New Inverter System

In this earlier article I talked about my less than satisfactory experience with Outback's newer VFXR inverters.  That cliff-hanger left the obvious question of what replaced the Outbacks.  Well, here you go....

I considered a couple of alternatives, but wanted something with proven power boost capability since that's the key feature that I need, and that kept pointing back to Victron.  They were certainly the popular choice, and I had good access to several example systems working exactly as I wanted.  So that became the default answer.

Limited space for new inverters

 

Limited space in breaker panel

One constraint I now had vs a new build was the available space, existing wiring, existing breaker configurations, available space in breaker panels, etc.  In my experience, a retrofit is driven at least as much by the as-built configuration of a boat, as it is driven by what you ideally would want.  Compromises are almost always required.  Also, Victron's product line is not exactly consistent.  They have the Multi inverters, and also the Quattro inverters.  The big difference with the Quattros is that they have two AC inputs, and the inverter will do a priority selection of which it draws power from.  This is handy is you have one shore power connection and one generator because the Quattro becomes your transfer switch and automatically switches between the two.  But I have two shore power connections and two generators, so need separate power switching regardless.  That means a Multi would be just fine, but it's not that simple.  The transfer switch in the Multi is rated for 50A, where it's 100A in the Quattro.  One of my generators is 100A, so the higher rated switch is important.  Also, the Quattros are available in higher power ratings, at least in 24V models.  All this meant that Quattros fit the bill better than Multis.

But wait, there's more.  At the time (this was all 18 months ago), Victron was rolling out the Multi II model line, with some capacity & voltage versions available, but not all.  And there were hints of a Quattro II line as well.  But the product line was not fleshed out, and some of the II models could not be paralleled where the older versions could.  Their form factor is also quite different, and they simply wouldn't fit without major reconfiguration of the laz.  Now you can see why trying to figure this out initially started to make my head explode and drove me to Outback.

Then there are all the different control buses that Victron has, and trying to figure out what uses what, how they are different, how they connect, and to what benefit.  It was another brain scrambler.  There is VE.bus, VE.CAN, VE.Direct, VE.net, VE.Smart, USB, Ethernet, NMEA 2000, each with different topology rules, different cable length limits, and different devices to interconnect them with different capabilities.  And then there are all the configuration software programs. VEBus, VEConfigure, VictronConnect, VRM, and the GX devices.  Each works with different devices, to manage different things, requiring different physical connections, and running on different platforms/devices.  Compared to other product lines where there is one communications system that connects everything, and one set of tools to configure it all, this was frustratingly complicated.

Anyway, the final decision was to use dual 8kva Quattro inverters, linked to my existing OctoGX that already tied my solar charge controllers together.  The Octo is an odd-ball device that has never had any documentation, and is no longer shown as an available product.  But it has 4 VE.Direct ports which I needed for my solar charge controllers, a VE.Bus port needed for the Quattros, a VE.Can port to connect to my Skylla chargers and my MG BMSes, a second CANbus to connect to N2K for monitoring, and an ethernet port to display and control the device itself.  Most of the Victron GX family of devices include their own display, but the Octo has none.  However you can access it via a web browser over ethernet and you get the same user interface as the built-in displays.  I planned to do the majority of my monitoring over N2K, so this all worked out fine for me.

When you go to install a Victron product, you quickly realize that it's not designed for the North American market.  4/0 DC cables are common for high current devices, and big inverters are exactly such a device.  But 4/0 cables and lugs won't fit in a Victron inverter.  Below you see two 4/0 cable lugs on the power post in a Quattro, and can see that there isn't enough space for them to lie next to each other.  The only way to get them to fit is to cut them down.

 

Not enough space for side by side 4/0 lugs

Lugs must be cut down to fit

 

Also, 4/0 cables won't fit through the opening in the chassis if there is any heat shrink on them, which of course there should be to seal the cable lugs.

4/0 cable doesn't fit through chassis opening

From this I learned that the trick is to use 3/0 cable, not 4/0.  You lose a bit of cross sectional area in the cable, but the lugs and cables fit as intended.

