During daylight hours, a small general cargo vessel was en route for discharging in good weather and visibility. The vessel (and crew) had often taken this same route but on this day, with the Master’s consent, they deviated from the original track as described in the voyage plan in order to save time.
However, the voyage plan was not updated at the time and the Master and officers improvised based on local knowledge. Additionally, the officers did not bother to erase the old course lines, resulting in many confusing lines on the chart. At the watch handover the deviation from the original track was discussed and the relieving officer had no problems with this deviation. The new track would lead the vessel north of a wind farm and also north of some shallows.
A little later the OOW had to alter course to starboard due to an approaching vessel. The vessel then met a number of vessels under sail so the OOW again altered to starboard. Since he was navigating principally by visual means the OOW did not appreciate how close the vessel was coming to the shallows on its starboard side. He was aware of the existence of the shallows, now straight ahead, but he had the impression that he would pass their outer limits with a charted depth of about 10.0 metres.
The OOW also knew about squat, but he assumed that an under keel clearance (UKC) of 0.7 metres would be enough to pass the shallowest part without a problem. Unfortunately, as they passed over the shallows the vessel touched the bottom twice. The vessel had to enter dry dock for repairs; there was paint damage and some scratches up to frame 88. Tank number 4 was taking water and there was damage to the propeller blades. Some cracks were also found in the rudder.
- By deviating from the original course the vessel was brought into a potentially busier area where more yachts and pleasure craft could be expected.
- It is better to navigate by instruments, even in fine weather, than by ‘impressions’.
- By reducing speed, the time available to take action would be increased, the CPA with the nearest sailing boat could have been increased and the squat would have been reduced. Unfortunately, the OOW did not avail himself of this option.
- Always use a chart which is in a good and updated condition. Old and non-used course lines must be erased.
- Trying to find short cuts in order to save (some) time is not a valid argument. The primary concern must always be the safe navigation of the vessel.
- If an ad hoc deviation is made, the voyage plan should be adjusted accordingly.