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

Just to clarify — not stepping on anyone’s toes here, just keeping the discussion on track:

I’m not here to debate what's “theoretically possible” — I've already done that homework.
I've calculated the volumes, payload, autonomy requirements, storage needs, and what kind of layout and space is necessary to support long-term, liveaboard life for two adults and a dog.
I’m fully aware that this pushes the envelope for a privately operated yacht.
But this isn't a weekend cruiser or a charter vessel — it's a floating home with high autonomy and full onboard logistics.
So yes — I do understand that someone somewhere once crossed the Pacific in a 6m sailboat or soloed the Northwest Passage in a kayak. But that’s not what I’m building.

Let’s please move past suggestions like “you don’t need this” or “why not just go smaller”.
I’ve already figured out what I need — now I’m looking for realistic suggestions on how to build or refit a platform that matches those requirements.

Thanks to everyone who's sharing constructive input — that's what helps move things forward.

 

When I think about long stays at sea, I'd like to understand all the vessel's systems. I'm not a great fan of electronics. Can you handle servicing complex electronics in the middle of the ocean? It's like modern diesel engines. I'm trying to understand what the designers of the popular Ford Transit engine were thinking, but I'm slowly losing my mind.
A stupid diesel heater has too much electronics IMO , and I'd prefer something simpler and easier to understand. Something that can be diagnosed without a laptop.
Complex systems are nice, but won't you need an on-board engineer?

 

@montero
Great question — and honestly, it's one of the core reasons I chose this kind of vessel.
I’ve been a building maintenance technician (Haustechniker) for over 25 years, working with HVAC, plumbing, electrics, automation systems, fault diagnostics, and everything in between.
So it’s probably easier to ask what I can’t fix — because in 90% of cases, I can sort things out myself.

Also, vessels of this type — long-range expedition yachts — are often built with simplicity, redundancy, and fail-safe systems in mind.
They may have modern navigation or monitoring tech, sure — but under the hood, they’re often mechanically straightforward, especially compared to mass-produced motor yachts full of hidden automation.

I’m not interested in overcomplicated things — I’m aiming for robust, serviceable systems with backup for anything critical. If something software-based goes down, I can reflash firmware, swap modules, or bypass as needed.
No laptop? Then we go to Plan B — and the boat keeps running.

Engineer onboard? No — not needed. Not for us. Only if we hit Panama Canal or tight mooring, I’d call in local deckhands. Day-to-day, we’re fully self-reliant.

 

This is quite important information. Without this knowledge otherwise it would be difficult to handle .

Don't you think that a tight mooring or the Panama Channel aren't the worst-case scenarios at sea? What's your maritime experience?

 

@montero
I appreciate the concern — but I didn’t come here to be audited on my captain’s license, medical history, health status, stool consistency or risk profile.

If I followed that logic, I might as well just stay home on the couch — because something might happen if I step outside.
But life’s not about avoiding all possible risk. It’s about managing risk with planning, skills, and the right vessel.

But none of that changes the core of this discussion: I’m designing a boat for specific use, and I’m looking for people who want to solve — not just warn.

So again: if anyone has ideas about hulls, layouts, or platforms that fit this brief, I’m all ears.
If not — no hard feelings, but please let’s not derail the thread with hypotheticals about doom and gloom.

 

But you realize these are important things, including stool consistency and sometimes medical knowledge. A two-person crew, a huge ship, weeks on a wind crazy ocean, and that dog. It's sounds like some movie scenario . Sometimes you have to go to sleep. And the physical limitations of the body play a huge role.

Regarding the overall layout of a boat, something like the Bering is too uneconomical for me. It's a waste of energy. Steel construction also makes no sense to me.
Aluminium or composite build and definitely not an ordinary monohull. And why do you need these jet skis? As if there weren't better toys...
When it comes to an ordinary steel ship, the cheapest option will be to adapt some cutter.

 

@montero
I respect that everyone is entitled to their own opinion — but no one asked what you personally find meaningful or not. That’s not the question on the table. If jet skis, provisioning capacity, or a particular layout don’t make sense to you, that’s perfectly fine — but that’s not the point of this thread.