Victron's inverters pose another challenge when you want to build a high capacity inverter system, which is that they are 230V single phase only, and do not have support for North American split phase 120/240V power.  So you somehow need to convert the single phase inverter output into split phase.  You can do that with a full-on isolating transformer where the input side is 230V from the inverter, and the output is a 120/240V split phase.  This is how shore power is handled with an isolation transformer, and it works very well.  However 100% of the power has to run through the transformer, so it needs to be rated accordingly which makes it big, heavy, expensive, and always wasting power.

The alternative is an autotransformer which does not provide isolation, but can be used to derive a neutral for a split phase system.  And in this application, the autotransformer only needs to be sized for the imbalance between the two 120V halves of the split phase system.  So where a 100A isolating transformer would be needed on my boat, I can instead use a 25A autotransformer.   It's smaller, lighter, cheaper, and wastes less power.  The catch, which we will have to save for another day, is that autotransformer selection, grounding, and neutral to ground bonding on the boat can be very tricky, and leave you with surprising circulating current in the system when there are no loads, or a neutral for the inverter loads that is elevated several volts relative to ground.  Both of these things are cause for alarm for anyone inspecting or operating an electric system, so can create quite a problem, even if not particularly dangerous.

I decided on the autotransformer route and selected one from - wait for it - Outback Power.  They have had this product, unchanged for decades, and I have used it before successfully.  The power rating was what I wanted, and it's a nice package with a cooling fan, etc., at a reasonable price.

Outback autotransformer

Then there is another challenging issue with an autotransformer used this way.  An inverter installation will have over current protection on the inverter output sized for it's max current.  In my case that's 100A.  But my autotransformer has a max current rating of 25A, so I need a breaker for it that is 25A.  The challenge is that if the autotransformer breaker trips, the loads lose their neutral, but they still have 240V across L1 and L2 from the inverter.  With an open neutral, the line to neutral voltages will depend on the various 120V loads, and could be anything between 0V and 240V.  120V appliances do not react well to 240V, and damage is almost certain.  Worse yet, starting a fire is a distinct possibility.  So you can't, under any circumstances, allow an open neutral while still applying 240V across L1 and L2.  This means you need some sort of interlocked breaker system such that if the 25A autotransformer breaker trips, it also trips the 100A inverter output breaker.  I accomplished this using an auxiliary contact on the 25A breaker, and a shut trip on the inverter output breaker.  These are snap-on "side-car" devices for ABB breakers, designed for just this sort of thing.  Power from the Inverter output runs through the aux contacts, and to the shut trip device.  Anytime the 25A breaker is opened, it sends any 240V power that is present to the shunt and opens the inverter breakers.  So it's impossible to have the autotransormer breaker open witout the inverter breakers also opening, and you have to close the 25A breaker first, followed by the 100A breaker.  It seems complicated at first, but once you sort it out it's actually a really simple and dependable setup.

Autotransformer breaker with auxiliary contact

 

 

Inverter output breakers, each with a shut trip "side car"

It was quite the wrestling match to get the old equipment out, cables re-routed, breakers moved around, new cable access holes cut, and the new equipment mounted in place.  All I can say is that getting old sucks.  Stuff that I would just push through in my 20s and 30s, even my 40s and 50s, is noticeably more difficult in my 60s.  I'm forever thankful for a young, capable, and enthusiastic son-in-law who lives nearby.

It's good to have youthful help

 

Major components installed

Initial power-on and configuration went well.  After you get your head around all the different tools, and what to use when, it does all work.  But when I switched over to shore power, the inverters didn't start charging as expected.  Further investigation revealed that Victron inverters behave differently from all the others that I have encountered.  In particular, when AC power appears, they do not automatically start a full charge cycle.  Instead they check to see if the battery voltage is a fixed amount below the Absorb voltage, and only start charging if it's below that value.  In most charger parlance, this is called a "rebulk" setting, i.e. the voltage level where the charger will return to bulk charging.  In other products this only applies when AC power remains attached, like when connected to shore power.  If for any reason the batteries get low enough, bulk charging will resume in place a float charging.  But when AC power is gone and then reappears, bulk charging starts right away.

