Current location Auto-update
View larger map
Loading map ...

Recent log entries

View more on large map

 Sunday, November 16, 2014

View from Mt Oldfield, Lindeman Island

From the southern Great Barrier Reef, we continued north to one of Australia's premier cruising grounds, the Whitsunday Islands. Roughly 500 miles north of Brisbane, the Whitsundays are a group of 74 islands spread over 100 miles. Most of the islands are national park, with a half-dozen or so resorts sprinkled throughout. Offshore, the outer reefs of the Great Barrier Reef are only 20 miles away.

We spent the first half of our Whitsunday visit in the islands themselves. The anchorages were excellent and we particularly enjoyed the many view hikes. The panorama at the top of this post was taken from Mt. Oldfield on Lindeman Island, and the one below is looking north from Whitsunday Peak on Whitsunday Island.

The Whitsundays also are famous for their beautiful beaches, the standout being Whitehaven Beach, a three-mile long silica-sand beach on the southeast corner of Whitsunday Island. The incredibly soft, white-sand beach stretches all around the bay, with multi-hued blue waters offshore. And a short track from the beach leads to a viewpoint with sweeping views. Whitehaven Beach is so popular that floatplanes and even helicopters make regular trips there.



We finished our Whitsundays trip in the outer reefs and had a fantastic time there. As with the Swain Reefs farther south, the outer reefs are landless and poorly charted, with few other boats. In the busy Whitsunday Islands we almost always shared an anchorage, but rarely saw another boat in the outer reefs. Unlike the Swains, the water temperature was over 80F, and we could ditch the cumbersome drysuits for our 3mm wetsuits. The visibility also was better, and the coral and fish life was excellent. We'd heard that reef life isn't nearly as good as it used to be, but we certainly weren't disappointed.



Click the travel log icon on the left to see these locations and more on a map, with the complete log of our cruise through the Whitsundays. 100 Magic Miles is an excellent cruising guide for this area, with detailed anchorage and hiking maps. Alan Lucas' Cruising the Coral Coast was helpful as well.

On the map page, clicking on a camera or text icon will display a picture and/or log entry for that location, and clicking on the smaller icons along the route will display latitude, longitude and other navigation data for that location. And a live map of our current route and most recent log entries always is available at
Sunday, November 16, 2014 1:01:43 PM (Pacific Standard Time, UTC-08:00)  #    Comments [2] - Trackback
On the Water
 Sunday, November 02, 2014

In 2012, we were fortunate to be in San Francisco during America's Cup season. We watched an AC45 World Series race live, and not long before, saw the open-water debut of Oracle Team USA's AC72.

While in Gosford, Australia we met Gosford Sailing Club director David Slingsby, who invited us in for a post-race drink after the club's Saturday racing event. We had a great time chatting with the group about sailboat racing and our trip across the South Pacific. David offered us the opportunity to meet the defending America's Cup champions, Oracle Team USA, who were at nearby Lake Macquarie for Foiling Camp focusing on hydrofoil sailing skills using Moth class boats. David's son Tom Slingsby is Oracle Team USA's helmsman, strategist and sailing team manager.

When we arrived at Lake Macquarie, the team was tuning and fixing their rigging following the previous day's training. In the rightmost picture below, Tom Slingsby is splicing a line on his Moth. Also attending were Joshua McKnight, the current Moth world champion; Tom Burton, the top-ranked Laser sailor in the world; Andrew McDougall, a multiple-time Australian Moth racing champion who has several times placed second in the Moth world championships; and David's son-in-law Joel Castle, who we'd watched Moth-sailing at Gosford and who also has raced competitively internationally.

Andrew McDougall is the designer of the Mach 2s that dominate Moth racing. He was at the camp to provide training on hydrofoil rig setup and sailing technique. In the leftmost photo below, Andrew is wearing the black T-shirt, and David Slingsby is standing between Andrew and Jennifer.

It's rare to meet a group like this who are at the top in their field. Everyone was focused, but quite friendly, and willing to answer questions as we watched them work. Thank you David for bringing us along, and Tom for allowing us to attend. It was a real highlight of our trip.

