Helena Frye
In sailing, a boom is a spar (a pole) that runs along the foot of a fore and aft rigged sail. It improves control of the angle and shape of the sail, keeping the foot flatter when the sail angle is away from the centreline of the boat. The boom also serves as an attachment point for more sophisticated control lines, such as a downhaul, which increases tension on the luff (forward edge) of the sail. On smaller boats, such as dinghies, the boom is used to control the angle of the sail to the wind, while on larger boats, this function is largely assumed by the traveller and the main sheet.
| Characteristics | Values |
|---|---|
| Definition | A spar (pole) along the foot of a fore and aft rigged sail |
| Function | Improves control of the angle and shape of the sail |
| Primary action | Keeps the foot flatter when the sail angle is away from the centreline of the boat |
| Additional function | Serves as an attachment point for more sophisticated control lines |
| Sail type | Rare to find a non-headsail without a boom |
| Storage | In some modern applications, the sail is rolled up into the boom |
| Sail control | The sheet is attached midway along the boom or at the free end |
| Sheet attachment | Typically by means of a block |
| Block attachment | Typically by means of a bail, a U-shaped piece of metal, flattened at the ends to allow attachment with screws or rivets |
| Effect on sail angle | Controls the angle of the sail to the wind on each point of sail |
| Effect on twist of sail | Used to adjust the twist of the sail to present the luff of the sail to the wind all of the way up the mast |
| Effect on wind | Allows the sail to go out to a full 90 degrees, preventing the wind from spilling off predominantly to one side |
| Use case | Can be used to keep a smaller boat from banging into a larger boat when anchored |
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What You'll Learn
- The boom is a pole that runs along the foot of a fore and aft rigged sail
- It improves control of the angle and shape of the sail
- The boom is used as an attachment point for more sophisticated control lines
- The sheet is attached midway along the boom or at the free end
- The boom can be used to keep a smaller boat from banging into a larger boat
The boom is a pole that runs along the foot of a fore and aft rigged sail
In sailing, a boom is a spar (a pole) that runs along the foot of a fore and aft rigged sail. It improves control of the angle and shape of the sail, keeping the foot flatter when the sail angle is away from the centreline of the boat. The boom also serves as an attachment point for more sophisticated control lines.
The sheet is attached midway along the boom or at the free end, typically by means of a block. The block is usually attached to the boom by means of a bail, a U-shaped piece of metal, flattened at the ends to allow attachment with screws or rivets. On smaller boats, such as dinghies, it is used to control the angle of the sail to the wind on each point of sail.
Moving the car from side to side alters the angle of the boom to the centreline of the boat while minimising the effect on the twist of the sail. A boom will frequently have these additional sail control lines attached: a downhaul may be attached to the boom near the gooseneck to pull the boom down and increase tension on the luff (forward edge) of the sail. If no downhaul is present, the gooseneck is usually fixed vertically to the mast and a cunningham may be used to control luff tension.
In some modern applications, the sail is rolled up into the boom for storage or reefing (shortening sail).
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It improves control of the angle and shape of the sail
A boom is a spar (or pole) that runs along the foot of a fore and aft-rigged sail. It improves control of the angle and shape of the sail by keeping the foot flatter when the sail angle is away from the centreline of the boat. This means that the sail can go out to a full 90 degrees, rather than just 80 degrees, which helps to prevent the wind from spilling off predominantly to one side.
The boom also serves as an attachment point for more sophisticated control lines, such as a downhaul, which can be used to pull the boom down and increase tension on the luff (forward edge) of the sail. On larger boats, the main sheet is used to adjust the twist of the sail to present the luff of the sail to the wind all the way up the mast.
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The boom is used as an attachment point for more sophisticated control lines
In sailing, a boom is a spar (pole) that runs along the foot of a fore and aft-rigged sail. The boom improves control of the angle and shape of the sail, keeping the foot flatter when the sail angle is away from the centreline of the boat.
The boom is also used as an attachment point for more sophisticated control lines. These control lines allow the sailor to alter the angle of the boom to the centreline of the boat while minimising the effect on the twist of the sail. For example, a downhaul may be attached to the boom near the gooseneck to pull the boom down and increase tension on the luff (forward edge) of the sail. If no downhaul is present, the gooseneck is usually fixed vertically to the mast and a cunningham may be used to control luff tension. The boom vang, kicking strap or kicker is an intricate set of pulleys (and, on yachts, a hydraulic ram) running diagonally between the boom and the lower portion of the mast.
On smaller boats such as dinghies, the sheet is attached midway along the boom or at the free end. This is typically done by means of a block, which is attached to the boom by a U-shaped piece of metal (a bail) that is flattened at the ends to allow attachment with screws or rivets. The sheet is used to control the angle of the sail to the wind on each point of sail. On larger boats, this function is largely assumed by the traveller and the main sheet is used to adjust the twist of the sail to present the luff of the sail to the wind all of the way up the mast.
When going DDW (running), booms are very effective in light wind because the air that would normally spill off the mainsail because the boom can only go out to about 80 degrees before it hits the shrouds, it can go out to a full 90 degrees. This means that the mainsail and jib are in the same plane, so the wind can't spill off predominantly to one side or the other.
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The sheet is attached midway along the boom or at the free end
In sailing, a boom is a spar (pole) that runs along the foot of a fore and aft-rigged sail. The primary action of the boom is to keep the foot flatter when the sail angle is away from the centreline of the boat. The boom also serves as an attachment point for more sophisticated control lines.
Moving the car from side to side alters the angle of the boom to the centreline of the boat while minimising the effect on the twist of the sail. A boom will frequently have these additional sail control lines attached: a downhaul may be attached to the boom near the gooseneck to pull the boom down and increase tension on the luff (forward edge) of the sail. If no downhaul is present, the gooseneck is usually fixed vertically to the mast and a cunningham may be used to control luff tension.
In some modern applications, the sail is rolled up into the boom for storage or reefing (shortening sail).
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The boom can be used to keep a smaller boat from banging into a larger boat
A boom is a spar (pole) that runs along the foot of a fore and aft rigged sail. It improves control of the angle and shape of the sail, keeping the foot flatter when the sail angle is away from the centreline of the boat.
The boom also serves as an attachment point for more sophisticated control lines. A downhaul may be attached to the boom near the gooseneck to pull the boom down and increase tension on the luff (forward edge) of the sail. If no downhaul is present, the gooseneck is usually fixed vertically to the mast and a cunningham may be used to control luff tension.
In smaller boats, such as dinghies, the sheet is attached midway along the boom or at the free end. This is typically done by means of a block, which is attached to the boom by a bail, a U-shaped piece of metal flattened at the ends to allow attachment with screws or rivets. The boom is used to control the angle of the sail to the wind on each point of sail.
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Frequently asked questions
A boat boom is a spar (pole) along the foot of a fore and aft-rigged sail.
A boat boom improves control of the angle and shape of the sail. It keeps the foot flatter when the sail angle is away from the centreline of the boat.
A boat boom is typically made of a sturdy material such as metal or wood.
The sheet is attached midway along the boom or at the free end, typically by means of a block. This allows the crew to control the angle of the sail to the wind.
Yes, a boat boom can be used to keep a smaller boat from banging into a larger boat when anchored.
