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Part Of The Keel Damage |
Early on August 9 we departed Potts Harbour, heading for Booth Bay, Maine. Leaving the anchorage we collided with a submerged reef, bringing the mighty Crystal Blues to an instant stop from around 5 knots. Ouch. Our first computer assisted grounding!
Fact is, we were lucky. The mast and rig stayed up, the hull was not breached and the damage could be repaired fairly simply. However a boat built less heavily would have been in severe trouble. The story that follows is intended to serve as a warning for others, to help prevent further accidents. So how did it happen ?
First off, I made the mistake of trusting Navionics Sonar Charts, which I'm unlikely to do again. Secondly, I failed to check any secondary navigation aids or references. So with more care I could have avoided the reef. Dodging lobster pots, early in the morning, I was busy at the helm and trusted the charts that had brought us into harbor the afternoon before.
Never again...
It's ironic that I was actually looking at the charts (on the iPad) as we connected with the reef - when Ley stumbled up the companionway and I picked myself up off the wheel, we both looked at the chart on the iPad - it showed over 13 meters of water depth. Wrong.
In fact very wrong.
Crystal Blues was at that point bobbing on the gentle swell, afloat, but occasionally colliding with the reef on the bottom of the swells and occasionally hitting something as she rocked from side to side. Not wanting to start the engine in unknown waters, we lowered the dinghy and towed her away to deep water using the outboard motor. We lifted the floor boards and inspected the bilges for damage or leaks, and then (more than a little shaken) proceeded to Booth Bay, where I dived on the boat and captured the image above.
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Pulling Away From The Reef |
So now, over three weeks later, we're hauled out of the water at Journey's End Marina in Rockland, Maine, working towards repairing and refinishing the keel. In the time since the accident both we and others have had time to look at the Navionics charts for the area in some detail, and the results are not good.
The Missing Reef
First of all, this problem has
nothing to do with zoom levels on the screen. No matter how close in you zoom, that reef was not shown. So here is what we were viewing on screen right when the collision occurred :
With the wisdom of hindsight, it does look weird. The yellow line is our track, and it shows just over 13 meters where we came to a sudden stop. When we checked the standard Navionics chart (not the Sonar Chart version), a serious chart error became apparent :
You can see that this version shows a depth of 5.4 meters nearby, and the dark blue zone adds to the message that we shouldn't be there. However it gets worse, much worse.
The official government chart, above, shows a minimum depth on that reef of less than 1 meter. Yoiks ! So, not only the Navionics
Sonar Charts were wrong, but also the "standard" Navionics charts. How can this be ? How widespread is this problem ?