At the end of April I published “One Year & 7300nm later; Most & Least Favorite Möbius Features April 17-30 2023” which was Part I of the first year review reporting on what has now been well proven to work the best for us and were our favorite features.  Since that post we have put another thousand nautical smiles under our keel as we meandered our way up to our final destination for a bit at Tidewater Yacht Marina in Portsmouth VA just across the river from Norfolk Virginia.  That passage totaled just over 8200 nautical smiles and we are going to push the Pause button and stay here for the next few months.  If you missed it, I provided a more detailed update on this last leg of our latest journey in the previous post you can read HERE.

This will be Part II with our review of those things which have not worked out as well as hoped, our least favorite features and things to add/change to make Möbius even better than she already is.  I’m delighted to report that our least favorite list is much shorter than our most favorites so this Part II will be much shorter than Part I.

As with Part I there is no implied ranking in the order of these items and I’ll group them as Design based or Equipment based.


I’ll start with Design based changes and note that given the enormity of this project and that we pretty much started from scratch, we have been pleasantly surprised at how few design decisions we and our brilliant Naval Architect Dennis Harjamaa made that we would have done differently.  Even these are all best categorized as things that would be improvements to the current design and build.  We have also passed on all these observations and recommendations to the new owners of the two XPM’s that are currently under construction in Antalya right now and to the builder for future new builds.

Extended SuperSalon/Pilot House

Depending on weather, this space is where we spend a majority of our time at anchor, especially for meals and evenings and it continues to be a joy to live in.  However, we have come to realize is that it would have been very easy to extend the length of this superstructure by one frame which would have made this room about one meter or three feet longer.

011 SuperSalon LayoutIf you click to enlarge the plan view from our design files and the rendering below, you can see the layout of the SuperSalon as it was deigned and built. 

MOBIUS_SALOON_RENDER (4)As you can see, we had intended for two lounge chairs to go in the space to the side of the dinette table.
Fridge - Freezers dry fitted to cabinetryHowever, along the way we ended up deciding to install the two drawer style fridge/freezers inside the cabinetry on the Port side which is at the bottom behind the backs of the chairs in this rendering above.
Eames Chair metric dimensionsWhen we moved aboard, we put two admittedly large comfy lounge chairs in as per the layout you see here, but after using for a month or so we found that this proved to be impractical needing to access the Fridge/Freezer drawers and so we have removed one lounge chair.
This is has been our setup ever since and works out fine but means that when we are having our nightly “dinner and a movie” time watching the large 50″ TV in the forward Port corner, one of us needs to be seated in either the Helm chair or on the settee with the table put down into “coffee table” height. Having that extra meter of length would have allowed each of us to have our own lounge chair which would make our evening entertainment time even more enjoyable and comfortable. I know, I know, poor pitiful us right?!

On the plus side we discussed this with Naval Yachts and with Chris and Sebrina when they were designing the layout for their XPM78-02 Vanguard and decided to add that extra meter and it has made their SuperSalon even better than ours.


We made natural or passive ventilation, especially when at anchor, a high priority as we were designing Möbius and most of the time it has worked well but when the weather is warmer but not quite hot enough to justify running Air Conditioning and when the winds are low ventilation in the primary living spaces, the SuperSalon and the SkyBrdge, are places where the ventilation can be improved the most. 

