Correspondence Received – Incorrect windlass brake band adjustment

On many vessels I have sailed on we have the same situation – the bosun tightens the bolts and chief officers and masters do not pay any attention to this problem. But the consequences of this wrong adjustment are slow speed of winch, damage to the brake liner, slackening of ropes and anchor and possibly injured crew members, hydraulic oil spills and damage to the vessel. The following investigation report was made by a previous company I worked for:

Following the windlass brake failure and subsequent loss of the starboard anchor and all 12 shackles of chain aboard one of the company’s vessels, the opportunity was taken to thoroughly investigate the possible cause of failure by inspecting the starboard windlass and braking mechanism aboard the sister vessel.

With the starboard anchor and chain tightly secured using the guillotine bar and a wire rope stopper, the weight was removed from the windlass brake. The brake band adjusting bottle screw and fixing plates were removed to the engine room workshop where the threads were thoroughly cleaned and lubricated.

On refitting the fixing plates and bottle screw the adjustment of same was kept to a minimum with only approximately 5 threads entered at both ends of the screw. The brake was then fully applied using the strength of two able seamen. With the drive clutch engaged, the hydraulic motor turned the windlass gypsy wheel with ease and there was absolutely no braking effect.

 The reason for the freedom of movement was that the crosshead, located between the brake application shaft and the brake tensioning plates, was in contact with the windlass foundation, as shown in the photograph below:

       

Incorrect brake adjustment                                          Correct brake adjustment

 

The bottle screw was then tightened to the correct setting, i.e. allowing the gypsy to rotate freely in the brake ‘off’ position, but in the brake ‘fully on’ position the hydraulic motor could not rotate the gypsy. The clearance between the crosshead plates and the foundation with the brake fully applied was in the region of some 30 – 35mm.

 

     

                                                                   Brake “fully on”                                       Bottle screw adjustment

Both port and starboard foundations were showing signs of contact with the crosshead plates, therefore it would seem that it is not uncommon, on this type of windlass, to have the brake tensions incorrectly set.

Conclusion: The loss of the starboard anchor on board the sister ship was probably due to incorrect brake adjustment.

Corrective Action: With immediate effect, all  in the same class are to strip down and clean the internal and external threads of the bottle screw arrangements, insuring that before removal the anchors are fully secured using the lashing wire and compression bar.  With the bottle screws refitted the brakes are to be adjusted to give 30 – 35 mm clearance between the foundation and the crosshead plates when the brake is ‘Fully On’.  To test the holding ability of the brakes, engage the drive shaft clutch, with the brake ‘Fully On’ and try and rotate the drum in a chain lowering direction using the hydraulic motor, there should be no motion of the gypsy wheel relative to the brake.

Prior to every anchoring operation it is the responsibility of the deck officer in charge on the forecastle deck to apply the brake fully and report to the master that there is a suitable 30 – 35 mm gap as previously described. (The engine department is to manufacture a two ended feeler gauge, one end with a 35mm thickness the other a 30mm thickness, this gauge is to be kept by the bosun who will measure the gap in the presence of the aforementioned deck officer).

Training:  All personnel involved in the anchoring operation and the maintenance of the anchoring equipment are to be trained by the Chief Engineer and Chief Officer in the correct procedures prior to being permitted to operate or carry out any work on the equipment.  The senior personnel are to include this message in their handover notes and give instruction to their relievers.

 

 

 

Report ends……………………….

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