English

Noun

freeboard

1. The vertical distance between the waterline and the uppermost watertight deck of a vessel
2. The similar distance between a water level and the top of something that contains or restrains it (such as a dam)

Derived terms

• freeboard deck

The term "freeboard" has multiple meanings, depending on the subject area.

In sailing and boating, freeboard means the distance from the waterline to the upper deck level, measured at the lowest point where water can enter the boat or ship.

In yachts, a low freeboard is often found on racing boats, for weight reduction and therefore increased speed. A higher freeboard will give more room in the cabin, but will increase weight and may compromise speed. A higher freeboard also helps weather waves and reduce the likelihood of green seas on the weather deck. A low freeboard boat is susceptible to swamping in rough seas. Freighter ships and warships use high-freeboard designs to increase internal volume and also allowing them to satisfy IMO damage stability regulations due to increased reserved buoyancy.

There are other various meanings of freeboard:

• Freeboard is also used to describe the height of an ice floe above the water surface. Freeboard does not include the potential snow coverage on the ice floe.
• Freeboard in water channel design is the distance from the water level to the top of the channel's sides.

Notes

References

• American Merchant Seaman's Manual
• Merchant Marine Officers' Handbook