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
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
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
The seascape there was surprisingly complex, with narrow swim-through channels lined with coral. The second video is our favourite Swain Reefs dive
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
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
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
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.
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
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
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.
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
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.
A little over a year ago, we worked our way south
Fanning Island, Kiribati towards Nuku Hiva in the
Marquesas Islands. We were on a long, fuel-contrained 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.
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
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:
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:
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
(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
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
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
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
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.
Our next-door neighbors, Mark Mohler and Christine Guo of Nordhavn 62
recently upgraded their davit to support hydraulic power-rotation. The base came off in two pieces, but
is much easier to put back together at the shop. The downside is a heavy assembly: the upgraded base, with the power rotation transmission and motor,
weighed just under 500 pounds. They'd need a crane to install their crane.
Our davit easily can lift the equipment, but doesn't have enough reach across the finger pier between the two boats.
Luckily, the slip on the other side of Gray Matter
was empty, so we backed Dirona around to put our stern adjacent to their bow with no finger pier in between.
With our davit fully extended, we were still a little short of reaching the mounting point on the centerline of Gray Matter's bow.
With some extra fenders in place, Mark carefully released his bow lines to inch the boats closer together.
Dirona has a KVH M7 satellite TV system installed. When we left Hawaii, we cancelled our satellite TV subscription with Dish Network and
haven't used the system since. We knew we had some work to do to get the system running outside the US, and it hadn't been a priority. It also wasn't
even a possibility until we got to New Zealand and in range of the television satellite there.
The only time we'd really missed it was for live sporting events.
We were in Fiordland
during the Superbowl and, with our 64kbps data connection,
we had trouble getting a reliable audio feed, let alone a video feed. We made do, and actually had a great time, "watching" the game over a mobile play-by-play
app. We're not sure if this was a step backwards to a time before television, or a step forwards,
but as Seahawks fans it definitely was among the most enjoyable Super Bowl we've ever watched.
Since we plan to be in Australia for over a year, getting the system functioning here felt worth the time investment.
The first stage was to climb the stack to replace the circular Low Noise Block (LNB) at the satellite television antenna with a
linear LNB. Circular LNBs are used in the US, Canada, Latin America and some parts of Asia. Linear LNBs are used in Mexico, Europe, Australia and New Zealand.
We had purchased a linear LNB when we bought the satellite TV system--this was among of the last few pieces of equipment that we carried for
worldwide cruising but had not yet used.
While up the stack, we also adjusted the skew angle on the LNB.
Periodically, in different parts of Australia, we'll need to repeat this adjustment. Circular LNBs don't require this adjustment, and newer M7
models can automatically adjust the linear LNB skew angle.
The next stage was to install an Australian digital receiver. The Australian government has established a free commercial satellite system: Viewer
Access Satellite Television (VAST), for viewers in remote locations or those who cannot receive terrestrial
services after the digital switch-over. Travelers, such as those in RVs or boats, also are eligible to use the system.
The satellite frequencies had changed since our system was delivered, so we needed to reprogram them into the satellite dish.
This allows the VAST receiver to find the satellite.
At this point in the process, we still couldn't display anything on our TV. The VAST receiver outputs a PAL-format video signal,
the standard used outside the Americas,
whereas all our AV equipment requires NTSC.
We ordered a Orei XD-1090
PAL-to-NTSC converter from Amazon with an expected delivery time of two to three weeks. While we waited for the converter,
Mark Mohler of N62 Gray Matter
next door lent us his PAL-format television so we could test our setup end-to-end. The receiver quickly found the
satellite and successfully established a connection.
With a single satellite to find, this stage was much faster than the Dish Network
satellite TV system we'd used in the US.
We've spent way too much time with the "Searching for Satellite" screen up as the Dish receiver
struggled to locate one of the multiple Dish satellites.
We soon had the system running end-to-end. Spitfire seemed to be particularly missing TV.
The last piece of the puzzle, an Orei XD-1090
finally arrived. And amazingly, it just worked. Equally amazing, Amazon shipped the
unit to Brisbane from the US in less than two weeks for only $8 shipping.
In summary, to get our US-installed satellite TV system working in Australia all we had to do was:
- Climb the stack and
- Swap the circular LNB for a linear LNB
- Manually adjust the LNB skew
- Program the new satellite frequencies into the dish
- Install a Australian digital decoder
- Install a PAL-to-NTSC converter.
Basically plug-and-play :).