On a boat, this is really important when you are at anchor.  If you start the generator to make water or cook a meal, you typically want to opportunistically charge the batteries while the generator is running.  But Victron inverters won't do that unless the batteries are pretty low, and it's not an adjustable parameter.  Digging through the Victron maze of info I discovered a firmware update that reduced the voltage drop trigger point for LFP batteries, which helps, so I did the update.  But it still wasn't want I wanted.

Up until this point, I had not used so-called DVCC which stands for Distributed Voltage and Current Control.  It's used to allow the battery BMS to direct charging, rather than programming each individual charger to operate on its own.  I decided to give it a try since a friend had been using is successfully on a nearly identical power system.  With one clock of a button in the GX device, everything worked.  The batteries charged right up to full, then settled down to a lower float voltage to maintain 100% with no ongoing charge current into the batteries.  Exactly right, and I have left it on ever since.

Although the power system does what I need it to do, the Victron products are not without warts.  Here are the key things I have run into.

Charger output will likely fall short of specifications.  I haven't been able to figure out why, but with these larger Quattros it's common for people to see closer to 170A of charge current vs the specified 200A.  And that's at 25C ambient or lower where it's supposed to deliver full output.  And to add to the mystery, mine actually does come pretty close to specs, but I don't know why mine and not someone else's.  In contrast, the Skylla chargers put out 100A, as specified, all day every day.

Inverter output is not what you might expect.  An 8kva inverter is 8kva only under a very special load condition, and is really 6.5kva by all other measures.  And that's at 25C ambient.  At 40C it drops further to 5.5kva.  The result is transient overload warnings for loads that you wouldn't expect to cause a problem.

Idle power consumption can be significantly higher than the specs claim.  I haven't measured it specifically on the boat's 8kva 24V Quattros, but I have measured it on a pair of 48V 8kva Quattros and it's DOUBLE what the specs say.  The two inverters, doing nothing, consume a constant 200W.  That makes them the largest power consumer on the boat.  More than refrigeration (all fridges and freezers combined), more than Starlink, just more.  It's rather obscene.  I asked a senior Victron employee about this at METS this fall and he told me that I was measuring it wrong, and that the sampling interval of my current clamp was inadequate.  For that to be the case, the sampling from the clamp meter must be exactly in sync with the AC component of the battery current, and in phase such that every sample is picking up a peak of the AC component.  What are the chances of that?  And it means that everybody else's clamp on meter who has measured this is similarly in perfect sync and phase with the inverter.  There's NFW.  And this includes Victron's own ammeter inside the Quattro.  Man, it's lottery day if that's the case.  So I asked if I put a scope on the cable, would it show the correct current, and he said yes, it would match the spec.  OK, I'm going to do it when I'm back on the boat and we will see what we get... but I call BS on this one.

DC Ripple voltage can be an issue with Victron inverters, even though no other inverter manufacturers seem to have an issue with it.  This goes hand in hand with the current issue above.  An inverter is an electronic switch that turns on and off rapidly to create the output waveform and drive loads.  That switching results in pulse loading on the batteries at the switching frequency.  There is also lower frequency pulse loading at the AC output frequency of 50 or 60hz.  So if you look at the DC voltage at the inverter with a scope, you see a slightly wiggly line rather than a perfectly straight line.  The wiggliness (a technical term) is the "DC ripple".  Too much of it can stress capacitors and shorten their life.  For some reason, Victron monitors this, and generates warnings and alarms, and will even shut down if it's excessive.  Nobody else cares about this, so does it mean that Victron is doing us some special favor that nobody else is?  If they were, then I'd expect to see lots of failures in other inverters, but that's not the case.  Alternately, it could mean that Vicron has a vulnerability that others don't, and they are protecting themselves.  This seems much more likely to me, but we will never know.  Regardless, if your DC cables aren't fat enough, or are too long, you can end up with ripple warnings under higher loads.  And there is no sure way to know how fat or how short those cables need to be.  You can just do your best and cross your fingers.  I got lucky on this, and seem to be free of ripple warnings, but others have not been so lucky.

