# Beam (nautical)

The beam of a ship is its width at the widest point as measured at the ship's nominal waterline. The beam is a bearing projected at right-angles from the fore and aft line, outwards from the widest part of ship. Beam may also be used to define the maximum width of a ship's hull, or maximum width including superstructure overhangs.

Generally speaking, the wider the beam of a ship (or boat), the more initial stability it has, at the expense of secondary stability in the event of a capsize, where more energy is required to right the vessel from its inverted position.

Graphical representation of the dimensions used to describe a ship. Dimension "b" is the beam.

## Typical values

Typical length-to-beam ratios for small sailboats are from 2:1 (dinghies to trailerable sailboats around 20 ft or 6 m) to 5:1 (racing sailboats over 30 ft or 10 m).

Large ships have widely varying beam ratios, some as large as 20:1.

Rowing shells designed for flatwater racing may have length to beam ratios as high as 30:1,[1] while a coracle has a ratio of almost 1:1 – it is nearly circular.

## Rule of thumb - formula

The beam of many monohull vessels can be calculated using the following formula:

${\displaystyle Beam=LOA^{\frac {2}{3}}+1}$

Where LOA is Length Overall and all units are in feet.

Some examples:

• For a standard 27 ft (8.2 m) yacht: the cube root of 27 is 3, 3 squared is 9 plus 1 = 10. The beam of many 27 ft monohulls is 10 ft (3.05 m).
• For a Volvo Open 70 yacht: 70.5 to the power of 2/3 = 17 plus 1 = 18. The beam is often around 18 ft (5.5 m).
• For a 741 ft (226 m) long ship: the cube root is 9, and 9 squared is 81, plus 1. The beam will usually be around 82 ft (25 m), e.g. Seawaymax.

As catamarans have more than one hull, there is a different beam calculation for this kind of vessel.

## BOC

BOC stands for Beam On Centerline. This term in typically used in conjunction with LOA (Length overall). The ratio of LOA/BOC is used to estimate the stability of multihull vessels. The lower the ratio the greater the boat's stability.

The BOC for vessels is measured as follows: For a catamaran: the perpendicular distance from the centerline of one hull to the centerline of the other hull, measured at deck level. For a trimaran: the perpendicular distance between the centerline of the main hull and the centerline of either ama, measured at deck level

## Other beams

Other meanings of 'beam' in the nautical context are:

• Beam – a timber similar in use to a floor joist, which runs from one side of the hull to the other athwartships.
• Carlin – similar to a beam, except running in a fore and aft direction.

## References

• Hayler, William B.; Keever, John M. (2003). American Merchant Seaman's Manual. Cornell Maritime Pr. ISBN 0-87033-549-9.
• Turpin, Edward A.; McEwen, William A. (1980). Merchant Marine Officers' Handbook (4th ed.). Centreville, MD: Cornell Maritime Press. ISBN 0-87033-056-X.
North East England

North East England is one of nine official regions of England at the first level of NUTS for statistical purposes. It covers Northumberland, County Durham, Tyne and Wear, and the area of the former county of Cleveland in North Yorkshire. The region is home to three large conurbations: Teesside, Wearside, and Tyneside, the last of which is the largest of the three and the eighth most populous conurbation in the United Kingdom. There are three cities in the region: Newcastle upon Tyne, the largest, with a population of just under 280,000; Sunderland, also in the metropolitan county of Tyne and Wear; and Durham. Other large towns include Darlington, Gateshead, Hartlepool, Middlesbrough, South Shields, Stockton-on-Tees and Washington.

S138-class torpedo boat

The S138 class was a group of sixty-five torpedo boats built for the German Kaiserliche Marine (Imperial Navy) and the Ottoman Navy in the early 1900s. Almost all of the boats served with the German fleet, with only four being sold to the Ottoman Empire in 1910.

S90-class torpedo boat

The S90 class of torpedo boats was a group of large torpedo boats built for the German Imperial Navy (Kaiserliche Marine) in the early 20th century. They were Hochsee-Torpedoboot ("High seas torpedo boat") built to varying designs by Schichau at Elbing (36 vessels) and Germaniawerft at Kiel (12 vessels). German torpedo boats were designated by shipbuilder, with the first letter of their designation reflecting their builder.

Length