat. This meant that a much larger number of goods of all kinds could be transported.
The history of ballast, a question of balance and stability
A rather absurd problem soon arose: The boats were floating too much. This may seem absurd. After all, the main function of a boat is is that it floats. But it was the shape of the boat that was problematic. Because of its V-shape, too little of the hull surface was in direct contact with the water. It’s a bit like someone trying to step on one toe. Apart from the fact that the toe could break, the person would not be stable because the toe has too little surface area on the ground compared to the whole foot.
Then came the idea of changing the shape of the hull. The drakkars or feluccas opted for a flat bottom, which gave them greater stability. These boats were perfectly suited for rivers or calm seas. But as soon as the swell began to rise, when the waves were too great, the ship would crash far too violently into the water which could break the ship. This is because the flat shape of the hull causes the hull to be subjected to much greater impact than if it had a more bevelled shape. It’s a bit like when someone jumps off a diving board. This person would suffer far more damage by going flat than by diving vertically. This meant that the ship had to be able to go into the water but still float in a stable manner. For this reason, the shape of the hull with a pointed bottom is recommended.
Figure 3: When a flat-bottomed boat hits the ground, it suffers heavy damage
Then came the idea of ballasting the boats. But again, there are several things to watch for. Firstly, the weight of these ballasts. Too much weight, and the boat sinks. Not enough, and the boat floats too much. This may seem obvious, but it should be made clear. Secondly, the location of the ballasts. It was soon decided to place them on either side of the central axis, to correct the list of the boat. And if the first weights were made of earth or sand, at the end of the 19th century another option was introduced: seawater. It was now possible to fill and empty the tanks as required, using pumps in particular.
Where does the name “ballast” come from?
The word ballast actually originated in England in the 1520s. To describe heavy and useless equipment on a boat, sailors used the word “bar-last”. the word “bar” can be traced back to the medieval English word “bare” or “mere”, which means “simple”. “Last”, on the other hand, refers more to a “charge”. The ‘bar-last’ was a ‘simple load’, a heavy weight of no great importance, not to be confused with goods, very important heavy weights. “Ballast” is said to derive from “bar-last” and now refers to the large water tanks used to control a ship’s stability and trim.
Which ballasts are used on Berkem Group boats?
Edgard Vincens‘ Groupe Berkem boat has two ballasts on board. To increase its speed and stability, the boat was equipped with one ballast on the port side and the other on the starboard side. The skipper has full control over the filling process thanks to a pump on the boat.
Each has a capacity of 750 litres and consists of two compartments. Note that the two ballasts are never filled at the same time. The filling volume is managed according to several factors: the wind strength, the sea conditions but also according to the boat’s armour. Sometimes there will be a need for weight on the front and other times on the back, so having two ballasts is a necessity for performance and stability.