Winch Sheared

Outline:

A sailing yacht suffered a winch failure whilst hoisting the mainsail when departing harbour.

What the Reporter told us:

After leaving harbour the mainsail was being hoisted under normal load when the mast halyard winch sheared off its mounting. Closer examination of the winch identified that the centre stem casting had failed.

The winch, which was manufactured by a well-known name in yachting, is only 3-4 years old and, furthermore, the boat is only used for fair weather cruising – never raced.

Since use of the main mast halyard for man overboard recovery is a recommended practice, a failure such as this could have been catastrophic. Further, we were informed that the winch has never been subject to heavy load or severe shock.

Photograph of failed casting.

Further Dialogue:

CHIRP learnt that the incident had occurred one month prior to the report being submitted. Initially the reporter had corresponded with the winch manufacturer who had offered to send the failed component away for engineering analysis with the proviso that if there was no fault found with the casting then the reporter would be liable for the costs involved, a sum in excess of £1,500. The reporter declined the offer but advised the manufacturer that as it was a safety concern, he would be submitting a report to CHIRP to see if his was an isolated incident or not.

Subsequently the reporter received a further e-mail from the manufacturer stating, “that although they have a very low failure rate of these winches, on this occasion as a gesture of good will they would send the reporter a new replacement centre stem”. This was duly done.

Meanwhile CHIRP sought expert advice and opinion as to the failure – it was confirmed that similar failures had not been reported and were thus unknown. In addition, the manufacturer was indeed well respected for the quality of  its products.

CHIRP Comment:

Members of the MAB raised the following points concerning this report:

• leisure boat construction, including equipment and fittings, cannot be presumed to be as robust as commercial vessel construction. A deep-sea vessel built to Lloyd’s classification will have each aspect of the construction inspected and signed off by a Lloyd’s surveyor. Equally, all class machinery and equipment installed will be individually inspected and approved. In the case of leisure craft, many are self-certified by the manufacturers themselves. Much of the equipment is bought in, with the components being fabricated on a batch and line QA process – the components are then assembled during final installation of the craft.
• it was noted that the MCA are reviewing the current Leisure and Pleasure Boat Code.

In addition to using the main halyard and winch for recovery of a man overboard in an emergency, it is also a common practice to utilise masthead halyards and winches to hoist crew members aloft for routine work. In the latter cases it is recommended that two lines are utilised, one to hoist aloft and the second as a safety line.

Reports Ends…………..