Dream project: Converting a support vessel <300 GT into a long-range liveaboard expedition yacht

[Josef Brychta]

Hey @Varn ,

One thing that still surprises me: I haven’t seen any vessel — new or old — that’s truly designed around this logic. Everything seems either built for charter, or optimized for two-person operation but still looks like a marina queen with multiple lounges, oversized salons, and blink-blink interiors.

I get that resale is often a concern when going off the beaten path, but honestly… I’m not convinced that will be a problem. More and more people are looking for genuine autonomy, rugged build quality, and smart systems rather than glitzy showpieces. And if the time ever comes to sell, I have a feeling there will be a small but serious market for a boat that was actually designed to go places — and not just look good doing nothing.

Appreciate your continued input — it’s rare to find someone thinking along these lines.

Josef

 

[Josef Brychta]

Hey Varn,

Thanks again — really appreciate the thoughtful back-and-forth.
One thing I’ve built directly into my SOR is a deliberate shift away from "charter logic". For example:

• No king-size master suite — just a practical queen bed. My partner and I sleep spoon-style anyway, and I’d much rather use the saved space for a proper wardrobe. Clothing for four seasons needs more than two drawers.
• No formal dining area for 10+ guests — just space for 2–4 people max. Realistically, it’ll just be the two of us and the dog.
• Instead of luxury lounges, I’ve prioritized storage, mechanical access, and system redundancy.

One very specific requirement is an artificial grass patch for the dog — with a drainage grid underneath that can flush either to blackwater or directly overboard. It needs to be on the aft deck or flybridge, and I want the ability to switch drainage based on weather (e.g., rain shouldn’t fill the blackwater tank unnecessarily). Miss Sarah J ticks that box well, since the flybridge is enormous.

Also, I’m keeping the guest/crew cabin small — with optional bunks. Just enough to meet port requirements (like the Panama Canal) or host short-term tech crew if needed. Definitely not building for entertaining.
This isn’t about having a yacht that impresses at the dock — it’s about creating a tool for long-term life afloat.

Josef

 

[Josef Brychta]

Hey Varn,

One more thing I’d like to share — because small systems details matter just as much when you're only two aboard.
As I’ve mentioned earlier, the boat will be equipped with joystick steering and a full fly-by-wire control system. Remote plug-in points for the control unit are planned in three zones:

• Aft deck (port and starboard),
• Midship by the wheelhouse (port and starboard),
• Forward deck.

It might seem like a small thing, but for a two-person operation, having flexible control from multiple spots is a huge contributor to safety and ease of use — whether docking, anchoring, or managing gear.

Another system that gets overlooked on many vessels is access security. I’m planning a hydraulically fold-up swim platform that can seal off the entire stern when raised. It serves as both a safety measure (for preventing unauthorized boarding, wild animals, etc.) and a functional barrier in rough anchorages.

All hydraulics — including the swim platform, passerelle, davit crane, and underdeck hatch — will have manual backup operation via a hand pump, in case of primary system failure. These redundancies aren’t flashy, but they matter when you’re the only ones onboard, hundreds of miles from help.

I'm also evaluating the option of installing a stern (aft) anchor. While it's not yet confirmed, it's under consideration as part of improving positioning control in tight anchorages, shallow coves, and during long-term mooring in tidal or variable seabed conditions. The challenge is to ensure integration without compromising the aft swim platform, which is planned to be fully foldable and lockable for safety and security.
Additionally, the yacht will feature retractable side boarding steps on both port and starboard sides, fully integrated into the hull. These will allow safe and comfortable boarding when docked alongside or when using a tender — a critical feature for a vessel operated by just two people without permanent crew.

I guess that’s the theme of the whole design — minimize assumptions, maximize systems independence.

Josef

 

[Varn]

Hey Josef,

I’ve been following your posts with interest—not just for the technical depth, but because your overall approach makes a lot of sense to me.

I’m not directly involved in yacht design, but I’ve spent a fair bit of time around ship systems and operations—enough to appreciate how rare it is to see someone actually designing for function over form.

The way you’re prioritizing autonomy, cold storage, and working access over glamor really stands out. I think a lot of people would go for this kind of setup if they had the money — I know I definitely would.

A few things came to mind as I was reading through your recent posts—not critiques, just ideas from a practical angle that might be worth considering:

Provisioning access: The underdeck hatch setup is brilliant. Just thinking aloud—would there be any value in having a simple manual-access alternative (like a folding step-through or narrow service ladder), in case the hatch or crane system goes offline mid-cruise? Could help in non-port scenarios or maintenance downtime.

