Incident No. 11 - A cheap but priceless early warning

10:31 PM Sun 13 Sep 2009 GMT

'Bow thruster showing exposed power cables and damage' .

The best mistakes to learn by are other people's. This is especially so with sailing.
In this anecdote, the eleventh of a series, we present a real sailing situation which was investigated by the Marine Accident Investigation Branch (MAIB), and SIX lessons deduced. Can you identify the lessons? (Find the answers at the end of the story)

A new, 14m sailing yacht was being manoeuvred from her berth at the beginning of a weekend's sailing. The skipper used the engine and, for just a few seconds, her 12 volt, motor-driven bow thruster, installed in a compartment beneath the double bunk in the forward cabin. She had just cleared her berth when the smoke alarm sounded in the empty forward cabin.

The crew found smoke coming from the space beneath the bunk. They lifted the bedding clear, removed the compartment's covers and pulled out the spare sails and other gear. Using a dry powder extinguisher, they extinguished burning and smouldering material.

Machinery space without warnings can easily be mistaken for a storage locker - .. .

Meanwhile, the skipper requested assistance and manoeuvred back to the berth, where shore firefighters assisted in making the vessel safe.

Negligible damage was caused to the boat, but most of the bedding and spare kit was affected by fire, heat or smoke.

A closer examination found that a metal cover to the brush gear of the bow thruster's motor had been displaced. The cover had then made contact with a terminal on one of the motor's power cables, causing arcing. This sparking had ignited a sail bag.

Click here for the SIX lessons that the MAIB deduced.

Sail-World Cruising is grateful to MAIB for its permission to use these incidents

To try your hand at the previously published incidents, along with the lessons, click the following links:

Incident No. 1

Incident No. 2

Incident No. 3

Incident No. 4

Incident No. 5

Incident No. 6

Incident No. 7

Incident No. 8

Incident No. 9

Incident No. 10

by MAIB/Sail-World Cruising