Ventilation: SuperSalon

MOBIUS_SALOON_RENDER (1)One of the many great things about being at anchor is that you know that all the wind is going to be coming over the bow and flowing aft so we took advantage of this to bring those breezes into the boat. There are three ways we bring natural ventilation into the SuperSalon area, two which bring the breezes into diffusers in the ceiling and a third with the air that flows through the large hatches in the Master Cabin and up into the SuperSalon.  Ventilation via the Master Cabin flow through works well but the two independent ventilation systems for the ceiling diffusers do not provide as much ventilation as we had hoped. 
Underside PH Vent under overhangOne of the ways the air enters the boat is through a series of slots cut into the roof overhang in front of the negatively raked front window which is highlighted in Red in this rendering.  This location creates a slight high pressure zone that we wanted to take advantage of to help bring some fresh air inside.
PXL_20230611_163839514This is what the real thing looks like.  The space behind this grille connects through pipes into a large plenum or box in the ceiling overtop of the Main Helm Station.
PXL_20230611_170000087In the ceiling overtop of the Helm station these five Black diffusers connect into that plenum and are adjustable to change the volume of air and the direction of the air flowing in.  All good but there was supposed to be ducting used to bring the air from the grill box through to each diffuser and because this was not done all the air fills up the plenum and loses all its pressure and so there is not good flow of the air into the boat.
PXL_20230611_163800540The second fresh air intake is located up here but is hidden from view when these three solar panels are in the closed or down position for when we are at sea.
PXL_20230611_164123055Those three panels are mounted on a single frame that is hinged on its back side such that it can be lifted up and held in place horizontally like this.  Very simple and quick operation to remove two locking pins on the front and lift the panel up and lock the support braces in place.  Having the solar panels horizontal can also help increase the power when the sun is overhead.
PXL_20230611_164145235This position creates this massive wedge shaped wind tunnel which directs air coming over the boat to flow through the “mist eliminator” grill my finger is pointing to which removes most of the humidity and airborne salt as the air flows through.
PXL_20230611_170036378Similar to the forward Black ceiling vents this air flows through into a large plenum above these White diffusers you see here which directs the air down into the Salon.

Unfortunately, this system was built the same with with no ducting and so the flow rate is similarly compromised and produces much less air flow than expected.
PXL_20230611_191502273Our interim solution for now has been to use this vertical rotating fan which works surprisingly well and is very quiet but longer term we will retrofit some ducting to the ceiling diffusers which should be much more efficient at bringing the breezes into the SuperSalon.

Ventilation; SkyBridge

IMG_1577Up in the SkyBridge there is excellent air flow available because each of the acrylic window panels are easily removable.

PXL_20230605_232209013To provide great ventilation up in the SkyBridge we came up with a very simple and easy way to remove/replace each of the 8 side and 2 rear acrylic sheet windows so that we can open up or close in the SkyBridge as the weather changes and this has proven to work really well.  To remove any of these windows you simply lift it up the bottom of each panel and as you can see here the bottom edge now just clears the cut down inner sidewall section of aluminium U channel that holds each panel in place.

PXL_20230605_232141278The top edge of the panel slides up into the extra space at the top of these upper U channels so as you pull the bottom of the panel inside and down so it slides out of the upper frame channel you see here.

A good example of the KISS Keep It Simple & Safe approach we used throughout the boat and takes mere seconds to remove or replace a window panel.
PXL_20230605_231943739Even though it is June 11th as I write this, the weather here in Portsmouth has been surprisingly cold, dropping down to 14C/57F last night for example.  Brrrrrrrrrr!!  So right now we have just removed one acrylic panel from each side and this allows us to slide the other three panels back and forth to block any wind or rain.  In this photo I’m pointing at the edge of the acrylic panel that is behind my hand to the rear and the area to the front on the Right is wide open.
PXL_20230605_232001715This different angle might show this opening a bit better with my finger again pointing at the edge of the acrylic panel with the open space forward.  If we removed all 13 acrylic panels all four upper sides of the SkyBridge are open and air flows through. 
IMG_3122Very often too much breeze coming through especially through these three front facing windows so we tend to keep these in place all the time. 

So once again, what’s the problem Wayne??!!  Best description is the lack of the “Goldilocks” just right amount of ventilation up in the SkyBridge when we are at anchor.  Too much if we remove these front three windows and not enough if they are left in place.
IMG_1573The problem is that with the wind coming over the bow, if these front windows are in place they deflect almost all the air down the sides of the SuperSalon and even if these side window panels are removed the airflow is such that it all flows straight back along the sides and too little air flows into the interior of the SkyBridge especially up at the front in the lounge area.

PXL_20230611_163749715Fortunately I think that the solution is relatively easy to create.  The idea would be to convert these glass panels from being permanently fixed in place to panels mounted into hinged frames so each glass panel can be open and closed.  Perhaps this would only need to be done to the three front facing panels and leave the side glass panels fixed as well as being able to remove the upper side acrylic windows making it an even easier modification.