Sunday, November 02, 2014 1:44:26 PM (Pacific Standard Time, UTC-08:00)  #    Comments [0] - Trackback

 Wednesday, October 01, 2014

One of the reasons we started diving over fiften years ago was getting full value from one day visiting the Great Barrier Reef. Even twenty years ago, we knew we were coming, we just didn't know when. We finally arrived. Our first dive was at Lady Elliott Island, the southernmost reef in the chain that makes up the Great Barrier Reef. We had a great dive--visibility was excellent, the coral life was good, and we saw a white-tip reef shark, a turtle, a huge wrasse, and many other fish of all sizes. The highlight of the dive was Lady Elliot's famous Blow Hole--a 20'-diameter swim-through lined with coral and packed with fish. From Lady Elliot Island, we worked north to Lady Musgrave Island, Fitzroy Reef and Heron Island before running east to the Swain Reefs, the southernmost of the outer reefs.

Lady Elliott and Heron Islands were the only anchorages where we didn’t navigate inside a coral reef. Anchored in the turquoise waters of the reef lagoons felt just like being back in the Tuamotus in French Polynesia, and Beveridge Reef in the central South Pacific. The visibility through the water isn't quite as good, but it's the closest we've seen.


Lady Musgrave Island (below left) and Fitzroy Reef (below right) had marked entries that were narrow, but reasonably easy to follow, and a fair number of boats at each. The Swain Reefs are more remote—we never once shared an anchorage and saw only a handful of other boats the entire week we were there.


The reef entries in the Swains were quite narrow, with no marked channels. We navigated to these narrow, unmarked channels using a combination of the chartplotter and a tablet app that shows our position on the satellite imagery. Both C-Map and Navionics charts show only a rough approximation of the reefs and their location. The satellite imagery often was more helpful.


In these tight spots, visibility is key since there is no chart detail and, even if there was, counting on GPS accuracy down to ten feet is not safe. We run with Jennifer on the bow and James at flybridge, both wearing polarized sun glasses. We carefully maintain a safe exit plan at all times, and then go slow and discuss every detail. We prefer to enter when the sun is over-head, or somewhat behind, to avoid glare and have the best visibility to underwater hazards. If you do enter with the sun behind, you have to be extra careful to keep track of where you are in case conditions are unsatisfactory inside. If you have to leave, you'd be going into the sun and glare.

Managing the boat is harder in significant wind but, even before that becomes a problem, the chop in the water makes it hard to resolve depths. So these operations need to be done in favorable wind conditions. We creep in slowly, have the thrusters ready--which are fairly effective at very low speeds, and don't commit to an entry until we are convinced we have full control and like the conditions. The photo sequence in the video below shows us navigating into Frigate Lagoon in the Swain Reefs.

None of the reefs we anchored at in the Swains had any land, but the reefs themselves provided reasonably good swell protection. We loved the wildness and remoteness of the Swain Reefs and had a great time exploring by dinghy and also did several excellent dives there. The first video below was taken at Sanctuary Reef. The seascape there was surprisingly complex, with narrow swim-through channels lined with coral. The second video is our favourite Swain Reefs dive at Horseshoe Reef. We started out swimming through coral channels encrusted with hard coral, swam over a forest of staghorn coral, and then worked along a 60-foot wall layered with coral.

Click the travel log icon on the left to see these locations and more on a map, with the complete log of our cruise through the southern Great Barrier Reef.

On the map page, clicking on a camera or text icon will display a picture and/or log entry for that location, and clicking on the smaller icons along the route will display latitude, longitude and other navigation data for that location. And a live map of our current route and most recent log entries always is available at

Wednesday, October 01, 2014 2:11:05 PM (Pacific Standard Time, UTC-08:00)  #    Comments [2] - Trackback
On the Water
 Tuesday, September 16, 2014


We bought an ocean-capable boat not because we were convinced we would round the world, but because we wanted the flexibility to be able to go anywhere in the world if we wanted to. We bought a strong boat not because we were convinced we needed to test it, but because we wanted a boat with "engineering headroom" -- we wanted it to be considerably stronger than the worst we were likely to ask it to operate through.

Five years later, it turns out it's a good thing we decided to accept the various compromises that come with an ocean-capable power boat. Who would have guessed that, as we type this, we're anchored on the outer edge of the Great Barrier Reef in Australia with dreams of still ranging further afield. And, looking at the other attribute we value so greatly, boat strength, it's not one we expected to test and it's certainly not one you want to test. But Dirona has done fairly well by that measure as well. We have seen no survival storms -- fortunately they are rare and modern weather reporting can avoid the worst of them except in statistically anomalous situations. But they can happen, so we wouldn't sacrifice strength for anything. Just two people out in the ocean 1,000 miles from any shore can make boat strength feel like a super important attribute even though it is seldom tested.

