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

Hi everyone,

I'm a huge fan of boats – especially long-range expedition yachts. My personal inspiration is something like a Bering, but without the charter aesthetics or unnecessary fluff. I’m not building this for guests or for show – just for us (2 people and a dog) to live aboard and explore for months at a time.

This has been a dream of mine for years – to design or convert a vessel into something truly self-sufficient, honest, and purposeful. I'm now looking into support vessels or workboats under 300 GT that could be converted or even newly designed for this kind of use.

What I’m looking for:

• GT under 300
• Length somewhere between 28–40 meters
• Deck space for 2 tenders + 2 Sea-Doos – doesn't have to be huge; something smart and efficient
• Absolutely no crew quarters – we’ll run everything ourselves
• Diesel range of at least 3,000 NM (ideally more)
• Built for autonomy and real use, not marina life
• Large storage space for food, water, fuel, parts – everything for long-term independence
• Strong simple interiors – no marble, no bow lounges
• Hydraulic systems over electric (reliability and cooling)
• Ice-rated or at least North Atlantic capable hull is a plus
• Quiet, efficient, redundancy-focused setup

I’m reaching out because I’d love to meet people who enjoy designing things that don’t exist yet – even just for fun. If someone here likes to play in CAD or sketch concepts, I’d be thrilled to talk. Later I can share all the details I’ve been collecting over the years.

If this sounds like your kind of project, I’d love to hear your thoughts. Whether you’re a designer, refit veteran, or just someone who appreciates this kind of boat – welcome aboard!

Thanks for reading,
Josef from Switzerland

 

Boat looks top heavy. Would not be comfortable in a strong crosswind. Avoid heavy seas. Might be a desirable marina queen, appears that it might have many creature comforts.

 

That would be illegal. Check the manning regulations for vessels over 100 tons
Federal Register :: Request Access https://www.ecfr.gov/current/title-46/chapter-I/subchapter-B/part-15

 

Thanks, @gonzo – appreciate the input.

Just to clarify: I'm not planning to flag the vessel under the U.S., and the boat will be strictly for private, non-commercial use. No chartering, no cargo, no passengers beyond myself and my partner.
From what I understand, the U.S. manning regulations (46 CFR Part 15) apply to commercial vessels under U.S. flag – which is not my case.
I'm currently considering flag states like the Cayman Islands or Cook Islands, where private vessels over 100 GT can legally operate without dedicated crew accommodations, provided they’re run by the owner and not used for hire.
So yes, you're absolutely right for U.S.-flagged commercial vessels, but in the private, non-U.S. context, the crew quarters are not mandatory.
Thanks again – I welcome any more input or advice!

 

Thanks for your thoughts @messabout , I appreciate the input.

Just to clarify – the image I posted is of M/Y Miss Sarah J, an Inace Explorer 95 built in 2003. It’s not a stylistic marina showpiece but a true steel-hulled expedition yacht with serious long-range capability.
While it might appear top-heavy in photos, it’s actually a full-displacement vessel with deep draft, steel hull, and a very low center of gravity. This model was designed for real ocean crossings, not just coastal cruising. She has crossed the Atlantic, operated in the Caribbean and Pacific, and is known for her sea-keeping and stability – even in tough conditions.
That said, I'm not buying her as-is. I'm looking at vessels like this to potentially refit for fully private use (no crew quarters, no charter), with a strong emphasis on autonomy, efficiency, and simplicity. But I value your comments – they help push the thinking further.

Thanks again!

 

Surely the Cayman Islands (and also the Cook Islands) subscribe to the Rule that vessels over 24 metres re their Loadline length are required to have crew with relevant qualifications, even if they are being used privately, rather than commercially?
I think it would be rather difficult to get a 40 metre (or even a 28 metre) yacht with modest overhangs to have a loadline length of less than 24 metres.

 

There are some fundamental questions here, like why 28-40m for 2 persons, why have the auxiliaries on deck instead of housing them in a garage, what's "long term" and "months at a time", but I'm sure you already have answers to all of that.

Anyway, boats like you describe do exist, more or less. Take for example this one, Hang Tuah - Nigel Irens Design https://nigelirens.com/boats/power-boats/hang-tuah/ I'm sure it can be made to fit the bill. Adding ice reinforcements and specifying all hydraulic equipment shouldn't be a problem for someone like Nigel Irens. She's large enough to carry all the supplies you'll ever want, especially after you converted the crew quarters to storage.

 

Motorboats are much easier to control than sailboats , nevertheless I can imagine that you can need more hands on deck at this boat size.Or very extensive automatic systems.

