Centreboard

The retractability allows the centreboard to be raised to operate in shallow waters, to move the centre of lateral resistance (offsetting changes to the sailplan that move the centre of effort aft), to reduce drag when the full area of the centreboard is not needed, or when removing the boat from the water, as when trailering.

The centerboard, daggerboard or bilgeboard can be used as a recovery platform upon which to stand, providing increased leverage, in the event the dinghy overturns via a capsize or turtle.

A long narrow centreboard produces less drag than a short, wide one for a given amount of lift, resulting in a faster boat that can point closer into the wind.

A retracting centreboard is more complex than a fixed keel, and most take up space inside the hull of the boat that could otherwise be used for passenger accommodation.

This also provides a measure of safety should the boat run aground—the force of impact will push the foil back into the centreboard trunk, rather than breaking it, as might happen if the board were locked in place.

On larger sailing vessels, a similar design is sometimes incorporated to facilitate better navigation in shallow water than a fixed keel would allow.