A Costly Grounding

Report Text:

I left the lock in my power boat.  It was early afternoon, the weather was fine and the sea was a near flat calm.  We were half an hour off a low spring tide.

I had three people on board and intended simply to run down the channel for 30 miles or so, cross over and then return, which would take about three hours. Although a reasonably experienced sailor, this was my first power boat which I had owned for about a year.

I was number two out of the lock gates, the boat in front being a large recreational fishing boat. As we entered the navigable channel, the fishermen cast their lines from rods.  I backed off and came slightly to the port side of their vessel to ensure I didn’t snag their lines.  My speed was no higher than six knots and they were doing the same sort of speed.

Without any warning my boat stopped dead. I immediately selected neutral on both engines which continued to tick over. Having made sure the other two people on board were ok and that they had their life jackets on I went below to check the integrity of the boat.  There didn’t seem to be any damage and certainly there was no water entering the boat. I decided to try and see if the boat would move but it was stuck fast.

I contacted the Harbour Control by VHF and informed them of my predicament.  They could clearly see my vessel on the edge of the navigable channel. I did not declare an emergency but recognised that if I had ropes wrapped around my props and they were tethered in some way then as the spring tide changed to flood I would quickly have the stern under water.  We were now on a turning tide!

I considered my actions for what seemed like 20 minutes but was probably no more than 2 minutes. I decided to try and raise the out-drive legs and free the boat. The boat continued to be stuck fast and I couldn’t see what was holding it back.  I began to consider that maybe she was aground but my fear remained that I had rope around the stern which would hold her down!

Going over the side to investigate didn’t seem a sensible option.  I decided to try and get free by driving her astern.  Before doing so I got the crew to prepare to launch the life raft.  This gave them something to do and also made me feel better!

I then got the crew holding on and powered the boat backwards.  At just before full power she suddenly moved and was floating.  The engines drove her astern for about 20 metre at which point I put the engines in neutral. Another check of the boat confirmed that there was no apparent damage and certainly no water ingress.

However, when I tested the engines the boat wouldn’t go above two knots!  I had obviously damaged my out-drives/props. I crawled back into the locks and got back to my berth.

When my boat was lifted it was confirmed that I had driven my boat onto rocks.  The props were almost nonexistent although I think that that’s more due to me driving it off rather than the initial incident. Another skipper informed me that he had replaced his engine in the last week because he did exactly the same thing less than two weeks before.

Throughout my incident I was in touch with the lock control and they couldn’t have been more professional or helpful. I caused this problem and although my good intentions cost me a couple of thousand pounds I very much put the cost down to experience.

Lessons Learned.

  1. Be more aware of the full effects of spring tides.
  2. Recognise how potentially dangerous it is for a boat to stop dead even from a low speed. The boat stops but the people don’t! At 30 knots I dread to think of the impact on the people on board.
  3. If you can avoid it don’t go out from restricted water at low water on a spring tide.
  4. Take more note of strong tidal flow.
  5. Consider slowing down in a restricted channel rather than moving to the edge of the channel if you need to avoid a vessel in front of you. After all the extra 5 minutes means nothing when on this sort of trip.
  6. Lessons for others include don’t start your recreational activities such as fishing until other vessels can safely get round you even though you may be within your rights to so do.
  7. It turned out that several vessels had had the same problem as me in the weeks before.  Immediately after my incident, warnings were being put out that there were some uncharted obstacles outside the locks.  It would have been useful if this general warning could have been made beforehand although I tender no criticism of the controllers!

CHIRP Comment:

We were pleased to read the reporter’s description of the lessons learned.  It is always good that the skipper and those on board endeavour to identify the lessons from accidents and near-misses.

We also suggest the following general lessons:

  1. Passages should be planned. A passage plan would have identified the risk of grounding.  The techniques of passage planning can be obtained from an appropriate RYA course and certification.
  2. Sounding around using a pole or boat hook may possibly have given an indication on whether the boat was aground on soft mud or hard ground, or fouled by ropes, or possibly may have hit the sinker of a navigation buoy.
  3. It appears from the report that the vessel was not in immediate danger whilst she was aground. It may well have been the use of full astern power in driving her astern from the grounding position that lead to the damage. With hindsight, it may have been useful to have spent more time considering the options.  This could for example have included a tidal calculation to estimate when the boat would have re-floated with the tide without so much engine power.  (If this had been adopted, use of an anchor to hold the vessel whilst re-floating may have been appropriate.) 
  4. In general, it is useful to think about contingency plans for various eventualities, including grounding, engine breakdown, man-overboard etc, and to discuss these with your crew. Where appropriate, contingency plans should be practiced, particularly man overboard.
  5. It was prudent to contact the Harbour Control as soon as the incident occurred, as the reporter did, so they would be on the alert had the situation worsened. In other areas, it would have been appropriate to notify the Coastguard.