Adventure 40 Interior Design

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Even if you are not interested in buying an Adventure 40, you will want to read this post. I learned a huge amount working with Erik, and you will too by reading about the process of designing an interior arrangement for an offshore boat.

But before we get going, I need to write about a few Adventure 40 fundamentals to make sure that everyone reads this post in context.

Right Ain’t Obvious

First off, there is a huge disparity between an interior that actually works in an offshore voyaging boat, both in port and at sea, and the general perception of an ideal interior for cruising, particularly among those who have not spent a lot of time living on boats and going to sea in them—much of the target market for the Adventure 40.

The Product Of Experience

This interior design is the culmination of several hundred thousand miles of experience, over 50 years of living on boats, and many hundreds of nights at sea in all weathers—and that’s just Erik and me.

Added to that, we have had the input of many deeply experienced cruisers over the last three years. I can’t name them all, but you know who you are, thank you.

The point I’m trying to make here is that we know what we are talking about.

Sorry, I know that sounds pretty arrogant, but it needs to be said. Does that mean that we are always right and that your opinion doesn’t count? Of course not. We have incorporated many good ideas from our readers, including those with less experience. Bring ’em on. But please keep in mind that if we don’t adopt your pet idea, we are not just being dogmatic, we have a good reason.

And  furthermore, you will probably get a better boat (whether it’s an Adventure 40 or not) and be a happier voyager by looking at this design with an open mind, rather than rejecting it because it does not have a feature(s) you think you need, particularly if the foundation for that perceived need was picked up on a forum.

This Is A Nine Ton Boat

Next point. Please be realistic. The Adventure 40 displaces 18,000 pounds (8.2 metric tons), light ship. That’s the same size as a Westsail 32 and a lot smaller than a Valiant 40.

Forget the fact that she is 42-feet long. Interior volume is a function of displacement (not length) and there is simply no design trickery that can change that basic fact. We simply can’t squeeze more stuff in. So if you want to see something added, think about what you are willing to take out to make room for it.

An Offshore Liveaboard Two Person Boat

This project is about building a truly great boat for a comparatively narrow mission: to take two people offshore voyaging, including living aboard for long periods, with occasional guests/crew.

  • She is not a boat for a large family with a cabin for every member.
  • She is not a boat for those that want to have guests stay for long periods.

Trying to make her into either would ruin the boat in short order. She would end up with too many berths, very little storage, and terrible access to all her gear—just like all the other marina-queens out there.

One day we may do a 25,000 pound boat that will work for more people over longer periods (probably about 50-feet long) but this is not that boat.

To summarize, sure we could probably sell more boats by making the boat fit a wider mission criteria. But every time we added a feature just to sell another boat(s) we would weaken the design. We are not going to do that. This is not about selling the maximum number of boats. It’s about building a truly great boat for the mission defined above.

Preliminary Design

We are still in the first stage of the design spiral and there are many details left to be worked out. So please don’t demand to know, for example, what stove (cooker) we will be installing or exactly how many gas cylinders of what size you will be able to stow. We won’t know things like that until we:

  • first, 3D model the boat;
  • second, build a full-size mock up of the interior.

And even then, I’m betting we will be changing things on the prototype when we get her sailing. Rest assured that you, our readers, will be part of the process every step of the way through posts and discussion here at AAC.

The Evolution of The Interior

I’m going to start off with Erik’s and my first crack at the interior arrangement, and then move on to what we have ended up with while explaining the process. Yes, I know this makes the post really, really long—you think it’s long to read, try writing it—but doing it this way will help everyone understand how we got to the present arrangement, and that’s important to understanding why she will be a great boat.

Click on plan to enlarge

Click on plan to enlarge

At first glance it appears that we got everything we wanted in our initial specification, and even managed to add a chart table, which had been sacrificed for the shower. But wait, this arrangement has a lot of problems. Many of them typical of most cruising boats.

