Beam Reach is defined as a heading perpendicular to the wind: about 90° either to the left or to the right of the direction in which the wind is blowing.
Beam Reach can be used to describe the heading of a ship - I.E. the ship is heading ~90° off to either side of the wind's direction.
It can also be used to describe the position of an object relative to the ship. For example, if an enemy ship is at Beam Reach, we must turn ~90° off the wind's direction in order to head directly towards it.
If the wind is blowing from east to west, as occurs often in the Caribbean, Beam Reach would be both North (N) and South (S). Of course, since wind direction tends to change, the direction of Beam Reach changes with it. It will always be 90° off the wind's current direction, whereever the wind is heading at the time.
Sailing perpendicular to the wind is very difficult for all Square Rigged ships. This is because their sails cannot swivel far enough to fully catch the wind, which is now hitting the ship from the side. Nonetheless, a powerful wind can still generate enough force on the sails to keep the ship moving at a low speed.
Fore-And-Aft Rigged ships, on the other hand, perform very well when the wind hits the sails from the side rather than from behind. Also, due to their normally-small size, Fore-And-Aft Rigged ships are also much easier to move through the water. As a result, some of these ships behave very well at Beam Reach, with some having it as their Best Point Of Sailing.
The Pinnace normally achieves its best speed when heading in this direction. No other ship will match its speed when traveling thusly. Barques and Sloops are slightly less apt at this heading, and may prefer a less-acute angle such as Broad Beam Reach or Broad Reach, but are by no means slow when heading at Beam Reach either.
As a result, Beam Reach can be seen as the penultimate "escape" heading for Fore-And-Aft ships - especially when facing a larger, Square Rigged vessel.
All Square Rigged ships will have reduced speed when sailing towards Beam Reach, even when the wind is strong. Nonetheless, they will continue sailing forward (barring extensive damage) when heading in this direction. Square Rigged ships normally prefer sailing at much less acute angles, such as Running Broad Reach.
Sid Meier's Pirates! (2004)Edit
In Sid Meier's Pirates! (2004), Beam Reach is a difficult angle for most ships, causing a considerable reduction in speed. This is especially true for all Square Rigged vessels, which won't be able to keep more than a low speed at this heading. Even hybrid vessels, like the Brig Class and Frigate Class, will prefer sailing in other directions, though they still perform better than purely-Square-Rigged ships.
For Fore-And-Aft Rigged ships, Beam Reach is considered the widest angle at which they still possess an advantage. Both Sloop Class and Barque Class can develop good speed at this angle even though it is not their Best Point Of Sailing, and can use this as an escape direction.
Pinnace Class ships develop their maximum speed somewhere between Broad Beam Reach and Beam Reach. Thanks to their small size, they will also accelerate to this maximum speed very rapidly once they start heading in this direction. On the lowest Difficulty setting, with a highly Upgraded ship and favourably-strong wind, a Pinnace-class vessel can sometimes reach 20 knots - which is quite fast.