Cooling and waste heat: With so much cold storage and compressor activity, have you considered routing some of that waste heat into the hot-water system or even into cold-weather heating zones? I’ve seen this done on commercial vessels, and it’s a quiet way to stretch energy efficiency.

System zoning and failure isolation: You’ve mentioned modularity and backups—which is great. Just wondering if some of the physical infrastructure (like cabling or hydraulics) will also be split across separate routes/zones. If not fully redundant, at least physically compartmentalized. Might pay off in the long run.

Data logging + trends: Since you’re integrating Maretron and pulling a lot of real-time data, I wonder if you’ve thought about using something like a simple onboard NAS or Pi setup to run long-term trend tracking. Even basic energy drift or compressor cycles over time could flag early inefficiencies.

Dog zone drainage: The drainage-switchable grass patch is such a thoughtful idea. Just a small thing, but in enclosed conditions, will you be incorporating passive odor management (carbon filter, ozone, etc.) to prevent buildup? Not urgent—just curious how deep you’re going on that side.

Honestly, it feels like you’ve already mapped out 95% of this with real-world logic. Just wanted to share a few loose thoughts in case they help trigger anything useful down the line.

Looking forward to seeing how it all takes shape.

— Varn

 

[TANSL]

I like all these elaborated ideas, and Josef, I think you have lucid answers for everything. But, just thinking out loud, doesn't anyone care whether the structure will be able to accommodate and support all of that, whether the ship will comply with SOLAS, IMO, MARPOL, etc., whether the ship will have the necessary stability and buoyancy? It's possible that it doesn't need to comply with any regulations, but insurance companies may ask for certain assurances. In short, does anyone care about the aspects of naval architecture and its relationship to safety?

 

[Josef Brychta]

Hi Varn,

Thanks for the thoughtful questions — exactly the kind of feedback that helps refine the concept even further.

Redundant access in case of crane/hatch failure
Yes, that’s already accounted for. As shown in the layout examples (see Stairs-1/2/3 from the Inace Explorer 120), there will be manual stair access between decks, marked in yellow. These stairs provide an alternative route in case of hydraulic or electronic malfunction — particularly useful in remote anchorages or emergency situations.

Heat recovery from cold storage systems
Absolutely. The cooling compartments (located port and starboard of the aft lazarette) are fully separated and will be equipped with dedicated glycol-based systems. Heat exchangers will route excess thermal energy into the domestic hot water loop and optionally into cold-weather heating zones. All major systems are zoned for fire safety and thermal isolation.

Hydraulic system redundancy
The entire hydraulic infrastructure — including lines for the crane, swim platform, and hatch — will be fully redundant. Each key function can be switched to an alternate loop in case of failure, and we’re also installing manual backup hydraulic pumps for critical operations.

Data logging + diagnostics
All system data — including compressor draw, cycle timing, and insulation drift — will be logged to a QNAP NAS unit with Starlink+local NMEA backbone. We’re also installing a dedicated Black Box for long-term system replay. Fibre-optic cabling will connect bridge, NAS, and cameras — fully redundant.

Dog deck drainage + odor control
The artificial grass patch is located on the flybridge, fully open-air. Drainage is simple: a nearby wash-down hose, natural sun exposure, and slope design should prevent stagnation. No additional odor mitigation is expected, but we may add passive carbon filters if needed later.

Best,
Josef

Barefoot | Boat Design Net - Stairs

 

[Josef Brychta]

Hi @TANSL ,

Thanks for your input — you're absolutely right that structural feasibility, stability, and compliance with class and international regulations (SOLAS, MARPOL, etc.) are all crucial in any serious yacht or expedition vessel project.

That said, I believe any design process — especially at this early conceptual stage — requires clear priorities: function first, then structure, then optimization. What we’re doing now is defining mission parameters, operational logic, and spatial needs. Without that, what exactly would we be optimizing for?

I’m well aware that compromises will follow once naval architecture and class constraints are factored in. But shaming or dismissing conceptual planning on the grounds that it hasn’t yet been through structural analysis feels… premature. It’s not how I work — and frankly, not the kind of mindset I would entrust with leading a project of this complexity.