All this has been in operation for over a year now, and meets the major requirements, despite the little annoyances.  The one thing that really does piss me off is the idle power draw.  Twice the spec?  Are you kidding me?  If I thought there were a better alternative, I would honestly be going the Outback route and making Victron take the equipment back and refund my money.  But they seem to be the lessor of evils.  It's sad that that's considered a success.

Outback Inverters - Not Anymore

 This earlier article about inverter power boost is background for this article.  As I mentioned, my power system design relies heavily on inverter power boost to help manage loads when they temporarily spike above the available shore power or generator capacity.  This almost completely eliminates the need to do manual load management on the boat, and was a mandatory feature in any inverter I was going to select for use on 6837.

When evaluating inverters, Victron was high on the list.  They have power boost, and I knew people who were actively using it, so I was confident that it worked.  But I found it incredibly frustrating and time consuming trying to find all the info I needed on Victron's products.  It's not that the info isn't available.  Quite the contrary.  They are the most open inverter vendor that I have encountered.  But it's a maddening treasure hunt to try to find it all.  Most vendors have a product web page with links to all the pertinent technical information.  Victron has that, but it only includes links to a superficial manual, and a few other scraps of info.  Everything else is scattered across three or four different web sites (Victron.com, Disqus, Victron Community, Victron Professional) with no organization whatsoever.  And some documents are PDFs, while others are just HTML web pages which makes assembling a document library very difficult.  In fact, it's something I shouldn't have to do at all.  The manufacturer should do all that for me to aid in selling their product.

I spent weeks pouring over manuals, web pages, searching, learning something, searching more, trying to figure out how to piece together a system that would meet my needs.  At the same time, I discovered that Outback Power had a new version of their inverters that now included the power boost function.  I had well over a decade of experience with outback products, including their inverters on N6062.  They have one of the most confused user interfaces that I have ever encountered, but once set up they just work, and work well.  I had previously rejected them because they didn't have power boost, but with this new revision they now met my requirements.  By this point, I was so fed up with trying to figure out Victron that I decided to switch my focus to Outback. 

Outback Features from 2017 Datasheet

Having been schnookered before over advertised features that I later find don't really work, I decided to check out Outback a little more closely.  I found a user forum, and was able to confirm that people were using the product and that this power boost feature was working for them.  Great, decision made.

Four Outback VFXR Inverters Powering N6837

 

Dial forward to commissioning of N6837, and I had a bunch of issues getting the Outback system working properly that in the end turned out to be software bugs.  No problem, that happens, and all seemed to be working OK after updates.  Well, not entirely, it turns out.

After taking delivery, we moved to BC and spent a few days out in the Gulf Islands.  During the second day at anchor, it was time to recharge the batteries, so I started up the generator.  The inverters connected to the generator, started charging, then disconnected a few minutes later.  Huh?  This had worked fine on shore power.  After a bunch of messing around, I found the only way to keep the inverters connected to the generator was to run them in "Generator Mode" rather than "Support" mode.  Generator Mode is more accepting of different generator wave forms, but as the mode names imply, it means that the Support feature isn't active.

I also discovered another problem which is that the voltage sensing in the Outbacks is very sloppy.  For starters, voltage settings are only in increments of 0.2V, and sensing doesn't appear to be more accurate  than +/- 0.2V.  There also is no remote sensing of battery voltage, so inverter load or charge current will induce further voltage inaccuracies.  With lead batteries this doesn't really matter, but with LFP it does.  I found that when charging off of shore power at a lower charger rate, the batteries would charge to full just fine.  But if I charged off the generator at a much higher rate, the outbacks would think the batteries were full well before they really were.  And if I adjusted the charge voltage for the higher charge rate, when I charged slower it would overcharge the batteries.  There was just no setting that worked well in both cases.

But wait, there's more.  The inverters claimed to put out 82A of charge current each.  With 4 inverters, that means 328A of charge current, assuming I have the requisite AC input power, which I do.  Well, I never saw more than 250A-260A of charging current out of those inverters, so that wasn't living up to specs either.

