Anchor Ran out too fast

A gas vessel was engaged in anchoring at a port where very strong tides of up to 5 knots are experienced. The vessel was anchoring at 0120, the 3rd. Officer and Bosun were at stations forward with the Master and 2nd. Officer on the bridge. The anchors were cleared and the starboard anchor made ready for letting go. The vessel was on hand steering and at 0130 reached her anchoring position. The vessel was turned to port to stem the tide and the engines were put astern. At this point there was an estimated 2.5 knots of ebb tide running. The depth of water was 20 metres, the weather was fine with a light breeze.

The propeller wash was not seen but the log showed about 0.5 kts stern way. At this point the starboard anchor was let go on the order from the bridge. The chain started to run out very quickly and the Third Officer was ordered to put on the brake. The Third Officer reported that the brake was not holding, however no report was made regarding the lay and scope of the cable. Finally the brake did take hold and the stopper was put in place.

By this time, 10 shackles had run out (there being 11 shackles on this anchor). The winch was put in gear and the chain hove back to 6 shackles in the water. Once the vessel had steadied up the anchors were screwed up and made secure.

The next morning the windlass was inspected for damage and it was seen that the brake lining had almost completely burnt away. The brake lining had to be renewed as soon as possible as the brake may not have held. If it had been necessary to use that anchor, it would have had to be " walked out".

The immediate cause for the incident was the large stern way which was estimated at 3 knots over the ground, also a contributing factor was t he lack of communication from forward to the bridge with regard to the lay and scope of the chain. The anchoring plan had been discussed with the 3rd. Officer prior to him going forward. Firstly, if the Officer had reported the lay and strain on the cable in good time then the engine could have been used to relieve the strain on the chain. Secondly, the ground speed was not properly ascertained on the bridge when the anchor was let go. The speed through the water was known, as the log display is prominent on the console and the radar. Had the GPS been checked the ground speed would have been ascertained. It was assumed, wrongly as it turned out, that in shallow water the Doppler Log goes automatically into ground tracking mode and gives speed over the ground. However this is not the case with this particular model of log.

Communications between the Bridge and the people on stations fore or aft must be good, the bridge must be kept advised of all relevant information. During manoeuvring the Officers on the bridge must be aware of the limitations of the equipment they are using and what mode they are operating in.

1. Answer the questions:

1. What type of vessel was it?

2. Where did the anchoring take place?

3. What were the conditions of the anchoring?

4. Who were at stations forward?

5. What speed did the log show?

6. What order was the 3rd Officer given?

7. What was the reason for the windlass damage?

8. What was the cause for the incident?

9. What could have happened if the Officer had reported the lay and strain on the cable in good time?

10. What kind of information must the officers on the bridge be aware of?