Best,
Josef

 

[TANSL]

Hio @Josef Brychta ,
At no point have I intended to disparage anyone's work, much less belittle anyone. What I simply wanted to emphasize, and perhaps I've expressed myself poorly, is that in the design process, once some things have been defined, it is necessary, first, to have a GA to verify that there is enough space for everything that is to be incorporated into the boat and, second, to have a rough idea of what the shapes of that hull should be in order to accommodate all the equipment and achieve sufficient stability, buoyancy, and maneuverability.
With the very detailed SOR that you have developed, in my opinion, and I don't mean to disparage anyone, a very preliminary body lines plan should be made, a very preliminary estimate of weights to verify, very preliminarily, that the boat floats adequately and to check something else, for example, the desired power vs. speed. Many things would have to be done at a preliminary level, such as defining the tank capacities and checking that there is sufficient space on board. I would work like this, but that's not the only way to approach a project like this. I know. But I think more should be done than what you're telling us. Although it's likely, or almost certain, that you're already doing it even if you don't tell us.
I don't like to talk about the design spiral, but you have to take two steps back to move forward three.
Please forgive me if any of my opinions have upset you. That's never been my intention, on the contrary; I like to be positive and help those who, like you, deserve it.
Cheers

 

[Josef Brychta]

Hi @TANSL ,

Thank you for the clarification — and no worries, I appreciate the tone of your message.

The main reason I joined this forum and started this thread is simple: I’m still deciding between a full newbuild and a deep refit. The hull shapes and volume of the Inace 95 and 120 platforms are some of the few that might meet my — admittedly demanding — requirements: autonomy, storage logic, sub-300 GT compliance, and true owner-operator capability. So I was also hoping someone here might know of an even better-suited platform — if it exists.

As for my previous reaction — I admit it may have sounded sharp, but to be fair, even just in this thread, I’ve heard more about why things can’t be done than how they could. Why a vessel this size can’t be registered as a PPY. Why it can’t be run by two people. Why it’s unrealistic to do X or Y.

It’s not my style. I’ve always looked for solutions — not obstacles. As my uncle used to say: “When you don’t want to do something, it’s even worse than not being able to.”

And just for the record: behind the scenes, there’s already a large body of work being done — SOR, weights, volume mapping, system sketches, redundancy planning, and more. I'm not sharing all of it here simply because I assume most readers would find it overwhelming or unnecessary at this stage.

Appreciate your input.

Best regards,
Josef

 

[bajansailor]

This vessel Dawn was visiting Barbados yesterday - I am posting this simply to show how a relatively simple supply vessel can be converted into a much more complex vessel.
Ship DAWN (Work Vessel) Registered in Cayman Is - Vessel details, Current position and Voyage information - IMO 9756298, MMSI 319238200, Call sign ZGQI3 https://www.marinetraffic.com/en/ais/details/ships/shipid:5393906/mmsi:319238200/imo:9756298/vessel: DAWN

Here is a photo in her previous life :

And how she looks now.

 

[mc_rash]

@Josef Brychta your profile picture, your writing style and some of your ideas and opinions suggest that this thread is created with or at least based on AI, am I right?

What does AI tell you will the project of your favour cost? How are you goint to pay the costs as a Haustechniker even if you live and work in Switzerland?

Kind regards

 

[Josef Brychta]

Hi @mc_rash,

Thanks for your interest — and for your concern over how a simple Haustechniker in Switzerland might be able to afford a complex project.

You’re not wrong that I use AI tools — just like I use CAD, spreadsheets, or navigation software. They’re not there to replace thinking — they’re there to accelerate it. Maybe that’s what you’re picking up on.

As for funding: I’m not sure why someone’s job title should define what kind of goals they’re allowed to pursue. But don’t worry — no public money is being spent, and I’m not here to sell anything. Just building something I care about, with care.

Lastly, if you ever want to discuss actual systems, layout logic, or design tradeoffs — I’d be more than happy. But if you just want to police avatars and job descriptions, you’re probably wasting your own time.

All the best,
Josef

 

[CocoonCruisers]

Hi Josef and all, thanks for the interresting thread Ruminating a much lighter/cheaper/smaller/'younger' approach to not all that different lifestyle wants, i'm as sceptical as some others here about all that heft and expense thrown at the SOR (sometimes beyond the diminishing returns, one can encounter negative ones), but i certainly dig the focus !

Now in your own, may i say "comfy rightsized well-integrated & efficient, barely manageable but doable-for-a-couple" paradigm, and after all the refinement and integration work you already did to make it handlable and efficient, what i don't understand is why you'd go for a 50's nostalgia platform. Is style such a determining factor ?