We have seen some tough weather but most of it was actually surprising close to shore. Ironically most boat operators are extra-careful in selecting the weather and time of year when making ocean crossings so it's little surprise that the worst conditions experienced by recreational boats are often near to shore. For us, memorable times are fully developed seas in 40 kt wind in the Gulf of Alaska with gusts as high as 59, the east coast of New Zealand north of Wellington in only 30 to 40 kts, and the east coast of Australia in the shallow coastal waters of the Tasman Sea near Brisbane in around 40 kts. None of these conditions were particular dangerous or even scary but they were onerous and sometimes a bit tiring. Having a good strong boat can transform the potentially scary to only tiring. And, there is no question, compared to the stories you hear from local fisherman and professional mariners that are out there all the time in these areas, we have seen close to nothing on board Dirona.

One notable test of the boat did happen fairly recently in attempting to cross the Wide Bay Bar south of Fraser Island on the east coast of Australia. In all the conditions we had seen prior to this event, we have managed to avoid large breaking seas. It's in these conditions where weather conditions swing from taxing to dangerous. Massive breaking seas can happen in extreme conditions, but are especially frequent where high winds meet large ocean currents (e.g. the Agulhas Current near South Africa). Fortunately, these conditions are fairly rare and largely avoidable. One place where these conditions are actually fairly common are river bar entrances. In the US, the entrance bar of the Columbia River is particularly renowned for producing harrowing conditions -- in fact, the US Coast guard trains rough water small boat handling there -- but nearly every maritime country has their example. In New Zealand, the Grey River Bar has really earned its notoriety.

River bars can be dangerous and anyone with sea experience knows to avoid them if the conditions aren't right. But, estimating when the conditions aren't right isn't as straight forward as one might think. For example, we crossed the Columbia River bar where, just 1 hour before, the US Coast Guard had it closed to all recreational craft. At the time when we actually crossed, they were only allowing boats through that were over 50'. We braced for difficult conditions but actually found it an unremarkable crossing.

Recently, when faced with the same decision here in Australia, it was clear that conditions were worse than our Columbia River bar crossing, but with the wind blowing a steady 30 to 40 kts and it being nearly 100nm to another anchorage, there is a clear appeal to crossing the bar. The conditions were not expected to improve for 3 days. Nonetheless, we'll take 100 nm in rough water over dangerous conditions all day, any day. Before approaching the Wide Bay Bar, we read all we could on the bar crossing and what to expect. We radioed Coast Guard Tin Can Bay to get the latest GPS coordinates since bar conditions can change over time and the Coast Guard often has current bar conditions. They said nobody has crossed that day but they did expect it would be rough and speculated it must be rough out where we are as well. We agreed, it definitely was lumpy. They said we might be happier in than out but neither would be easy right now.

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 turning around and returning to sea can be difficult and the other is the back side 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 beside and just forward of beside the boat. These were towering breaking waves off just 50' to the right and the same to the left of Dirona. But as we slowly inched into the shallows, there were no breaking waves across the 100'+ entrance path. The waves were big, the water was incredibly churned up further in, but the line of breaking waves had a clear gap along the entrance path. Our read of the conditions were that they were difficult but crossable and we proceeded further in. We were watching behind us as much as in front as we followed the recommended crossing path. Conditions ahead continue to look random and churned up and the waves beside us were breaking and dangerous, but we continued to work in on large but not particularly frightening waves. We keep the boat centered on the entrance path and continud to look both forward and back as we proceed shoreward. A particularly large wave was building behind us and it seems to just keep getting bigger. What was a big concern is the non-breaking section behind us was closing up on this wave and it's starting to break all the way across. Because we are traveling in the same direction as the wave, there is actually more time than you would guess to watch the non-breaking gap close up behind the boat. The wave just kept climbing as it neared us, starting to lift Dirona at the base of the wave. We rose about 1/3 of the way up the wave as it passed underneath before getting hammered by the break from above. Water power is simply incredible.

Dirona was driven back down the wave by the breaking section fast and, as we headed down, the stern very slowly 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 by the breaking wave from above. 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 was popping 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.

As the second wave passed, we are 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. Essentially, we're back upright, on the right track to proceed, and it appears we have 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. I quickly checked both the main and wing engines and both were fine. I briefly though I’d I've lost steering but it was just the steering follow-up lever and the steering was fine as well. All mechanical systems were OK and, as I scanned the instrument panel to figure out where the alarms are all coming from, I said to Jennifer I think we're OK to head in with no further breaking waves appearing to be forward. We could now see that we have many bilge water alarms firing, and I knew the auto-pilot follow-up lever was no longer working. We have an old rule that has stood us well over the years: "if in 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 one hit.

