A safety line (also known as harness line or tether) is intended to provide reasonable assurance that the wearer will remain attached to a craft (sailing yacht or motor cruiser) under normal loading. To do this the safety line must be securely attached to a correctly worn safety harness (which may be a lifejacket with an integrated harness) and to a suitable strong point on the boat.
The safety line (and the harness worn by the user to which the safety line is attached) should comply with ISO 12401 (You may still see EN 1095 which has been superseded by ISO 12401). Where the harness is a lifejacket with an integrated harness, the lifejacket with integrated harness should be certified both to ISO 12401 and to the lifejacket standard which deals with the level of floatation the lifejacket must provide.
Preventing the wearer from falling into the water is dependent on the location of the attachment to the craft and the length of the safety line – this is something that the wearer needs to think about carefully when clipping on. The optimum length of safety line will vary by user and by boat, based both on the size of the boat and the location of the clipping on points and jackstays. Safety lines that comply with the ISO Standard must be no more that 2m in length but at times something shorter may be required.
Mobility must be balanced against the risk of falling overboard. The safety line needs to be long enough to enable movement around the boat, but if a long safety line would allow the person to fall overboard into the water, when working in an exposed position a shorter safety line should be used.
A common solution to the need for safety lines of longer and shorter lengths is a mid-point hook. This allows the user to change the clipping on point without being detached from the boat and the user has a shorter safety line to hand when one is needed.
Safety lines can only work effectively if there are adequate attachment points on the boat. Guardrails are not built to take the loads imposed by a safety harness and should not be used as attachment points.
Attachment points adjacent to the exit from the accommodation space which facilitate clipping on before leaving the safety of the accommodation are recommended, as are clipping on points adjacent to an exposed steering position. A jackstay running the length of the boat is useful to facilitate clipping on before venturing onto the exposed side decks and remaining attached whilst working on the deck. Further strategically placed clipping on points may also be beneficial for example at the mast for reefing. It is vital that attachment points and jackstays are well maintained.
Jackstays should be placed as close to the centre of the boat as is practical to help reduce the possibility of somebody falling over the side as well as keeping them attached to the boat. This is particularly important if a boat has a low freeboard, as drowning is still a possibility if you go over the side even if you are still attached to the boat.
Anyone falling overboard from a motor cruiser at speed potentially risks serious injury so it is particularly important to have harness attachment points close to the centre of the deck to prevent this. It is also important that the attachment points are positioned to prevent the possibility of a casualty being dragged into the propeller.
Safety lines can be purchased from most good chandleries and on-line. 2 and 3 hook safety lines are available from most manufacturers, some supply elasticated versions and some have an overload indicator to help you to decide when the safety line needs to be replaced (safety lines should be checked regularly for wear). However, shorter safety lines that are suitable for your boat may not be readily available and may have to be sourced from a reputable sailmaker.
The hooks on the safety line should be designed so they cannot be accidentally opened. An ISO approved safety line is fitted with hooks which have been designed and tested to prevent this.
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