Let’s start from the bow:

  • The forepeak is minuscule.
  • The V-berth is a long way forward resulting in a very narrow foot. Footsie with your lover is great, but foot-wars, not so much.
  • The head is small, a long way forward, too far from the companionway, and the head itself is oriented athwart ships—all terrible sins for an offshore boat. You will have to go to windward for a few days to know how horrible these weaknesses are. The potty stories I could tell you…no, let’s not go there.
  • We have a pilot berth, but it’s really cramped, and worse still the outside shape of the berth must conform to the hull shape to accommodate the sleeper’s shoulders. But this means that on starboard tack he or she will be sleeping head below feet, and on port tack the opposite. Sounds trivial, I know, but if you try it for a few days you won’t think so.
  • The salon seating area is too narrow, resulting in a narrow table that will be awkward at mealtimes.
  • We have a chart table, but it’s very small and a person using it must sit on the head of the settee bunk without any back support.

So what do all these problems have in common? Two things:

  • We fell into the classic trap of trying to get too much into the volume at our disposal.
  • We ran out of boat length.

Both are problems that many modern designs suffer from.

The fix is not to ignore the problem and build a boat that’s awkward, as so many are, but to grasp the nettle and get rid of some things—great design is a lot more about having the guts to leave something out than trying to cram too much in.

So we:

  • Ditched the pilot berth. It was too small and ill-shaped to be comfortable, and anyway pilot berths are not all they are cracked up to be at sea. For a start, getting in and out of them is at best difficult and at worst down right dangerous when they are on the high side because of the risk of falling right across the cabin.
  • Cut out the chart table. As I have said for years, navigation is best done on deck and the Adventure 40 will have a great place to do that under the hard dodger. Those who want a ship’s office—justifiable I might add, I’m writing this post in one—take a deep breath and don’t panic, great things are coming to you.
  • Made the boat nearly two feet longer on deck, although no bigger.

An Interior That Works

Click on plan to enlarge

Click on plan to enlarge

Those three changes let Erik come up with a truly brilliant design. Here is one of the best, maybe the best, offshore cruising boat interior layout I have ever seen in a boat this size.

But before we get into the details, let’s all step back a moment and think about the fundamental conflict in offshore voyaging boat design:

  • The interior must work well at sea.
  • But even the most dedicated voyaging couple probably spends less than 10% of their cruise actually offshore. The rest is spent living on the boat at anchor or alongside.

Most modern boats do reasonably well at the latter, but fail miserably at the former. And if you are not comfortable at sea, you probably won’t get to enjoy the boat at anchor for long because at least one of the crew will quit after the first tough passage.

Erik has dealt with this difficult dichotomy brilliantly by splitting the boat into three zones:

  • Forward of the mast we have a large master cabin. A place to share intimacy with your partner…and to escape when you want a break from that same partner. A place where you can write in peace and quiet, or call mom on the phone. This is pretty much exclusively an in-port area. Think of it tricked out with some nice art, a patterned duvet cover, and some throw cushions.
  • Aft of the mast and forward of the companionway is the dual use area: a great working area at sea, and a great living area in port.
  • Aft of the companionway is all of the machinery, a place to work on said, parts storage, and everything required to be stowed below but accessible from on deck.

Nothing is mixed up, as it is on most boats of this size:

  • No deck gear stowed in the accommodation; for example, slimy fenders stowed on a berth.
  • No wet watch stander dripping water all over you every time he or she wants to take a pee or make a cup of tea.
  • The partner rebuilding a pump, with unmentionable stuff on his or her hands, is safely separated from the living area and the nice reward dinner being prepared in the galley. Heck, the partner reading in the forward cabin, after finishing food prep, probably won’t even hear the muffled curses as a screw strips on said pump.

OK, let’s dive into the details, starting from the bow:

The Details


The forepeak is truly cavernous for a boat this size, at 6-feet (1.8 meters) long and 5-feet (1.5 meters) wide at the aft end (at the deck). It will be separated from the forward cabin by a watertight crash bulkhead that is actually far enough aft to do some good, and can be accessed through a hatch from on deck.

Since the anchor chain is stowed just forward of the mast, there will be even more usable room.

This will be a great place to store light air sails like an asymmetric spinnaker and or a code zero and other light stuff like fenders. And the really cool thing is that you will be able to set and stow these sails directly from the hatch with no need to drag them through the accommodation.

Forward Cabin

The forward cabin is a true “owner’s cabin” with a queen size berth a full 5 feet (1.5 meters) wide at the head and over 7 feet (2.1 meters) long, with “bedside tables” and a storage shelf each side.