Understanding the source of the alarms, ensuring mechanical systems 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, these waves were not really 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 to something closer to normal. I looked down into the salon from the pilot house and the furniture was piled up in the forward, starboard corner of the salon up against the day head. Clearly there would be some damage down there.

The boat now felt fairly secure as we took the 4th 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 6" above the engine room floor and about 2" 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 pilot house to make sure all continued to be well. It was, so I went back down to the engine room and the water. The water was now down below the floor boards, leaving behind a surprisingly large amount of dirt and organic matter. I ran back up the pilot house to find things still under control, and back down to the engine room. The main bilge was now close to dry but the forward bilge drain into the main bilge was plugged with sea-born debris and wasn't making much of a dent in the forward bilge water levels. I cleaned out the drain from the forward bilge down into main bilge, 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 and is able to pump 100s of gallons per minute. In testing, it can send a 2" jet of water across two slips! It can pump a silly amount of water. 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, proving it's either not a problem or, if it is a problem, the safety equipment had the clear upper hand.

The boat was now back to 100% 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 sea water closing the "take control" switch contact momentarily. We ran the short distance to the Double Island Point anchorage where we joined three other boats attempting to wait out the worst of the storm. We took a safe spot in the anchorage and cleaned up the boat and inventoried the damage.

In taking stock of the situation, we were surprised to learn that our sat compass system had measured the boat over at 69.1 degrees. It really didn't feel like that much. And, I suppose, for the old sailing hands out there it really wasn't all that much -- many have seen a knockdown or two. But, as a point of reference, Dirona has never, even in the worst conditions, been heeled over more than 30 degrees so it seems like an awful long way over to us. Because the waves were breaking from so far above Dirona, we took stresses all over the boat.

The dinghy is held down by heavy-duty trailer straps, and the nylon strapping on one had parted and 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. One was stretched so far, 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 no longer operative.


Even more surprising, the aft cockpit boarding door latch had completely sheared.  The first picture below shows the broken latch, and the second picture is after we replaced it.


Apparently when the door blew open, it then latched open. Then 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. And the two overhead lights in the walkway filled with saltwater and failed quickly from corrosion.  


The galley flower vase, stowed in a port-side basket behind the salon furniture, shattered as it hit the starboard-side settee. And one drinking glass broke. There are three sets of scratches on the woodwork in the salon from furniture in flight. I hate seeing a blemish or two in Dirona's woodwork but, in the end, I suppose it’s nice be surveying minor cosmetic damage. There really wasn't much damage at all.


It’s unlikely, given the location of the engine intake grills (4 or 5 feet above the waterline and set to the inside of the boat in first picture below), that it was 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 sea water ingress but, throughout all this stress, everything kept working during the time of the event.


The boat popped up like a cork as soon as released by the breaking wave, everything kept running, the safety equipment did what it was supposed to do, and as soon as we were bow to the waves again, it wasn't even particularly difficult to manage even with breaking waves. The list of faults we did take is not insignificant but it feels like a bunch of minor scrapes and nicks.

We feel like the boat did really well and, as we reflect on the situation, the first things that jumps to mind is we are glad we got a strong boat. Money spent on strength sure feels well spent and giving up speed or interior space for strength feels like a bargain. The next things is that breaking waves can happen anywhere and are in no way restricted to bar conditions. Bar crossings produce them with frequency but breaking seas can be found across a wide set of different circumstances. The obvious learning is to avoid them but there may be times when you do find these conditions. Knowing how the boat manages them is important. For Dirona, the boat seems most comfortable bow into the weather in survival conditions so, if we ever do find ourselves in breaking seas in the open ocean, we will get the bow into the waves to ride it out. Looking specifically at river bars where these conditions are common, we have long known that waves appear smaller from the backside than from the landward side. So it's important to keep this in mind when assessing conditions. It's difficult to turn around fast enough in a narrow channel between big waves so it’s important to make the decision early enough. And, what we learned in this case arguably we already knew but this certainly drives it home, wave sets vary greatly in size. If there is a respectable period of non-breaking water in a channel, it doesn't mean that you won't find a larger set of waves when transiting. We would have been well served by studying this entrance for longer from seaward since breaking seas can be so dangerous.

