Bulb keel

[1] The purpose of the bulb keel is to place the ballast as low as possible, therefore gaining the maximum possible amount of leverage and thus the most righting moment.

An example of a class of boats that use a bulb keel is the International 110 racing class, which uses a 300 lb (136 kg) cast iron bulb keel on a boat whose minimum racing weight is 910 lb (414 kg).

It is also possible to shape the bulb into a horizontal foil, called a winged keel.

When the bulb protrudes past the leading edge of the keel, it is called a "T-bulb".

It offers better performance (like required for racing), but is prone to hook into flotsam (like kelp or discarded fishing nets).