SkyBridge Windows View Obstruction

IMG_1572The SkyBridge on Möbius has proven to be our most favorite area for both helming the boat underway as well as lounging up there when at anchor so this is where we spend most of our time unless the weather turns cold and wet, which in the past two years has not happened much at all.  The 360 degree views from up here are difficult to capture in photos but you’ll get some idea here with this view forward from the Lounge area.
IMG_1577and this view from the Upper Helm chair.  So what’s not to like Wayne??
IMG_1569It may seem very minor to most, but when you are sitting down in the Lounge settee your eye level is the same height as the horizontal aluminium break between the lower glass windows and the upper acrylic sliding windows.  So when I’m looking out that seemingly thin bit of aluminium gets in the way of your view and has become a pet peeve for me.  You can sit lower or higher to see over/under this but the views would be so much better if your sight line was about 30cm/12″ higher such that you were looking through just the acrylic windows.
IMG_1570The best solution I think would be to build a raised platform about 30cm high for the lounge settee and table to sit on.  This could be a welded AL platform but what I think I will do when I have the time is build a wood frame for the platform and cover with marine plywood as a first prototype and see how it works. 
The floor of this raised platform could be covered with the left over vinyl flooring that has worked out so well in the other living spaces  and there would be the bonus of having a very large storage space under the platform floor for larger and bulkier items such as deck/beach chairs and such.

That covers all the most significant design based changes of we have recommended for the next XPM78 boats which are built.  Other minor ones are things such as decreasing the height of the stair risers, basically adding one additional stair step to each to make it easier to go up and down these stairs.  The current ones are a bit too much of a step up and down for most people and not quite that Goldilocks just right height.  Easily fixed during the build process but not something we will change on Möbius and instead see this as a feature rather than a bug by keeping us in good physical shape each time we use the stairs.


The other area where improvements and changes would be recommended is with some of the equipment that is used in some of the systems onboard.

FireFly House Batteries

IMG_20190920_122217The most disappointing equipment issue has been my decision to go with FireFly Carbon Foam batteries for the large 1800Ah @ 24V house battery bank.  If you’re interested in the fully detailed description of the situation you can go back and read the post I wrote back in August “No Fire at FireFly Batteries?”   It really is a very sad and disappointing situation as these Carbon Foam type batteries are a fabulous solution for many boats and owners and I’m hopeful that another company will pick up the patents and start manufacturing more soon.  The problem was not with the chemistry but with the lack of quality control at the factory which resulted in far too many of these batteries losing their capacity very early in their life. 

IMG_20200706_125429In our case, the capacity loss began after about six months of use and has continued to slowly decline more and more ever since.  On the good news front, we have been able to continue to use the boat full time every day with almost no problems using the existing capacity these batteries do have so it has not been disruptive to our day to day living and cruising.  In fact we have only been plugged into shore power twice in the past year on some brief stays in marinas.  This is all thanks to having so much capacity to begin with in the 24 individual 4V @ 450Ah batteries that make up our House Bank, as well as having so much solar from our 14 320Watt solar panels that brings the house bank up to 100% SoC each day.  Plus anytime we are underway we have the two Electrodyne alternators able to crank out up to 9kW of power to charge the batteries if we need to go days without much sun.
This is another reason that we will be staying put here in Portsmouth so I can decide what to chose for the new battery replacements.  Right now this is most likely to be some good quality AGM batteries or perhaps Gel based “traction batteries” but I’m still researching what the Goldilocks replacement choice will be.  Lithium is what most people would think of but in our case they don’t make as much sense as we actually value the weight of our House Batteries providing part of our overall ballast and we have plenty or room as you can see above.  There also appears to be growing evidence that one of the odd characteristics of both Carbon Foam and Lithium is that they prefer to NOT be kept fully charged to 100% all the time and I believe that this was part of what caused our batteries to fail prematurely.  More research to follow and I’ll provide updates here whenever I make the decision on the new House Batteries.