The charging issues were frustrating, but not having power boost mode was a killer.  After much back and fourth with Outback, their insistence that I had a crappy generator, they finally fessed up that the boost function didn't work with stacked inverters.  WTF?  OK, I can actually be patient, so I offered to work with them to get it fixed, told them that my boat was just a short distance from their headquarters and that I'd be happy to have them aboard to instrument and sort this out.  Nope, they said that engineering was in the middle of a new product and wouldn't spend any time on this.  I pointed out that this feature was prominently advertised and that I built this system on the presumption that they weren't just making that up.  Nope, they couldn't help me.  OK then, I said I wanted to return all the equipment for a full refund.

Outback Datasheet Continues to Advertise "Generator Assist" in 2022 Even Though They Admit it Doesn't Work.  This Datasheet is still on their web site as of today, Jan 23, 2024.

That started a 6 month cat and mouse game to get return approval, tear out all the Outback equipment (at my expense), convince them that I had returned the equipment, and actually get my money back.  Not once in the whole process did they do what they said they would do, respond when they said they would, or in most cases ever respond at all.  I uniformly had to hound them multiple times to get any response at all.  In the end I told them that the next email was going to their parent company CEO, with a CC to their legal department and the SEC.  I pointed out that they are a public company prominently advertising that they have an important competitive feature, when that feature doesn't work, and they know it doesn't work.  I'm no attorney, but that sounds like securities fraud if I've ever seen it.  A couple of weeks later I finally got a refund check.

Bye Bye Outback

 

Regardless, to this day they continue to claim they have this feature.  Here is what's on the web site today (Jan 23, 2024) for the VFXR products, still highlighting Generator Assist as a feature even though they know it doesn't work.

Web Site Still Highlights Generator Assist

Needless to say, I'm done with Outback products, and they have earned a well deserved place on the Wall of Shame.

Inverter "Power Boost" Feature

 Many modern inverters have a "power boost" feature that is super useful.  I'm really talking about combined inverter/chargers, but I'm just going to call them inverters for simplicity.  When you are plugged into shore power, or running a generator, that power source is limited, typically to 30A or 50A.  If you overload it, a breaker trips.  To keep this from happening, it's your job to manage the power loads on the boat to keep them under the limit of the power source.  This typically means limiting how may appliances are turned on at once, not heating water while cooking dinner, etc.  Doing this isn't the end of the world, but it's kind of a pain.

For some time now, inverters have been able to help with this by varying how much they are charging the batteries.  In addition to all your boat loads, the inverter itself is an additional load when it's charging your batteries, and can consume close to, if not all of the available incoming power.  These smarter inverters have a setting where you can tell them what the incoming power limit is, and they will only use for charging whatever capacity is left over after powering the other loads.  So if your shore power is 50A, and your boat loads are consuming 30A, the charger will consume no more than 20A, ensuring that the shore power isn't overloaded, and no breakers trip.

This has been a great help to boat operators, but it has limitations.  In particular, the inverter can control how much power it consumes, but it can't control what boat loads are placed on the inverter.  So going back to our example, if the boat loads are 55A, there is nothing the inverter can do to reduce that, and you will trip a breaker.  But then along comes "power boost".

Those clever inverter engineers realized that not only could they reduce the internal charger consumption to manage the shore power load, they could actually turn the inverter back on and use it to supplement the shore power to support even larger boat loads.  So these super-smart inverters will see a boat load of 55A, and they will use the inverter to draw from the batteries to supply 5A to supplement the 50A from shore power, and now the loads work without tripping any breakers.  Then when the loads subside, the inverter goes back to charging to replenish what it took from the batteries.  Pretty cool, right?

This takes another huge bite out of power management on a boat.  You can now exceed shore power capacity by whatever your inverter capacity is.  You just need to be sure that the average consumption is less than the shore power capacity so you don't continually draw down the batteries.  This simplification to load management is so great that I depended on it in our power system design.  For example, our shore power connection is 50A, yet I know that the HVAC system can exceed this for periods of time.  But this power boost feature allows that to still work with a much more common 50A power connection vs a much less common 100A connection.  We almost never have to do load management.

