How do Ship Stabilizers Work

How do they help keep ships level in rough waters?

Ship stabilizers come in three main categories: bilge keels, ship stabilizers and gyroscopic ship stabilizers. Bilge keels are long thin strips of metal that run in a V shape along the length of a ship at the turn of the bilge (the area on the outer surface of a ship’s hull where the bottom curves meet the vertical sides). Bilge keels work by dampening a ship’s roll capability by counteracting roll pressure with physical hydrodynamic resistance. Bilge keels are one of the simplest and cheapest ways to stabilize a ship and mitigate roll.

Ship stabilizers differ to bilge keels in shape and positioning, resembling fins rather than gills and are often positioned in pairs at the stern and bow of a ship. They do, however, work in the same way and are usually positioned on the bilge in line with the ship’s bilge keel. Due to their larger size and protrusion, ship stabilizers offer greater resistance to ship roll but negatively affect its manoeuvrability and increase its hull clearances when docking.

Finally, gyroscopic ship stabilizers which are the stabiliser of choice on most modern, large-scale vessels – are complex fin systems that cannot only be incrementally adjusted in their angle of attack (a vector representing the relative motion between lifting body and the fluid through which it is moving) to counteract roll, but also brought in and out of the hull at will thanks to specially tailored hydraulic mechanisms.