 

@Rumars

Thanks – that’s a very thoughtful reply, and I appreciate the Hang Tuah reference – beautiful concept.
As for why not go with enclosed garages: it’s mostly about GT management. I’m aiming for a vessel under 300 GT, and enclosing tenders adds a lot of “volume” under the official tonnage calculation.
An open working deck with hydraulic cranes lets me stay well under that limit, keeps everything accessible and ventilated, and supports my long-range logistics – which is the priority.
This isn’t a charter vessel or a marina queen. It’s meant to be a practical explorer for two people and a dog, where function matters more than form.
But yes – I agree that concepts like Hang Tuah show how far creative thinking can go. It’s great inspiration.

 

@bajansailor
Thanks – great point about Load Line rules and the 24-meter threshold.
You're absolutely right that vessels over 24 m Load Line Length often trigger more formal requirements under the IMO LLC – especially for manning and certification.
However, flag states like the Cayman Islands do allow private yachts >24 m / <300 GT to operate without dedicated crew under certain conditions – especially if the vessel is:
– Not used for commercial purposes
– Operated by the owner
– Below 12 passengers

Cayman has exemptions under their Private Yacht Code that specifically address this.
So yes, technically these thresholds exist, but there are flag states where private operation without crew quarters or hired crew is still possible, even above 24 m LLL – which is what I’m aiming for.
Appreciate the insight – helpful to keep in mind as I refine the scope!

 

@montero
you're absolutely right that size adds complexity.
That’s why the vessel will be fully set up for 2-person operation, using:
– Joystick docking
– GPS-based station keeping
– FLIR/IP cameras
– A complete Maretron/NMEA2K monitoring system

But I also plan to be pragmatic:
In tricky ports, congested canals (like Panama), or tight fuel docks, I fully intend to hire local deckhands or pilots temporarily. Not often – but when needed.
This isn't a marina-hopping vessel. The goal is to stay out for months, only coming into port for fuel, provisioning, or emergencies.
So yes – the automation and redundancy are there for day-to-day, but I won’t hesitate to bring help when it makes sense.

 

Well, Hang Tuah is 149 GT, so there's no conflict with your requirements in that department.

Having presented the 41m boat, let's go in the other direction, because I do happen to think that there's no need to go above 24m for what you desire. A good example for this is the FPB 70, SetSail FPB » Blog Archive » FPB 70 – A New Baby Sister! https://setsail.com/fpb-70-a-new-baby-sister/ a boat specifically designed for double handed owner operation. I am sure you can find space aboard for the dog and two jetskies. Unless you have some unusually high space needs (say for example you want a full workshop with lathe, mill, welding table, etc.) that's all the boat you should go for.

You can read about the development of the entire FPB series here: Evolution of the FPB Super Cruiser https://dashew1.rssing.com/chan-12089295/article347.html
They are no longer in production, but at least one of the series is usually for sale, you don't have to spend years on designing and building.

 

@Rumars

Thanks for the FPB suggestion – I like the series and the philosophy behind it. But our case is a bit different, and here’s why a 30+ meter vessel is essential for us:

• We’re installing full-size cold storage – not just a few domestic fridges or freezers. We're talking about commercial-grade walk-in fridge and freezer rooms, installed midship below the main deck to keep the center of gravity low. That alone takes significant volume and weight capacity.
• Our dog needs dedicated outdoor space – we plan to install a artificial turf patch or similar deck zone for daily movement and comfort.
• We live aboard full-time, and we’re planning for 6+ months of remote cruising. That means full wardrobes, proper storage, backup systems, tools – not just toothbrushes and T-shirts.
• We carry two Sea-Doo Explorers, each over 3.5 m and 400+ kg. This requires open deck space, hydraulic lifts, and safe launch systems – which just don’t fit on smaller platforms.
• We’re building a real floating home, not a minimalist cruiser. We want a galley, dining, salon, helm, ensuite, guest/crew cabin, and possibly a tech room or workbench. Not to mention tankage, autonomy, and redundancy.
  In short: we’re not trying to squeeze into a boat. We’re designing a small, independent ship – fit for two humans, one dog, and many months at sea.

 

Circa Marine in New Zealand are now building their own 24 metre version of Dashew's FPBs - as Rumars notes above, I see no reason why you need to go bigger than this for what you want.
Luxury Yacht Builders NZ | Circa Marine https://circamarine.co.nz/FPB-yachts

 

@bajansailor
Thanks for the input – I appreciate the reference to Circa and the FPB legacy.
That said, I’d like to kindly note:
I’m not looking for advice on how small I can go, but exploring what’s realistically needed to comfortably support a long-term lifestyle with redundancy, storage, and autonomy at sea.
What I need or don’t need isn’t really the point here – the thread is about feasibility of a specific setup (layout, GT limits, technical considerations).
I’m not the type who looks for reasons why something won’t work – I’m here to solve how it can.
So please don’t take it personally, but repeating that “there’s no reason to go bigger” doesn’t reflect the context or long-term mission planning behind this.