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Power voyaging near knockdown

Jan 6, 2015
The Nordhavn 52 Dirona anchored at 47 degrees south in Port Pegasus, Stewart Island, New Zealand.

The Nordhavn 52 Dirona anchored at 47 degrees south in Port Pegasus, Stewart Island, New Zealand.

James and Jennifer Hamilton

We bought a strong, ocean-capable voyaging boat. We chose Dirona, a Nordhavn 52, not because we were convinced we would voyage ‘round the world, but because we wanted the flexibility to be able to go anywhere in the world if we wanted. Five years later, we are on the outer edge of the Great Barrier Reef in Australia with dreams of ranging still further afield.

One notable test of Dirona’s strength and systems happened recently during an attempt to cross the Wide Bay Bar south of Fraser Island on the east coast of Australia.

River bars can be dangerous and anyone with sea experience knows to avoid them if the conditions aren’t right. However, estimating when the conditions aren’t right isn’t as straightforward as one might think.
 
Before approaching the Wide Bay Bar, we read all we could on the bar crossing and what to expect. We radioed Australian Coast Guard at Tin Can Bay to get the latest GPS coordinates since bar conditions can change over time. Coast Guard watchstanders said nobody had crossed that day, but they did expect it would be rough and speculated it must be rough out where we were as well. We agreed — it definitely was lumpy.

Dirona’s aft cockpit boarding door latch was sheared. 

James and Jennifer  Hamilton

At this point, we felt like we had all the information available on the bar crossing as we approached it from seaward. There are two aspects to sizing up bar condition from sea that make precision difficult. One is that turning around and returning to sea can be difficult; the other is that the backsides of waves driving onto the shallows always look much smaller than they do when looking from the landward side.

A good data point is to watch the waves amidships and just forward of amidships. These were towering waves breaking just 50 feet to the right and left of Dirona. But, as we slowly inched into the shallows, there were no breaking waves across the over 100-foot-wide entrance path. The waves were big and the water was incredibly churned up further in, but the line of breaking waves had a clear gap. 

Heading straight in
We kept the boat centered on the entrance path and continued to look both forward and back as we proceeded shoreward. A particularly large wave was building behind us. A major concern was that the non-breaking section behind us was closing up on this wave and starting to break all the way across. Because we were traveling in the same direction as the wave, there was actually more time than you’d expect to watch the non-breaking gap close up behind the boat. The wave just kept climbing as it neared us, lifting Dirona. We raised about a third of the way up the wave as it passed underneath before getting hammered by the break from above. Waterpower is simply incredible.

Dirona was driven back down the wave by the breaking section. As we headed down, the stern gradually accelerated more quickly than the bow and started to swing off course to the right. We now were at full throttle and full right rudder, but the stern continued to get driven around the forefoot towards the starboard side.
 
The boat rotated broadside into the wave, the wave continued to drive it down and the boat slowly rolled away from the wave. At this point we could hear the furniture “pouring” into the starboard side of the boat. We didn’t really feel that far heeled over, but gravity definitely was creating a mess in the salon behind us. When the wave had passed, the boat popped up but the wave’s twin was close behind and also breaking. We turned the boat back towards the shoreward path we were on earlier as the second wave hit hard from above.

Dirona’s engine air intakes are four or five feet above the waterline and set to the inside of the boat, preventing downflooding when the wave came aboard. 

James and Jennifer Hamilton

As the second wave passed, we were fully upright and back on course. I was pretty confident we could continue through the random choppy seas forward and safely make it through the channel. It appeared we had seen the worst. But, there were now alarms going off all over the place inside the boat. Forward still looked better than backward at this point, so I quickly checked both the main and wing engines — both were fine. I briefly thought we’d lost steering, but it was just the steering follow-up lever and the steering was fine as well. All mechanical systems were okay and, as I scanned the instrument panel to figure out where the alarms were all coming from, I told Jennifer that I believed we were okay to head in with no further breaking waves appearing.

Multiple alarms
We could now see that we had many bilge water alarms firing, and I knew the autopilot follow-up lever was no longer working. We have an old rule that has stood us well over the years: If in a difficult or dangerous situation and a systems fault occurs, abort the trip and find a safe spot to correct the issues. The logic here is that most disasters are not a single mechanical or human fault. More often than not, life or property is lost when a chain of failures happen where each builds on the other. So, very reluctantly, I swung the wheel hard over and used the thrusters to rotate the boat 180 degrees and put the bow back into the seas before the next wave hit.