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, unfortunately, even very safe conditions can be life threatening if water does get into the boat. I'm an engineer at and I read extensively about engineering disasters mostly because it's my job to avoid them. Knowing how others fail can help me build systems less likely to suffer the same fault. I do the same thing around boating and read extensively about boat losses and faults. It’s absolutely amazing how many fish boats have been lost to a broken pipe underwater causing flooding, or a house door left open as the trawl door pulls the boat over, or a pilot house door open as the boat gets hit by a particularly 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 100s of gallons through the engine room air intakes but I'm not sure how I would recommend designing them better. They are very well placed on Dirona and I've had many a fisherman look longingly at our engine room intakes commenting they like the placement and height. I'm not sure how to avoid the few seconds of water ingress we did get. What I like is the water was kept away from the equipment and was quickly ejected by the emergency bilge pumps. Having silly large capacity dewatering pumps is a worthy addition to any boat. On Dirona, we have all the standard pumps, and Nordhavn is quite generous in this dimension, and we also have the optional hydraulic bilge pump and a portable Honda crash pump that does double duty as an emergency dewatering pump and fire pump.

Another policy we have, that certainly limited the damaged we sustained, is that the boat is always ready to go to sea. The few large loose items we have, such as the deck furniture, are easily stowed. We have heavy-duty latches on all appliance doors and any heavy drawers—the small push-button latches are fine for moderate conditions, but will not hold in rough seas. When we heeled over at the Wide Bay Bar, several minor items on the port-side guest stateroom berth were launched to the desk on the starboard side, skipping the floor entirely. If we didn’t have the heavy-duty latches on the large, heavy drawers underneath the berth (second picture below) those drawers would certainly have been ejected, resulting in considerable damage.


After a night in a rough anchorage with 3 other boats to sit out the storm, we woke the next day to find our 1" anchor chain snubber with ballistic nylon anti-chafe had parted in the over 50 kt gusts. But it was likely the 3' to 4' swell rolling through the anchorage that loaded the snubber to the point of failure. That morning at high tide, we went back to survey the bar conditions. There was no question they were better than they were the day earlier but, with breaks very near the channel and fairly big water across the channel, we elected to do the 100+ nm run around the north end of Fraser Island.


The Fraser Island and Great Sandy Straits area really is an amazing cruising ground and we really enjoyed our time there. One particularly interesting day, we were anchored for the night just inside the Wide Bay Bar and walked over to the other side to watch the waves pound in from seaward. Over a nice picnic lunch on a windy but sunny day, we remarked how much bigger the waves look from the shoreward side. It was exciting to watch them crash in over lunch.


Tuesday, September 16, 2014 3:04:18 PM (Pacific Standard Time, UTC-08:00)  #    Comments [10] - Trackback
Nordhavn | On the Water
 Friday, August 22, 2014

A little over a year ago, we worked our way south from Fanning Island, Kiribati towards Nuku Hiva in the Marquesas Islands. We were on a long, fuel-constrained run where we would cover 2,600 nm without fueling. For most of the trip, we were heading up-current and into 30 kts of wind on the bow. The waves were fairly well-developed and spray filled the air day after day. The outside temperature was well over 80F, and the master stateroom was 88F, which made sleeping more difficult. With the doors open for ventilation, a thin layer of airborne salt soon covered the boat interior. But we were not crazy about closing the boat up and running the air-conditioning, because that consumes more fuel and would be a couple of weeks of generator run time at very low load.

As we neared Nuku Hiva, we concluded that we had far more fuel than we were going to use, so we might as well be comfortable and run the air conditioning. I'm not crazy about extended run times on the generator at under 20% load, but it'll live with it, and it was so wonderful and relaxing to finish the last few days of the crossing sleeping well in air-conditioned comfort. This convinced us we needed to find a way to air-condition the boat underway without running the generator.

In the Tuamotus, we were diving daily and just loving it. It's just amazing to look up from 140' down and be able to clearly make out our dinghy floating above us and then look down and see 150' down to the ocean floor and be surrounded by beautiful fish, sharks swimming by, and a sea turtle making a pass through the area. It was incredibly beautiful, but we found ourselves wondering what would happen if our generator failed. Without the generator, we can’t fill SCUBA tanks, can't make water, and can’t use the washer, dryer or oven. The inability to make water when that far "out there" is not at all appealing. Our goal is to never have a trip ended early or be redirected by a fault and it would be very difficult to get generator parts flown into some of the obscure, uninhabited islands we visited on this trip. We needed a backup to the generator, but really have no space for another generator on Dirona.