Reducing Engine Room Extraction Fan Noise

Vent Box ductingOne of the other equipment based changes we would make is to find ways to reduce the noise from the extraction fans which ventilate the Engine Room.  These run whenever Mr. Gee is running to keep him supplied with fresh air and to exchange the air in the Engine Room frequently to help extract the heat and keep ER temperatures as low as possible.  Not able to photograph the whole setup as it is welded into the hull and ER but you can see how the Red boxes are welded to the Aft Deck plate and then the Purple aluminium ducting runs in/out of the ER below.

Aft Deck Vent Boxes The existing fans do the job very well and as extraction fans go they are not too loud.  However, because the entry and exit grilles are located in these two vent boxes on the Aft Deck the noise they do make travels up into the SkyBridge and can be a bit distracting.  One of those things you don’t notice so much until you do.  I’m not sure how much this can be reduced but I will be researching fans that have been specifically designed to be quieter and look into whether moving the fans from inside the Vent Boxes to down inside the ER itself might reduce the decibels a bit.

Circuit Breakers as On/Off Switches

PXL_20230611_211123293There are two circuit breaker panels on Möbius, this one on the Starboard/Right side of the Main Helm for all the 24 Volt circuits that are best accessed from there such as deck lights, navigation equipment, etc.  These are all double throw circuit breakers so they control both the positive and negative sides of each circuit and this has al.l worked out very well. 
PXL_20230611_211221017Then there is this larger panel with all the circuit breakers for the remaining equipment in all four voltages; 120V + 240V AC and 12V + 24V DC. 

The issue is a minor one of convenience.  Because there is a circuit breaker for each individual piece of equipment, no On/Off switches were installed where the equipment is installed.  In most cases this is just fine but for things like pumps for transferring fuel and water, desk wash pumps and things like that, it would be handy to have an On/Off switch right there when you want to turn on a Deck Wash pump for example.  This would simply save me a trip up to the circuit breaker panel so this is just a matter of convenience
Easy enough to solve the problem and I have purchased some nice On/Off switches to mount nearby these types of devices and just need to find the time to install them all.

Bosch washing machine

PXL_20230611_213126010I’m not sure if this is a common problem with this model perhaps but our Bosch washing machine has failed three times since it was installed and has been very annoying to have to remove and repair.  The first two times it was under warrantee but it failed again while we were making our way through the Bahamas and so is on my list of repairs while here in Norfolk. 

What makes this particularly annoying is that none of the Bosch service technicians seems to be able to identify just what is causing the problem and they simply replace every circuit board inside and reinstall. 
PXL_20230611_213134139Even worse, once the washing machine does quit it shows an error code on the LCD screen but as soon as you shut it off, it will not turn on again, not even the screen, until after the problem has been fixed.  So unless you take a picture of the screen when it happens there is no way to turn the machine back on and figure out the problem!  Fortunately I take photos of these error codes but even with that none of the service techs or my searches online can tell me what the problem is so I’m at a loss to know what to fix. 
Will just need to break down and have them come out to the boat to replace the circuit boards for a third time but sure is annoying!

I should add that all our other appliances on the boat such as induction cooktop, oven, etc. are all Bosch and are working extremely well so no knocks to the company, just the lemon of a washing machine we seem to have lucked out with!


And that’s about it for the list of things which we’d recommend change on next builds and things we will be doing to improve what has already been a fantastic boat.  Surprisingly few breakages in the time we’ve been underway and living onboard which says a lot for any boat and makes us VERY happy.  About the best testament that can be given I think to ALL involved with converting our dreams into the reality that Möbius now is and we are eXtremely grateful to each of you and our special thanks to Dennis Harjamaa for his brilliant design work and everyone at Naval Yachts for their work building Möbius.


Hope this review of both what has worked the best and the least well will be of value to other boat owners out there or future ones.  I know that I value first hand experience over just about all else and so glad to pass on what I’ve learned in our experience with Möbius so far.  Please do let me know if there are other specific questions you have related to all this or of any kind and I’ll do my best to respond as quickly as possible.