Commissioning - Testing, Finding, Fixing

Spring 2021

The other primary goal of commissioning is to test everything, find issues, and fix them.  These are complex boats, each one-of-a-kind in many ways, and completely built by hand.  That leaves a lot of opportunity for things to be not quite right, so EVERYTHING needs to be checked and tested.  And I arguably went over the top on this.  I had been locked out of the yard for the last 9 months of the build because of COVID, including all the sea trials and system shakedown.  My original plan was to find as many issues then so they could be fixed quickly by the yard before the boat even shipped, but that wasn't possible, so everything had to be done once the boat arrived in Seattle.

I was determined to really check everything carefully, figuring that more time spent during commissioning would mean fewer issues once we started cruising, and that seems to have paid off.  It took a long time to get everything sorted out - 9 months to be exact - but it was worth every day since we subsequently had a nearly trouble free 6 months of cruising.  Nothing stopped us, or even slowed us down which is how we like it.

My "checklist" of things to confirm/test was just short of 700 items, and I went through each and every one of them.  Every piece of equipment was inspected to confirm it was as intended, was installed correctly, and worked as expected.  Much of it went quickly, but along the way you inevitably find problem that need to be fixed.  Here is a sampling of some of the things that we needed to work through:

• Standard equipment on the boat is an electric selector valve to switch between the two water tanks.  It was stuck and just threw an error when we attempted to operate it.  The valve had to be replaced.
• I had ordered higher capacity vent fans for the heads, but that got lost along the way and the boat was built with the standard fans.  So they needed to all be replaced.
• There was no fuel return for the diesel boiler.  It can be installed either with or without a return, but servicing is much easier when there is a fuel return enabling it to self-bleed, so I had specified that in the build.  So a return line had to be installed.
• I have two identical alternators on the main engine, and the panel meters were showing unequal output from them, yet a clamp meter on the positive cable showed they were equal.  It was a while before I dug into that problem, and it turned out to be a negative cable connection that was supposed to be isolated from the alternator frame, but was making contact and allowing a bunch of the return current to flow through the engine block and the boat's ground system.  That was a good one to find and fix, and now the meters always read the same.
• One of my contract requirements was that all machinery be mounted on rubber isolation mounts.  It makes a huge difference in how much machinery noise is transmitted through the boat.  There were a few places where the yard missed this, so they had to be added.  On my previous boat (N6062) you could hear the freshwater pump running throughout the boat.  On this boat, with the isolation mounts, the only place I can hear it is in the master bathroom which is directly over the pump, and only if I'm really listening for it.
• We have a hot water circulating pump that circulates the hot water on demand so you quickly get hot water at a faucet without having to run the water forever, wasting a bunch.  There were a handful of issues with how it was plumbed, the location of check valves, etc. so it needed to be reworked a bunch.  We also relocated the pump to a more accessible location.  Also, the pump was super noisy.  At first I thought it was just because there were no isolation mounts, but even after installing them it was still really noisy.  It turns out it was a Grundfos look-alike pump, not the real thing.  My specs called for a Grundfos, so it was replaced and is now silent.
• We had a bunch of very odd error messages from the Outback inverters about mismatched version numbers, lost phases, etc.  All inverter versions were the same, everything was wired correctly, and this turned into a huge time sink trying to fix it.  After a lot of experimenting I finally discovered that the Cat5 cables linking everything together were not terminated correctly, and on close inspection you could see clear issues, and some even failed with a cable tester.  Whoever installed the cable plugs was clearly doing it for the first time.  I rebuilt all of them, and that got everything working - or at least working a lot better.  It was months later that I cam across a firmware update, and one of the fixed issues had to do with reports of firmware mismatch. Sigh.  There is more to the Outback story that I'll post about later.  Spoiler alert - they are no longer with us....
• The exhaust for the diesel heat had not been built to specs.  i think the yard was just accustom to building them a certain way, and didn't look at what the boiler requires.  So the exhaust had to be rebuilt.
• In a conversation with Glendinning about my power cord reel, I discovered that it was installed somewhat backwards.  Glendinning wants the power reel directly above the bucket, but mine was installed at the cord inlet.  Apparently if installed that way the cord is much more subject to jamming and tangling, so we had to rearrange the cord reel installations (two of them).