Rather than evaluating my choices or explaining how you would do it, it would be far more helpful to stick to the actual brief. If you don’t have anything constructive to contribute to that, I’d kindly ask to refrain from derailing the discussion.

We’re here to find solutions — not to endure unsolicited lectures from people who clearly aren’t willing to understand the basic concept that has already been explained several times.

 

Ok, so you basically got a plan for a general ararrangement. I presume you also got ideas about some of the equipment you wish to use, at least the domestic life part.
If so what exactly are you looking for in the discussion? What "realistic suggestions" can we make when we don't know anything about your desires and plans? I'll give you just one example, heating. Do you prefer hydronic or air? Do you wish the heating to function on battery power alone or be completely independent from electricity?
If you tell us what you dreamed up, we will probably have opinions about your ideas. Be prepared to accept that there will be some topic where some of those opinions will inevitably be negative. I for example find the ideea of a centrally located walk in freezer at least questionable. Food doesn't care about vessel motion, you can just as well fit it into the bow and keep the space closer to the CG for humans.

You got to understand that you have zero chances of success in designing a new boat of this size and complexity by yourself, and 0.1% of successfully designing a refit of an existing platform. Normally at this stage you take your detailed wish list to the NA of your choice and start paying for his hours.

 

@Rumars

Thanks for your message.

Yes, I’ve done the necessary calculations and functional breakdown. This includes storage volume (including walk-in fridge/freezer/dry store), autonomy range, redundancy levels, and operational logic for two people and a dog. I’ve also studied several reference platforms (e.g. Miss Sarah J, Inace Aft House 126), and discussed the potential need for a minor extension or redesign with a naval architect who’s now preparing a proposal.

What I’m currently seeking is input regarding:

• existing platforms that could be adapted to the mission (below 300 GT),
• technical suggestions related to layout, build techniques, and modular design that supports long-term liveaboard autonomy.
  

I’m not expecting to design the boat myself – nor am I building it solo. I’m assembling a clear SOR and GA concept to hand over to professionals (naval architect, shipyard, etc.), which is exactly what I’m doing.

As for feedback – I’m happy to hear constructive ideas and honest critique, even disagreement. But that requires reading the actual brief instead of jumping to conclusions.
The walk-in freezer? It's exactly where it belongs for load balancing and daily access. Not every design is just about minimizing motion – sometimes it's about weight distribution, plumbing efficiency, and vertical access from the main deck. That’s not theoretical – it’s already implemented on comparable explorer yachts.

So again: if someone knows a real-world example of a yacht that fits the spec, or has technical input based on actual experience – I welcome it. But if the only input is that I should lower my expectations or abandon the plan, then we’re probably just on different frequencies.

All the best,
Josef

 

Honestly, sometimes I wonder if I'm in a boating forum or a forum dedicated to finding reasons why something can't be done.

I ask a straightforward question about layout or vessel design — and in return, I get lectures about storms at sea, mooring challenges, and unsolicited opinions on what I "really need."
People here seem convinced they know exactly what's right for me, without knowing me, my goals, or the broader concept.

Let me be very clear:
I'm not conducting a survey on what others believe I should want. I'm planning a long-term liveaboard vessel, not a weekend toy.

If I followed the logic some people suggest, I’d never leave my bunker.
Because:
– A branch might fall on me in the forest.
– I might get hit by a car.
– My house could collapse.
– The sea has waves!
– Electronics might fail!
– Hurricanes exist!
– And... there’s a canal in Panama!

So, what? Should I stay in a fireproof, waterproof, earthquake-resistant padded room, wearing a helmet and strapped to a chair?

I’m not looking for reasons to give up — I’m looking for concrete, technical solutions.
If I say I need two Sea-Doos, walk-in freezer space, a wardrobe for year-round clothing, or space to walk my dog — that's not an invitation for debate. It's part of the spec.

If you don't want to answer the actual question, that's totally fine. But please don’t derail the thread with off-topic personal opinions or speculative doubts.
Thanks to those who actually engage constructively. The rest — kindly scroll on.