We are also looking at designing a movable headboard that will pop up to give you a place to rest your pillow, but slide down to facilitate getting in and out of the bunk.

There will be plenty of room for storage under the berth and each side in lockers, one with shelves and one hanging.

But the most exciting thing of all to me in this area is the ship’s office. This will provide a quiet place to work, or just read, separated from the working areas of the boat. We think we will be able to fit in a really comfortable padded office type chair that slides toward the desk when not in use.


The salon has the traditional arrangement of a drop leaf table and two settees.

By dispensing with the quarter berth, we were able to add lots of good storage outboard of the settees and on the port side we will have a transom berth, upper bunk (not shown) created by lifting the back of the settee, which will be hinged at the top, into a horizontal position.

This arrangement provides three really good berths at sea that will work well for a crew of four, since one person will always be on watch. The berths are just the right width, parallel to the centre line, and close to the centre of pitch. You can read more about what makes an ideal sea berth here.

Chart Table

“Chart table, I see no chart table?” I can hear you say. You see, chart tables in a boat this size are generally too small to be useful. So what happens in the real world is that navigation and planning actually happens on the salon table.

We have recognized that fact and provided a cabinet for surface mounting of instruments (connected to the equipment room with a cableway) on the face of the forward salon bulkhead to port of the mast support. (And If you don’t want to use it for that purpose, it will easily convert to a storage locker.)

This optional instrument cluster will also be a great way for the off-watch-skipper, or a single-hander, to keep an eye on navigation and sailing instruments from either of the sea berths, just by opening one eye.


The bottom line is that the best galley on an offshore boat, in port or at sea, is the classic U shape next to the companionway. No other arrangement comes close for safety and convenience. And we have a really nice one with three burner stove, double sink, and well insulated ice box that can be converted to a fridge freezer by owners that wish to.

We have also swiped some room from the huge cockpit locker to port to provide an additional locker for cutlery and flatware behind the sinks.


We now have a perfect head and shower, at least for a boat this size, situated in the best possible place. This area will also double as a place to dry foul weather gear that actually works, unlike the silly lockers supposedly meant for this purpose that you see on most boats of this size (when the builder bothered to include this vital feature at all) that are barely big enough to dry a single life jacket…for a Pekinese.

The head itself is oriented the right way and in a fairly tight alcove of its own so you can wedge yourself securely to contemplate the meaning of life.

When showering the head can be protected from flying water with a simple curtain—soggy toilet paper is so yesterday.

Equipment Cabin

The shower also doubles as access to one of the best features of the boat: The equipment cabin complete with plenty of storage and places for owner fitted equipment. All of the plumbing and cable ways will terminate in this area that will also house the breaker panel and batteries. And we have a work bench with a vice.

(A small additional breaker panel will be provided in the salon on the bulkhead separating it from the head, for circuits that are frequently switched on and off, like those for navigation lights.)

The long term voyagers among our readers are now cheering…I can hear you from here. Unless you have experienced it, it’s really hard to comprehend what a huge increase in your cruising enjoyment having all the mechanical and electrical equipment—every pump, fridge compressor, batteries, water maker and its filters, chargers, etc—in one easily accessed space provides, instead of stuffed in every possible corner as they are in most boats of this size.

This area also gives great access to the back of the engine, transmission and drivetrain. Access to the front of the engine will be by hinging the steps at the top and providing lifters to hold them in the open position.

The equipment cabin will also be accessible via a hatch matching the one that gives access to the cockpit locker on the port side. This will provide ventilation and a way to get large or dirty equipment in and out without dragging it through the accommodation.

Cockpit Locker

To port there is a cockpit locker, that will be watertight and separated from the rest of the boat. This locker is huge at nearly 8-feet (2.4 meters) long and over 5-feet (1.5 meters) across at the forward end. It will easily swallow up the deflated tender, spare anchors, dock lines, fenders and all the other stuff that ends up on top of berths in most boats this size.

Ventilated Locker

The aft end of the boat is given over to a ventilated locker for propane, outboard fuel, and hopefully the outboard itself, separated by a vapour-tight and watertight bulkhead. This will also provide a space for owners that wish to (we don’t recommend it) install an under-deck autopilot driving a separate owner supplied tiller attached to the outboard hung rudder.