Your storage and living volume needs (20 tons payload + long-range fuel tankage and 120m2 of living space maybe ?) seem nowhere near what shaped the freighter/trawler-based hulls you are looking into (more like 50t payload at the sizes discussed, probably 100t for the commercial originals). And probably you won't want to freeze in over the winter in the Arctic, so perhaps all you need is a moderate ice belt that could be retrofitted to all kinds of vessels.

In that line, by *not* going for a more modern platform like one of these north sea working cats or a little island ferry cat, you might be giving up on:
- The simplest solution against rolling that will end up driving you crazy, even in moderate swells at anchor (though there are ways to mitigate, it's always going to be some hassle, and usually some noise & energy expense)
- Finding a used refittable one recent enough to be aluminum or (comercial-grade) GRP, not steel (Keeping a steel one of the sizes you mention rust-free might be possible with just two people, but it's certainly going to be at odds with servicing all the systems and the actual captain duties. Or you'd have it stuck in a yard for months every 3 years or so to have it done preventively at great expense)
- Efficient operation at 50%+ higher speeds: the possibility to choose your passage weather to a much greater extent. While still beeing able to go just as slow and far as the displacement freighter while using/carrying half the fuel.
- Fitting all your requirements easily below the 24m limit: much easier handling with reduced crew, accessing marinas instead of just commercial harbours, beeing able to insure in more 'private' ways...
- Living totally at deck level with real windows instead of sleeping in a cave. Spending most of your days on one level (perhaps even two with an enclosed fly), and with wide views, only going down to the stores in the hulls from time to time.
- More solar surface to run your hotel loads without generator noise most of the time.
- More flexible because less longitudinal deck spaces.
- Lower draft (modern workboats are so much lighter that many cats could undercut your displacement freighter yacht). There are so many more nice places accessible to 1.5m than to 2.30.
- If it's well done, and with engines downsized to displacement/semi-displacement speeds, they might be smaller and farther away (in terms of walls / compartments in between at least) for a substantial noise advantage.

Now the refit might require some creative thinking, like a ramp system to load tenders & toys on the back of the ama's or in some kind of garage. Or just an A-Frame crane and a bit of rear deck lost to it (if you have acres of it, so what ?). But i'd think the mods wouldn't be more difficult than your below-deck loading approach for example.

Best luck with that huge and amazing project in any case !!

 

[Josef Brychta]

Hi CocoonCruisers,
thanks a lot for your thoughtful and well-argued comment – that’s exactly the kind of discussion I value. You raise excellent points and clearly know your stuff.

That said, I think it’s important to acknowledge one fundamental truth: every person has their own needs and priorities, and that’s why we have such a wide variety of cars, boats, and tools on the market. What one person might see as excessive, another considers crucial. And that’s perfectly fine.

Personally, I’m not a fan of imposing my views on others, and I also don’t enjoy when someone tells me “you should be fine with just X or Y.” I’m happy to exchange ideas – but decisions should always follow clearly defined goals, not other people’s shortcuts.

I spent two full years seriously considering: do I want compromises – or not?
And the answer was: not anymore.
I'm too old to invest 5+ million only to later say: “Damn… I should’ve just gone all the way from the start.”

As a Haustechniker, I’ve seen this mistake over and over again: save money now, pay twice later. What was supposed to cost 100k ends up costing 300k after the “cheap” fix fails. So I’ve learned the hard way: on some things, you don’t compromise.

Regarding the steel hull and maintenance:
Just because we’ll operate the boat as a couple doesn’t mean we’ll do everything alone. On the contrary – in the tropics or many ports, it’s easy to find local guys who are more than happy to clean the hull from barnacles or repaint the antifouling for a fair price. That way, I’m not just maintaining the boat – I’m also giving someone work. That’s a win-win. And i also planned yard time. The 2–3 year haul-out cycles are already built into the budget. No surprises there.

And “sleeping in a cave”? Honestly, that doesn’t bother me. I sleep there, I don’t live there. I never understood why some boats have cabins bigger than the salon and galley combined. Sleeping space is for sleeping – that’s it.

Thanks again for your insight – and don’t worry, I’m still looking at options. If there’s a platform that fits my SOR even better than the current ones, I’ll consider it. But I’m building around clearly defined needs – not trends, nostalgia, or someone else’s comfort zone.

Wishing you all the best in your own adventure – maybe we’ll cross wakes someday.
Josef

 

[CocoonCruisers]

So I’ve learned the hard way: on some things, you don’t compromise.

Well, from the SOR elements you gave so far i don't quite get where you would be making compromises with what i described - i'd think that most people nowadays would be viewing a neoclassic vessel as a far bigger compromise. But obviously it's also a matter of tastes and opportunity