As we continued across the South Pacific we spent the vast majority of the time on anchor. But when we did go to a marina, the shore power was rarely better than 15A. Some of those 15A connections could only reliably deliver 12A without the breaker triggering, and in some places the shore power capacity was over-taxed by the visiting boats and, consequently was sagging badly. Also, they were often 50-cycle connections and Dirona is a 60hz boat, so we couldn’t run most 240v appliances without running the generator. We really felt we needed some way to draw what the shore power had to offer, but to not trigger a breaker and not have to manage the boat to a consumption of less than 15A. Both Atlas and ASEA offer shore power frequency converters that would handle the cycle difference, but they are expensive—friends have spent as much as $50,000 on shore power conversions—and they still don't allow running the boat well at over 25A while drawing under 15A on the shore power connection. The frequency converters didn't look like a good solution for the entire problem.


After many nights of thinking through options on passage, and planning and drawing up different solutions during the day, we came up with a solution that appears to solve all the problems outlined above. We installed the new design when we arrived in Whangarei, New Zealand and, having used it for the last year, it really does seem to nail every requirement listed above and a few more. Summarizing what the system delivers:

Backup generator: If our generator fails, we need to be able to operate all 240V appliances including the water maker and SCUBA compressor and produce up to 8kw of power, without installing a second generator. This is super important were the main generator to fail (it never has), and is also very useful for quick 240V loads like running the oven for 10 min without bothering to start the generator.

Efficient light 240v loads: Light 240v loads, such as running a single HVAC while underway, is not an efficient use of the generator. While light loads generally aren’t ideal, our bigger concern is that running the generator 24x7 increases the maintenance frequency. Changing the oil and filter every 10 days is not where we want to be.

50hz/60hz invariant: We have a 60 Hz boat, but more often than not are plugged into 50Hz power. We needed to be able to connect to 50hz or 60hz and run all appliances without restriction and not have to start the generator.

Very low amperage shore power invariant: We want to be able run all appliances regardless of draw without any restriction, without having to run the generator, and with only a single shore power connection that might be as small as 10A at 240V or 20A at 120V. Boats are getting bigger and better equipped all the time and many marina shore power systems are not up to the draw they are asked to deliver. It's not unusual to see shore power voltage drop down 20% below nominal line voltages. Voltage sags can damage equipment, so we needed isolation ensure that our equipment gets clean, voltage stable power even when the shore-side system is sagging under the collective load.

110v failover: If the 110v inverter fails and we’re not connected to 60hz shore power, we must start the generator to get 110v power. We wanted a backup for a 110v inverter failure without plugging in or starting the generator.

Battery protection for shore power loss: A big concern when leaving a boat unattended at a marina is the shore power could get disconnected, unplugged, the breaker may trip, or a variety of other mishaps could leave the boat unpowered and drain the house batteries. This is bad for the batteries and might result in other problems such as spoiled freezer food. We want the system to ride through a shore power fault by failing over to the generator, running it if needed to save the batteries, and return automatically to shore power if it comes back.

I'll start with the equipment we installed and how the different components work together to solve the requirements we have itemized above.

1) Install 240V, 60Hz Inverter: This is the most important part of the design. Install a sufficiently large inverter system such that all appliances in the boat can be run off the inverter. On Dirona, we have a 4kw inverter to feed the 110V appliances, so 6kw is sufficient to support the 240V equipment we have on board. In our case, we installed 2 paralleled Victron 3kw 110V inverters to achieve 6kw of 240V power. We particularly like this inverter choice because they are simple and don't include a charger—all they can do is invert—and are capable of delivering far more than their specification. The inverters are specified to deliver 6kw at 240V, which is roughly 25A, but they can deliver peak loads over 50A and can operate for extended periods at or even beyond their rated output without sag, over-temperature, or cutting out. They are tanks, and just keep delivering no matter what. I'm amazed to report they can start the SCUBA compressor, where the required inrush current at startup can exceed 50A. After a year of use, we just love these units. The key to making this design work is to ensure that the inverter capacity is sufficient to run the boat without restriction, using whatever combination of 240v equipment you need. So, if you chose to duplicate this design, ensure you have adequate inverter capacity. 6kw is enough for us but you can get 240V inverters in a variety of sizes up to 20kw.



2) Upgrade Ships Service Selector Switch: The Ships Service Selector switch as delivered on Dirona (leftmost of the three in the first picture below) allows the operator to feed the 240V breaker panel from either shore power or the generator. We replaced this switch with one supporting a 3rd input (2nd from left in the second picture below) so we can feed the 240V panel and all 240V appliances on the boat from 1) shore, 2) generator, or 3) inverter. This third position runs the entire house system off the new 240V inverter.