One More Thing

Equipment cabin

The work bench and all the shelving in the equipment cabin will be easily removable. The idea here is that owners that wish to can customize this area to their heart’s content, including a single bunk, or even a small double—Erik has shown one option in the plan above.

Not only would this be a great place to sleep at sea, it would also make a nice private cave for a child. Although you will have to train the little darling not to flick all the switches!

Now, in my opinion, taking out the work bench and cluttering up the equipment room with a bunk (or anything else non-equipment related) would be a major mistake.

But making the cabinetry in this area removable conforms to one of the basic tenets of the Adventure 40—that we will make her as easy to customize to the owner’s taste as possible—so I finally gave in when Erik suggested it…after a lot of kicking and screaming.

Just to be clear. We are not breaking the no options fundamental of the Adventure 40. Every boat will be delivered with the workbench and equipment racks installed. It’s up to the buyer to remove them and build in something else.


There is no gentle way to say this. If you are dreaming of a varnished wood interior fitted with lots of beautifully made drawers and clever and complex places to store stuff, the Adventure 40 is not for you. We simply can’t afford the labour costs of that kind of fit out if we are going to hit our price target and build a high quality hull, deck and rig too.

The interior will be mass produced outside of the boat in modules that are pre-finished, probably with some kind of plastic laminate. There will only be two drawers, both in the galley for storing sharps, etc. The rest of the stowage will be fitted with shelves—adjustable up and down would be good—and we may even resort to zippered fabric locker covers rather than doors.

I am hoping that we will be able to trim the edges of at least some of the cabinetry with wood by designing it all in CAD and then cutting it out on a CNC router. This will result in a light and airy feel, but with a touch of classic class, much like the traditional “Herreshoff interior” of white painted wood with mahogany trim.

By the way, I can tell you, having had boats with both types of interior, that the Adventure 40 will be much more pleasant to live in and easier to maintain and keep clean than some varnished cave.

With the exception of the head/shower module, there will be no fibreglass liners to add unnecessary weight, take up space, and restrict access to the hull and deck.

Light and Ventilation

The boat will have three big Dorade vents: one forward and one each over the galley and head. There will be eight ports: six fixed in the salon and two opening, one in the head and one over the galley.

There will be only one hatch, situated in the forward cabin. Yes, I know that many owners will want more hatches for light and air, but keep in mind that a white interior needs a lot less light to feel bright than a varnished one and a wind scoop fitted forward, together with the Dorades and two opening ports, will keep the boat plenty cool.

One thing we will do is to incorporate a flat area with no core into the deck amidships where a reasonably handy owner can easily install another hatch. A feature that would be in keeping with the easy to customize ethos of the Adventure 40.


We will provide plenty of hand holds so that you can move through every part of the accommodation without ever being in a position where you can’t grab a new one before letting go of the old.

But even better than that, if you look carefully at the interior, you will see that in every area there is secure cabinetry to lean on. You simply can’t fall far, because there isn’t far to fall. This will hugely reduce the risk of this all too common injury at sea.

There is a vital point to understand here: As anyone who has been to sea will tell you, becoming weightless as the boat goes over a nasty wave is common, even on a sea kindly boat like the Adventure 40. Now, if you are sometimes weightless it means that you will also pull as much as two gravities on the other side of the cycle. So, are you strong enough to hold twice your own weight on even two hands, never mind one? I know I’m not.

Think about that the next time you are below on a boat with one of those “light and airy, spacious interiors” and the sales rep reassures you by pointing at the single handhold rail (if any) down the middle of the deckhead of the cavernous salon—hand holds are good, stuff to lean on is better.


Erik and I are pretty confident in this interior design, particularly since we used input from the over one hundred comments to the original Interior Arrangement chapter. Having said that, no design is ever perfect, so if you have a better idea we are all ears.

However, before commenting, please do as I do before writing anything about the Adventure 40 and read, or reread, the Adventure 40 Core Principles post. It will take you less than five minutes and make your comments that much more relevant and therefore useful.