 

Are you certain that you will be able to register this vessel with a flag state that will allow you to operate her without crew, even though she will be considerably larger than 24 metres Loadline length?
If so, I am just wondering why more people are not doing the same as you. There are many large motor yachts of all types that appear to be designed to come under this 24 metre rule. And they must have a good reason for doing this.
The San Lorenzo 96' motor yacht is a good example of this - here is an excellent thread on the YBW Forum describing the construction of one of these vessels.
New build Sanlorenzo SL96A 2024 https://forums.ybw.com/threads/new-build-sanlorenzo-sl96a-2024.593911/

And here is a link to her on her Builder's website
SL96 Asymmetric - Yacht - SL Range - Sanlorenzo Spa https://www.sanlorenzoyacht.com/uk/yacht/sl96-asymmetric.asp

 

@bajansailor
Operating a Yacht >24m Without Crew – Legal, Possible, and Widely Misunderstood
I’ve noticed this debate resurfaces every time someone dares to think outside the 24m “comfort zone”. And yet, the same myths get parroted back:
“You must have crew. The law says so. If not, why isn’t everyone doing it?”

Let’s break that down. Properly. With facts and citations — not hearsay and "friend-of-a-friend" logic.

1. Legal Foundations: Load Line Length ≠ Overall Length
When regulations reference “24 metres”, they mean Load Line Length (LLL) — not the yacht's overall length. This is defined under:

International Convention on Load Lines (ICLL), Article 2:
“Length” means 96% of the total length on a waterline at 85% of the least moulded depth…

This is why yachts like the Sanlorenzo SL96A (LOA 29.06 m) or Princess Y95 (LOA 29.1 m) are intentionally designed to keep the LLL under 24m — to avoid regulatory burden. Builders do this not because you must stay under, but because it’s the path of least resistance.

2. The Law: Private Yachts >24m Can Operate Without Crew
If the vessel is not commercially operated (i.e., no chartering, no paid guests), then many flag states — including Cayman Islands and Marshall Islands — explicitly permit owner-operation without crew, regardless of LLL.

Cayman Islands Shipping Registry (CISR):
“Private yachts, even over 24 metres Load Line Length, may be operated without commercial certification or crew requirements, provided they are not engaged in trade.”

Even the MCA Large Yacht Code (LY3) confirms this:
MCA LY3 – Chapter 1, Scope:
“This Code applies to commercial yachts of 24m and over in Load Line Length. Private yachts are outside the scope of this code.”

So unless you’re carrying paying passengers or flying a flag that forces you into commercial compliance, there is no legal requirement to hire crew — even above 24m.

3. STCW, SOLAS, ISM – Only Apply to Commercial Vessels
The STCW Convention on crew qualifications:

STCW Regulation I/2:
“This Convention shall apply to ships engaged in commercial operations.”

Again, not relevant for Private Pleasure Yachts.

4. Why Don’t More People Do It?
Good question. Here's the honest answer:

Because people are told they can’t — by others who never bothered to check.

You ask why more people aren’t doing it? Look in the mirror.
You are the reason. Or more accurately — the mentality you're expressing.

What we have here is the classic “my brother’s friend’s wife’s cousin knows a guy who once met a surveyor who said you need crew if it’s over 24 metres.”
And this gets repeated, over and over, with zero citations. But with absolute, unwavering confidence.
So when someone like me walks in with actual legal documents and registry policies — I’m told:
“Well, I’ve never heard of that. If it were true, everyone would do it.”
No.
They don’t do it because people like you convince them it’s impossible — without any factual basis.

Let’s Be Honest
Most yacht owners:

• Don’t study the legal frameworks
• Don’t want the hassle
• Prefer to follow what the industry tells them is “normal”
  

So builders keep producing “just under 24m” boats with stubby sterns and extended swim platforms — not because of law, but because of market psychology.

Final Thought
If you're convinced that a >24m yacht must have crew, then I challenge you:
Which exact regulation or law mandates that private pleasure yachts over 24m LLL must be crewed?
Can’t answer that? Then stop presenting myths as facts.

Let’s move the conversation from “I heard” to “I checked”.
Because spreading regulatory fiction does more harm than good.


Additional Perspective: Why Builders (and Owners) Avoid >24m LLL – It's Not Just Psychology
While I mentioned that many yacht owners follow what the industry tells them is "normal", there's a far more concrete reason why both buyers and builders try to stay under 24m Load Line Length:

A yacht over 24m LLL severely limits your registration and resale options.