3) Install Battery Charger Selector Switch: As delivered, the battery chargers on Dirona draw power from the 240v panel. In other words, one of the 240V "appliances" are the two battery chargers. It would be a very bad configuration indeed to be running the 240V appliances off the inverter and have the battery chargers taking power from the inverter, using it to charge the batteries, which are then feeding the inverter. To support many of the use cases above, the chargers must be powered separately from the 240V panel. We want, for example, the 240V panel to be running off the inverter while the chargers are running off shore power. So we separated the battery chargers from the 240v panel and added a Charger Service Switch (leftmost of the four in the second picture above) to supply the chargers from either shore power or the generator.

An electrical diagram showing these first three modifications is below.

4) Upgrade Start Battery Alternator: The final component upgrade to complete the system is replacing the 85A start battery charger with a 190A @ 24V alternator and installing heavier cabling for this larger alternator. The house battery bank already has a 190A @ 24V alternator so, in this new configuration, we have two 190A @ 24V alternators on the main engine. With the two alternators in aggregate, we have 9kw of power generation on the main engine. But, you probably wonder why we would ever want a 190A charger on the start battery system. The original 85A alternator was arguably already far more than would ever be required. Well, it turns out that bigger is not really a problem in that a large alternator with a high quality smart regulator can produce whatever the start batteries need regardless of how low. So, having an extra-large alternator does no harm but is unnecessary. When this second large alternator becomes very useful is when we parallel the house and start alternators onto the house battery bank. In that configuration, we can produce over 9kw of charging for the house battery bank. In our standard configuration, with only a single house battery bank alternator, we have 4.5 kw of power available all the time. We can run air conditioning units, the water maker, and charge the batteries. If we need more power, we can parallel in the start alternator and have 9kw available. This is useful if we have a generator failure but there are times when it's nice to be able to charge the batteries at 300A for an extra fast charge and still be able to run the water maker or air conditioning system.


To make it easy to parallel in the start alternator when needed, we mounted a switch and warning light on the dash that closes a 200A continuous duty relay to make the second alternator available to supply the load when needed by just flipping a switch.


With these four sets of new components and changes installed, we can solve all the problems we outlined above by combining these components in different ways. Repeating the requirements list above, we'll see how each is solved.

Backup generator: The combination of the 6kw 240V inverter and the 9kw of main engine charging capability allows us to have a backup generator without giving up the space. Generators are reliable and we have never experienced a disabling fault, so it's hard to justify giving up the space for a second generator in a small boat. If we do end up needing the backup, the hours on our main will go up marginally, but the trip will be saved. It's nice to not give up space for a second generator and yet still have the redundancy protection that comes from one.

Efficient light 240v loads: There are times when you’d like to run the oven for just 10 minutes, but it's just not worth starting the generator for such a short period. The 240V inverter is happy to deliver the power and although the battery draw is high, it's short enough that it doesn't really consume that much power. It's a nice efficient way to deliver the power for short periods without having to start the generator. Another usage model is low loads when underway. A single air conditioning unit draws less than 8A. It's not worth having the generator on 24x7 and having to change the oil every 10 days if you only need a small amount of power. The combination of the 6kw 240V inverter and the large on-engine alternators allows even fairly large 240V loads to be run any time without needing to start the generator.

50hz/60hz invariant: The combination of #1 (install 240V inverter), #2 (upgraded Ships Service Selector switch), and #3 (new Charger Service Selector switch) allows the boat to be run entirely on the 60hz inverter, while dual redundant 100A @ 24V Mastervolt ChargeMaster 24/100s charge the batteries. The Mastervolt chargers will run happily on either 50 cycle 60 cycles, so the batteries stay fully charged even on 50 cycle power while the boat continues to operate at full capability as a 60hz system. We never need to start the generator to use the oven or laundry for example. The combination of the chargers and the inverter can run any appliance at any time.

Very low amperage shore power invariant: Extending on the 50hz/60hz invariant point above, we can run on shore power connections as low as 10A at 240V or 15A at 110V even though our peak draw is often nearing 30A at 240V. Because the shore power is charging the batteries and the inverter is powering the house, instead of needing the shore power to provide the peak power requirements of the boat, we only need the average requirements. Often when a hair drier comes on and, say the water heater is already on, the sudden additional 8A draw will cause the shore power breaker to disengage. This is because the shore power is insufficient to meet the peak requirements of the boat. But, if running using the battery charger and inverter pair, as little as 10A is enough to power the boat even though our draws are often approaching 30A. Shore power only needs to supply average power draws rather than peaks. It's amazing what a relief it is to not have to manage loads, worry about what is running when, and not have to go out and reset the breaker multiple times each day. Suddenly shore power "just works." And there will be times when old shore power breakers can't deliver their rated output. I've often seen 16A breakers that will pop at anything over 12A. That's fine too. We just set the charger draw to what is available on shore and forget about it, knowing we will take what we need but never more than the shore power system can provide.