Understanding the source of the alarms, ensuring mechanical systems were good, and making a decision to leave felt like it was a fairly long process, but it was actually only the tiny space between the second and third breaking wave. The third wave broke as we rode slowly up to the top, crested, and then fell deep into the trough beyond. The boat felt perhaps a bit lethargic but with the waves on the bow, there wasn’t much of a concern.

I also had the hydraulic emergency bilge pump on, since both the high water and the main bilge pumps had run flat out since the knockdown. By now, I’d accepted all the alarms, there was finally quiet, and things had settled down.

The boat now felt fairly secure as we took the fourth breaking wave without issue, and the next one looked smaller, either because the over-large set had passed or we were getting more depth under us. So, I left Jennifer with the helm and ran down to the engine room to check on the bilge alarms. The bilge was completely full and the water was about six inches above the engine room floor and about two inches up onto the bottom of the main engine oil pan — not good. I was starting to worry about where it all was coming from and whether we might have an even bigger problem. I ran back up to the pilothouse to check on the situation and then went back down to the engine room. 

Dirona’s satellite compass system recorded a 69.1-degree  roll after being struck by the wave.

 James and Jennifer Hamilton

The water was now down below the floorboards, leaving behind a surprisingly large amount of dirt and organic matter. The main bilge was now close to dry, but the forward bilge drain into the main bilge was plugged with debris and there wasn’t a dent in the forward bilge water levels. I cleaned out the drain and the water flowed down in seconds and was ejected just about instantly by the hungry hydraulic emergency bilge pump.

The boat now was fully dewatered by the hydraulic bilge pump. It’s an absolute beast, able to pump hundreds of gallons per minute. I have always loved this piece of safety equipment, but my fondness for it grew considerably over those few minutes. It was just wonderful to see the water level falling.

The boat was now back at 100 percent operational. There was no water in the engine room or the bilge, and even the “failed” steering follow-up lever was back and fully operational. Apparently the follow-up lever always was fine, but the aft helm station had “taken control” during the knockdown, probably due to seawater closing the “take control” switch contact momentarily. We ran the short distance to the Double Island Point anchorage where we took a safe spot, cleaned up the boat and inventoried the damage.

Knocked over nearly 70 degrees
In taking stock of the situation, we were surprised to learn that our sat compass system had measured the boat heeled over at 69.1 degrees. It really didn’t feel like that much. Dirona has never —even in the worst conditions — been heeled over more than 30 degrees. Because the waves were breaking from so far above Dirona, we took stresses all over the boat:
• The dinghy was held down by heavy-duty trailer straps, and the nylon strapping on one had parted, so the dinghy had shifted in its chocks. Our aft deck furniture was folded up and attached to the starboard side of the cockpit with the same type of trailer straps, and one was stretched so far that the stainless steel latch no longer closed.
• The hydraulic pressure was so high in the cockpit and starboard walkway that the forward deck boarding hatch barrel bolt was bent outwards and was no longer operative.
• Even more surprising, the aft cockpit boarding door latch had completely sheared. Apparently when the door blew open, it then latched open. Later, hydraulic pressures tore that latch out as well.
• Two of the five LED strip lights along the starboard walkway were destroyed by the water pressure. The two overhead lights in the walkway filled with saltwater and failed quickly from corrosion. 
It’s unlikely, given the location of the engine intake grills (four or five feet above the waterline and set to the inside of the boat), that they were ever underwater. But, we still managed to take on hundreds of gallons from the onboarding wave through the starboard intake grill. The two engine-room cooling fans on the starboard side failed a day later due to seawater ingress but, throughout all this stress, everything kept working during the time of the event.

Dirona’s engine room experienced flooding approximately six inches above the engine room floor. 

James and Jennifer Hamilton

More than anything, this experience drives home the point that can’t be made often enough: If water doesn’t get into the boat in large quantities, you can survive incredibly bad conditions. And even safe conditions can be life-threatening if water gets into the boat. Many fishing boats have been lost to a broken pipe underwater causing flooding, or a pilothouse door opening as the boat gets hit by a large wave.

On Dirona, we have a policy of having the boat sealed up without windows or doors open when operating in difficult conditions no matter how hot it is. If doors were open in this event, the boat clearly may have been lost. That’s the same reason we use the storm plates to protect the larger windows on longer crossings. A broken window can sink a boat in difficult conditions. We did take in hundreds of gallons through the engine room air intakes but I’m not sure how I would recommend designing them better. What I like is that the water was kept away from the equipment and was quickly ejected by the emergency bilge pumps, making large-capacity dewatering pumps is a worthy addition to any boat. 

See more at James & Jennifer Hamilton’s website: blog.mvdirona.com.

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