Sep 062008

Compared to other launch systems,
free-fall lifeboat accidents are relatively rare.
This one was just a drop in the ocean.

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Free Fall Lifeboat Hazards – A Drop In The Ocean

 accident reporting, lifeboat, lifeboat accidents  Comments Off on Free Fall Lifeboat Hazards – A Drop In The Ocean
Sep 012008

As a backgrounder to the forthcoming The Case Of The Fallen Saviour podcast:

Freefall lifeboat concepts have been around for 110 years. The earliest known patent was issued to AE Falk of Stockholm, Sweden, on 30th March 1897. It was to be stern-launched from a ramp at a height of three metres.

It next surfaced as a suggestion by a Captain White of the Bay and River Navigation Company is the US. The US Department of Commerce Bureau of Marine Inspection and Nagivation considered the idea too dangerous to put into practice.

In 1959 the modern-type of freefall lifeboat came into being. A Dutch sea captain approached yacht-builder Joost Verhoef of Aalsmeer, Netherlands with an idea for a freefall lifeboat. Verhoef designed and built the first such lifeboat of aluminium and the design went into service in 1961 but was not popular with shipping companies, being significantly more expensive that traditional davit-launched designs.

The advantages of a design that could be launched safely under a wide variety of sea conditions and list was not appreciated until 1973 when, after two serious ship incidents the Norwegian Maritime Authority commissioned the Norwegian Ship Research Institute to design a launch system with was tested in Hardanger Fjord in 1976 from a height of 20 metres. The first manned launch took place from the m/s Tarcoola the following year and the design was formally approved 1978.

Freefall lifeboats came into their own in the offshore industries following the Pipe Alpha disaster.

Although freefall lifeboats are regarded as safer than davit-launched lifeboats, and have been used successfully in at least two maritime incidents, they do have their shortcomings, in particular with the evacuation of injured personnel.

Less complicated more reliable, due to the simplicity of the fundamental design, than davit launched lifeboats, freefall lifeboats have one potential area of hazard which they share with davit-launched designs and three in particular which are unique to the freefall design.

As with davit-launched boats, poor training, drills, lack of safety awareness, unclear manuals and signage can lead to confusion that may result in accidental launch and subsequent injury of personnel not properly seated and secured.

Unique to freefall lifeboats is the issue of potential injuries to occupants when launched from height, in particular the coxswain. While the occupants face towards the stern during the launch, the coxswain must face forward, which, even if restrained, can lead to back injuries. One solution has been to incline the coxswain seat to reduce the risk of injury, a position which puts critical lifeboat control out of reach during launch and it may be difficult for the coxswain to recover from the launch position to take command.

A second element is the need to attach slings during drills and maintenance as is apparent from this report from the Britannia P&I Club.

In that case a freefall life released unexpectedly when restraining slings failed during a drill. Three crewmembers onboard suffered only minor injuries, despite a considerable drop, because they were properl;y strapped in.

Investigation of the sling showed that it had been cut through in way of the securing grip, possibly by thieves intending but failing to steal it. The slings had not been supplied by the lifeboat manufacturer and may not have met the appropriate specifications.

One should check slings before use and ask ‘is there a certificate showing that your slings are fit for purpose? Is it onboard?

A further issue specific to freefall designs is the effect of impact on the forward part of the lifeboat, in particular the forward window and the superstructure.

A freefall lifeboat was damaged during a test on Veslefrikk B offshore facility on the Norwegian Shelf on 21 June 2005. The report by Veslefrikk B operator Statoil concludes that the superstructure of the relevant lifeboat may have had manufacture and/or design flaws.

Norway’s Petroleum Safety Authority reports: “The PSA asked the supplier of this type of lifeboat – Umoe Schat-Harding – to inform all of its customers that use FF 1000-type lifeboats about the incident on Veslefrikk B…Statoil’s investigation report does not provide any clear conclusions as to why the damage occurred, but the company has appointed a new group which has been given a mandate to identify the flaw. Since the causal relations are unclear, Statoil cannot rule out that the weakness on the free-fall lifeboat has relevance for comparable types of free-fall lifeboats…Based on the investigation report, Statoil concluded in the meeting with the PSA that the company is in doubt concerning the quality of these lifeboats as a means of evacuation during all types of weather conditions..The Petroleum Safety Authority Norway shares this doubt.”

Subsequently, The PSA attempted to collaborate with the OLF, the Norwegian Oil Industry Association but withdrew due to lack of input from the industry.

While that issue may have been resolved – Schatt-Harding recalled six freefall lifeboats from offshore rigs for strengthening – it should be noted that core concept of the lifeboat, whether freefall or davit launched, is as a use-once evacuation mechanism, not as a ‘people carrier’. Mandatory requirements focus on launch rather than recovery and, while most lifeboat designs will meet the criteria for launch they may not be designed for repeated launch and recovery and may not be fit for such purpose.

Put simply, lifeboats are not designed to be durable, something of particular concern with regard to hull strength, a critical factor in the safety of freefall lifeboats. A 1993 study2 suggests that fibreglass hulls can, over time, loose as much as 50 per cent of hull strength, something especially undesirable in a freefall lifeboat.

Such weakness may not be apparent during shipboard use, given the relative infrequency of launches of freefall lifeboats, and may not become apparent until launched under particularly stressful conditions.

An example is a training school which acquired a 13 year old freefall lifeboat for training purposes. The lifeboat was fully consistent with mandatory requirements. During one launch the forward window in the coxswain’s position popped out of its frame and damage was caused to the coxswain’s seat, with the potential of serious injury to the coxswain. During another launch, set screws fixing the propeller shaft to the engine transmission sheared, the shaft and propeller being pulled partway out of the lifeboat.

It would appear evident that factors in including age of lifeboat, the number of launch cycles and the height of launch – which will influence the mechaincal stresses which it undergoes – need to be considered in maintenance and replacement schedules.