Yachts over 24m LLL:

• Cannot be registered as Private Pleasure Yachts in most European countries (e.g., France, Germany, Spain, Netherlands, Italy)
• Are subject to commercial maritime conventions (MCA, SOLAS, MLC) regardless of charter status in these jurisdictions
• Require compliance with class societies (e.g., RINA, DNV, Bureau Veritas)
• Face greater scrutiny during port-state inspections
• Are harder to insure privately in some countries
• Drastically reduce your buyer pool upon resale

Even if you're a capable owner-operator with the right flag (e.g., Cayman or Marshall Islands), you’ll likely face resistance if you ever want to sell to a buyer based in mainland Europe.

Yachts under 24m LLL:

• Can be registered as private vessels nearly anywhere (EU, UK, US, CH, etc.)
• Are exempt from most commercial standards when not chartered
• Don’t require professional crew certification
• Are easier to insure, transfer, flag, and sell
• Attract a wider market of potential buyers — especially first-time owners and EU-based clients
  

In Summary
Staying under 24m LLL isn’t about safety.
It’s about avoiding red tape, broadening market reach, and protecting resale value.

That’s why builders engineer designs to hit 23.9m LLL —
not because going longer is illegal,
but because selling a 26m LLL yacht in Europe is a nightmare.


I genuinely hope that I’ve now provided you — and others with similar assumptions — with enough factual, verifiable information to put this matter to rest.
Let this be the final word on the subject:
Yes, you can legally operate a yacht over 24m Load Line Length without crew — and no, it’s not a loophole, it’s just law.

 

All this dialogue about the legality of running a boat without a crew…the practical problem is you don’t even have a 2nd dockhand and the helmsman cannot leave the station unless anchored, so the real problem is this vessel cannot be brought into port safely. The first mate will be overtasked and bear unfair burdens. What you are doing is a form of fallacy. It is where you present an argument (the legality of operating without a crew) to support your wishes (to operate a large vessel crewless), but the entire time avoiding the real questions surrounding the basics of bringing such a vessel into port or other demands for a 3rd crew member. Based on the thread contents, you will not discuss the logistical nightmare of landing the vessel (among others), but will rationalize away from it.

I can find places to flag my vessel for lawful operation, therefore it must be okay to do it is unsound thinking. The right way to go about it is to first recognize the nightmare, then to discuss ways to mitigate it, with a 3rd crewman as one solution.

Finding a flag to support your desire does not make it wise.

I have no experience on such a large vessel, but perhaps you can build control systems like thrusters that can assist. For sure it is out of my wheelhouse, but I’m amazed at the pattern of thinking I see. It is not a good tack.

 

@fallguy
Thank you for your concern – but you’re missing the point, and worse: you’re ignoring what’s already been said.
You're absolutely right that operating a large vessel without proper planning would be reckless — which is exactly why this project is anything but.
What you describe might apply to traditional boats – but not to a vessel refitted from the ground up with:

• Hydraulic bow and stern thrusters
• Joystick maneuvering + remote mooring systems
• Dynamic Positioning Assist (DPA) using GPS
• Full camera coverage
• Redundant helm controls

This is not a fantasy – this is engineering.
And before you continue preaching “logic,” let me remind you of a few things you conveniently missed (or chose to ignore):
I already stated that for tricky dockings, a deckhand or even a local captain can be hired temporarily. This solves 99% of what you're calling a “logistical nightmare.”
Logically, why would I pay crew to be onboard 24/7 when the yacht will spend most of its time underway or anchored in remote bays?
You’re arguing against something that wasn’t even asked.
I didn’t ask for reasons why something is impossible. I asked how to implement it properly.

Yes, storms happen. And for that, we plan, we equip, and we train. That’s seamanship.
What you see as a fallacy, I see as a challenge worth solving. This is not about "finding a flag to cheat the system." It’s about building a safe, autonomous, liveaboard explorer for two people and a dog – with no compromises.
So unless you have a constructive suggestion, maybe steer your energy elsewhere. Some of us are here to build smart, not just complain loud.

 

If one person falls overboard, how will you respond? Serious question.