What is the most obvious feature about a boat? It floats. However it needs to float in such a way that it is useful. It needs to be able to carry a load (even if that load is just a couple of mates out for a day’s fishing); it must have a hull that is safe and easily driven; it must be able to withstand the stresses and strains of operating at sea and it must be stable.

What is Stability?

The Macquarie Dictionary gives the definition:

‘the ability of a ship to return to its upright position when laterally displaced’.

This is a bit difficult to understand, but most people have a sense of a vessel’s stability. If a boat does not tip easily when a load is placed in it, if she is comfortable in a seaway without excessive motion and if she comes back upright when heeled over, then we say that she seems to be stable vessel and our confidence in her is increased.

In this section we will look at what makes a vessel stable, how we can assure she stays that way and what measures we can take if we think our stability is reduced. We will consider how the movement of weights in the vessel affects the stability and how to best manage the loading of weights in the vessel.