Line-Throwing Apparatus

What a line-throwing apparatus does

A line-throwing apparatus (LTA) launches a rocket or pistol-fired projectile trailing a light messenger line to a distance no unaided throw could reach. It is not a distress flare and not a lifebuoy self-igniting light: its only job is to close the gap between two points, ship to ship, ship to shore, or ship to a person in the water, so that a stronger line, a heaving line, a pilot ladder tackle or a breeches buoy can be hauled across afterwards. SOLAS carries it as a standalone lifesaving appliance separate from pyrotechnic distress signals, even though both often live in the same locker.

Main components

Rocket or cartridge

A solid-propellant rocket, or in pistol-type sets a blank cartridge, provides the launch energy. Rocket sets are self-contained and hand-held; pistol sets use a reusable line-throwing gun with disposable projectile-and-line cartridges.

Messenger line

A light, low-stretch line, typically polyethylene or similar synthetic, flaked in a container or on a purpose-built line tray so it pays out without snagging. Breaking strength is modest; the line is meant to pull a heavier line across, not to take load itself.

Line container / flaking box

Keeps the line coiled in a figure-eight or flaked pattern so it runs free during flight instead of fouling in the air, which is the single most common cause of a failed shot.

Launcher

Either integral to the rocket, fire-and-discard, or a separate pistol or gun that is reloaded for each shot; sets intended for repeated pilot transfers favour the reusable gun over disposable rockets.

Selection and sizing

Range and line payload decide the set. SOLAS requires a minimum four-rocket set capable of throwing a line at least 230 metres in calm weather, but ships with regular pilot transfer or working close alongside other vessels often carry additional pistol-type sets with shorter, more controllable range for routine line passing rather than emergency rescue. Line weight is a trade-off: a heavier line reaches less far but tolerates more wind drift without needing to be re-thrown.

Regulations and class

• SOLAS Chapter III, Regulation 18 requires every ship to carry at least one line-throwing appliance capable of projecting a line with reasonable accuracy.
• The set must include no fewer than four projectiles and four lines, stowed ready for use in a location not likely to be adversely affected by weather.
• Rockets fall under dangerous goods handling rules for stowage and disposal once expired, since they contain pyrotechnic propellant.
• Class surveys check expiry dates at each periodical lifesaving appliance survey; expired rockets must be landed and replaced, not just noted.

Typical faults

What to look for in a supplier

• Current type approval certificate referencing the applicable LSA Code testing standard.
• Clearly marked expiry dating on every rocket or cartridge, not just the outer set packaging.
• A line-flaking method demonstrated, not just described, to run clean on deployment.
• Availability of individual replacement cartridges rather than only complete sets, for ships that drill regularly.

Practice throws should use a designated drill set, not the certified emergency set; burning through the mandatory four rockets in a training exercise leaves the ship short when it actually needs them.