What to check on a Line Throwing Apparatus.
Getting a line across open water to another vessel, a person in the water, or a shore party is harder than it looks: a thrown or floated line rarely covers useful distance against wind and current. A line throwing apparatus solves this with a rocket or pistol-fired projectile that carries a light messenger line out to 230 metres or more, which can then be used to haul across a heavier towline, a rescue line, or a mooring line. It is distinct from a rescue line thrown by hand, which covers…
What sets line throwing apparatus apart
Getting a line across open water to another vessel, a person in the water, or a shore party is harder than it looks: a thrown or floated line rarely covers useful distance against wind and current. A line throwing apparatus solves this with a rocket or pistol-fired projectile that carries a light messenger line out to 230 metres or more, which can then be used to haul across a heavier towline, a rescue line, or a mooring line. It is distinct from a rescue line thrown by hand, which covers only a few metres, and from a heaving line, which is unpowered.
Main components
Launcher
A rocket-propelled or pistol-type launcher, either a reusable gun firing cartridge-propelled rockets or a self-contained single-use rocket unit, depending on the make.
Rocket and line
The rocket carries a lightweight line, flaked in a container or box designed to pay out without tangling as the rocket travels; a fouled line is the most common reason a shot fails to deliver despite the rocket flying true.
Line container / storage box
Holds the flaked line in a way that lets it run free without snagging, stored ready alongside the launcher so both are used together without delay.
Spare rockets and lines
SOLAS requires spares beyond the first set so a missed or failed shot does not leave the ship without a second attempt.
Selection and sizing
- Range: the equipment must meet the minimum throw distance set by SOLAS in reasonable weather conditions, not just calm-day test range.
- Line breaking strength: matched to what it is expected to haul across, a heavier towline needs a stronger messenger line to survive the pull.
- Shelf life: rockets and cartridges are pyrotechnic items with an expiry date, replaced on schedule rather than used past it.
Regulations and class
SOLAS Chapter III, referencing the IMO LSA Code, requires a line throwing appliance on every ship, capable of throwing a line accurately in reasonable weather to at least the minimum range specified, with a minimum number of rockets and lines carried. As a pyrotechnic item it falls under the same expiry-date and safe-storage rules as flares and other distress signals, and class surveys check expiry dates and correct stowage in a dry, accessible locker.
Typical faults
| Fault | Consequence |
|---|---|
| Expired rockets not replaced on schedule | Non-compliant at survey, and reduced reliability of the propellant itself |
| Line packed poorly in its container | Line fouls mid-flight, rocket flies but the line does not pay out cleanly |
| Damp storage of pyrotechnic cartridges | Misfire or reduced range when actually needed |
| Crew unfamiliar with aiming and firing procedure | Missed first shot in an actual emergency where a second attempt may not be possible in time |
What to look for in a supplier
- LSA Code type approval for the specific launcher and rocket combination.
- Clear, tracked expiry dating on rockets, cartridges and lines supplied.
- Stated minimum range performance data under the approval, not just a manufacturer's optimistic figure.
- Availability of training rockets or dummy rounds so crew can practise aiming without expending certified stock.
Check rocket and cartridge expiry dates against the same schedule as pyrotechnic distress signals, and store both in a dry locker away from engine room heat — heat-degraded propellant fails quietly until the moment it is fired.