Shore sag invariant: The 240V power systems in many US and Canadian marinas is actually 208V. And, when overloaded the "240" can sag down below 200V, which can damage electrical appliances. With the combination of a 240V inverter powering the house and only the battery chargers connected to shore power, the boat always sees rock solid 240V power through the inverter, while the battery chargers deal with voltage sags and other shore power problems. The Mastervolt chargers will charge on just about any voltage and frequency in the world, so it all works without exposing the boat systems to sags, spikes and other shore power related anomalies.

110v failover: Our boat has both a 240V system and 110V system. The 110V system has a 4kw inverter and, if it fails, the only way to get 110V is to plug into 100v, 60Hz shore power or start the generator. With the 240V inverter, we can still get 110V anytime without running the generator via the 240V inverter. It feeds single phase 240V to the 240V system just as the generator would and the Nordhavn standard step down transformer will just keep producing nice, clean 110V output even if the 110V inverter fails. You might ask why bother with the 110V inverter at all? It could be eliminated without giving up any advantage described here but a larger 240V inverter would be required if we gave up the 4kw of 110V inverter. If we were doing a new build today, we probably would opt for a larger 240V inverter and omit the 110V inverter entirely.

Battery protection for shore power loss: Our battery selector switch (#3 above) has 3 input options: 1) shore, 2) generator, and 3) auto. Auto is an interesting configuration. In this mode, a large 120A continuously-rated relay is used to select between shore power and the generator. If shore power is available, the battery chargers are run from the shore power system. If the shore power system fails, is unplugged, a breaker pops or any other fault causes a loss of shore power, then this relay switches the battery charger source to generator.

Since the generator is not running, you might wonder what value there is in switching to the generator. Dirona is equipped with generator auto-start so, if the batteries are discharged to 50% capacity, the generator starts, the load is brought on after 2 minute warm-up, it charges the batteries back up, the load is removed for 1 min of cool down, and then the generator shuts off again. The auto-start system is a simple extension of the Northern Lights Wavenet system. The normal use of auto-start is to take care of the batteries and ensure they get charged when needed rather than when I remember. Jennifer and I are often late getting back to the boat after shore-side exploring. Rather than allow the batteries to discharge excessively, shortening their life, the generator just turns on and gets the job done without attention. Auto-start is a personal decision where each owner needs to weigh off the risk of running a generator without attention against the risk of allowing the batteries to discharge. Our take is well-maintained equipment works well and, just as most people wouldn't think twice of having their furnace kick on to prevent frozen pipes when they are not at home, we think auto-start is good for the boat. Even if you don't decide to install auto-start, the Northern Lights Wavenet system is strongly recommended. We love it.


The combination of the "auto" position on the Charger Selector Switch with generator auto-start/stop means that if something goes wrong with the shore power, the generator will start a day or so later, charge the batteries up, and then shut down and wait for when needed again. If the shore power comes back, it switches back to shore power and uses it again. We will also get email notification if the shore power gets disconnected and there are on-board alarms that signal this event but it's still good to have backup to protect the nearly $8,000 worth of batteries.

Even if we weren't cruising in 50hz countries, or remotely, where a generator failure would be difficult to deal with, we'd still install a 240v inverter. In fact, we've become so dependent on the system that we're considering getting a spare. In the past, we needed to run the generator underway or at anchor to make water, do laundry or for baking. We now only run the generator at anchor, either to charge the batteries or for extended large 240v loads. The 240v inverter and either shore power or the main engine can handle the rest. A shore power connection anywhere in the world is now effectively the same as if we were in the US, with the added advantage of isolation from low or sagging supplies. And having air conditioning while underway in hot weather is wonderful.

Thursday, August 21, 2014 11:30:24 PM (Pacific Standard Time, UTC-08:00)  #    Comments [18] - Trackback
Nordhavn | Ongoing

Our cruising guide, Waggoner sister publication Cruising the Secret Coast, is available at local bookstores and online. Click book image for details.

<December 2014>

Member Login
All Content © 2014, James & Jennifer Hamilton
Theme created by Christoph De Baene / Modified 2007.10.28 by James Hamilton / Modified 2011.09.17 by Jennifer Hamilton