• Lewmar overhead hatches.  What a disaster.  Everyone of them leaked.  Then I came across two pallets of them in the shop that had similarly leaked on other new boats.  Lewmar claimed to have found and fixed the problem, and sent us new hatches, all of which leaked.  So we removed them all and replaced them with Manship hatches.  No more leaks.
• In testing all the horn buttons I found one where the spade terminal had pulled off.  Simple fix, I thought.  Nope.  It turns out the buttons have screw terminals, and the yard got creative and tried using spade lugs pushed over the screw terminals, but they weren't secure.  So we replaced all the horn buttons.  i really like these orange buttons that make the horn stand out from other buttons on the console.
• On sea trial there was a distinct vibration in the main drive line, and on further inspection we found the shaft was not running true.  After a bunch of additional head scratching and measuring, we concluded that the coupler was probably not machined correctly.  So the boat was hauled, shaft pulled, coupler separated, and it was clear that there was a poor fit between the shaft and coupler.  The contact area was minimal, and the couple appeared to not be seated true to the shaft, which would explain the wobble in the shaft.  Off it all went to the machine shop for refitting, then everything went back together along with a laser shaft alignment to be sure everything is true.  Now it runs great.
• A very concerning problem was a low oil pressure alarm during our first sea trial.  There was just under 40 psi which seemed OK to me, so we assumed it was a false alarm of some sort.  But it happened again when the Scania distributor was on for their sea trials and application review.  On further investigation I found that the pressure was indeed low, with Scania wanting it in the range of 60-70 psi.  Long story short, it ended up being a faulty oil bypass valve in the oil filter housing.  Pressure went right to where they belonged after replacing it.  The filter was replaced and old one dissected to be sure there was no sign of contamination, and there was none.  Problem solved.
• Toilets.  You would think manufacturer's would have this one figured out by now, but it seems not.  The first problem were the new designer toilet seats with no visible hinges.  Great, but they don't open far enough to rest against the wall that the toilet backs up against.  If they do get pushed back against the wall, it flexes and stresses the hinges and structure and guess what?  They break.  One broke the first time someone did a pretend sit-down test of the toilet.  So those all needed to be swapped out for the non-designer seats that work and don't break.  Classic designer crap....looks great, doesn't work.
• Toilets.  Then there are the internal vents in the toilets that let air in behind the flush water.  When you flush, it sends a slug of water down the drain pipe.  That slug pushes air ahead of it which vents out the holding tank vent.  The slug of water also pulls in air behind it, and that air needs to come from somewhere.  There is a little "air admittance valve", aka a vent valve built into the toilet to accomplish this.  Without it, air will be pulled through the water trap in the toilet and go glug, glug, glug, or worse yet it will suck the water trap dry allowing fumes back up through the toilet.  So this vent valve is pretty important.  We had the same Tecma toilets on our last boat and they worked great, but this time the toilets all went glug, glug, glug after flushing.  Thee was a lot of back and forth with Tecma over this, and I was ultimately able to prove that the vent valve wasn't opening easily enough, so air was being pulled through the water trap.  Long story short, I ended up sourcing vent valves with a much lower opening pressure, and that 80% fixed the problem.  But it's still not low enough - just as low as I could find.  I don't know what changed between my last toilets and these, but the vent valve on the new ones just doesn't work.  In all other ways I really like the Tecma toilets, but this was pretty pathetic.
• In the bottom of the day tank there is a water alarm sensor, and it was leaking.  This one took a few attempts before we realized what was going on.  It turns out that the probe on the end of the sensor was bottoming out in the fitting used to insert it in the tank, and that was preventing the o-ring from sealing.  A quick trip to the local hydraulic and fitting shop produced a different style fitting with sufficient clearance.  Problem solved.

This is just a sampling, but gives a sense of what's involved in shaking out a complicated boat.  It's massively different from a mass-produced automobile, and still significantly more complicated than a custom home.  This ends up being a major source of frustration with new owners who don't know what to expect.  I was thankfully coached on this by others when we built N6062, and that build taught me even more.  After selling N6062, I read back through my maintenance and repair log, and every single thing that emerged as a problem during our ownership of that boat showed itself in one way or another during commissioning.  Some of the clues were subtle, and brushed off, but they were there.  That's why I spent so much more effort on N6837, and tracked down every little strange thing until it was explained or fixed.