The term STABILISER is related to the terms BALLAST and KEEL. BALLAST is a heavy material, such as sand or water, that is placed in the bottom of a boat to provide stability and prevent it from tipping over. KEEL is a structural element of a boat that runs along the centerline from the bow to the stern and provides stability and strength. Together, BALLAST and KEEL act as STABILISERS, helping to keep the boat upright and steady in the water.