Like what you just read? Get lots more:

Meet the Author


John was born and brought up in Bermuda and started sailing as a child, racing locally and offshore before turning to cruising. He has sailed over 100,000 miles, most of it on his McCurdy & Rhodes 56, Morgan's Cloud, including eight ocean races to Bermuda, culminating in winning his class twice in the Newport Bermuda Race. He has skippered a series of voyages in the North Atlantic, the majority of which have been to the high latitudes. John has been helping others go voyaging by sharing his experience for twenty years, first in yachting magazines and, for the last 12 years, as co-editor/publisher of AAC.

213 comments… add one
  • michael f May 21, 2016, 1:49 pm

    As this may influence head location and therefore interior design, I was wondering where the holding tank would be located. I would hope for a gravity draining tank, and preferably a short run from the toilet directly to the tank, unless I learn why this is not advisable. If all through hulls are to be clustered in the equipment bay, how will the sewage overboard through hull be located to keep it aft of or opposite side of the intakes?

    • John May 22, 2016, 9:50 am

      Hi Michael,

      Erik is working on the plumbing layout at the moment. I agree that a tank that can empty by gravity is a great idea. The problem is that this requires having the bottom of the tank well above the waterline and that in turn means that a tank of any size would need to be hard up under the deck using valuable space that we need for other things.

      On the bright side, it does look as if the holding tank will end up right next to the head.

      And yes, we will have to think about the black water outlet in relation to intakes.

      • michael f May 22, 2016, 10:08 pm

        My experience and knowledge is limited. However, as a consumer, I would accept giving up space within the head compartment in order to achieve a gravity draining tank. For example, in the current layout, moving the toilet aft enough to place the tank behind (forward of) the toilet with the thru-hull directly below the tank. If toilet paper is protected behind a door outboard of the toilet, there would be no problem showering in proximity to the toilet. It seems like there would be a small space savings by reducing hose, valves, and pumps. Would that also eliminate a siphon break since the top of the tank is vented above the waterline?

        • John May 23, 2016, 8:20 am

          Hi Michael,

          I guess it comes down to what a person prioritizes most. Moving the head aft far enough to get in a holding tank is certainly an interesting idea with benefits, but on the other hand it will make the head/shower a less usable space and result in some impingement on the shower space. A door outboard of the toilet will not, I think, be practical because of swing interference. We already have two doors in that area, add a third and it’s going to be a real puzzle, door swing is surprisingly difficult to get right.

          Having said that, it’s worth thinking about.

  • Chris Jul 3, 2016, 5:52 pm

    First off, let me say that I have zero sailing experience so you may feel free to discount any of my opinions, they are not supported with any real world knowledge. 🙂 My experience was on working boats, mostly in the oil industry, but I’ve also gone out on a Frigate during sea trials. Good fun, as long as you don’t mind chasing the worst seas in the North Atlantic.

    I am only recently became interested in live aboard cruising, and my look at current production boats was discouraging. Lets just say that most are designed by an interior decorator and not by a naval architect. The worst seem to be going for the Scandinavian furniture look and have not installed any stowage in an attempt to keep the walls open, light, and airy. Very nice, except that I can’t unpack my skivvies. There are a few brands that make what look like nice boats with traditional interiors and a better setup for cruising, but they are still very expensive, very complex (electric everything), and still fat arsed.

    My situation is as follows. Wife, two kids (4 and 2), and not able to carry two mortgages. That means that I can only afford a boat if I live aboard and dump the house. That actually appeals to me as I feel the house is more than we need. I just want a double bed, two bunks, and some settees that convert to sea berths. Unfortunately, the mass market boats don’t go for bunks until you get large enough that they expect you to set sail with hired help. Here is the bunk for the cook, one for the nanny, and one for the hire skipper.

    The A40 is design awesome and currently lacking in the market place. Thank you for doing your best to address it. Any way that you could see a family of four squeezing into this size boat for more than just weekend cruising? Obviously it won’t be a three cabin boat, but could it work? If not, what sort of displacement would you consider the minimum for a small cruising family (live aboard cruising along the US east coast and Caribbean?

    Keep up the great work. I am very much interested in the concept. I just hope that I don’t need to wait for an A50.

    • Marc Dacey Jul 3, 2016, 10:46 pm

      A very good comment and you are far from alone in both your opinions and your ambitions.

      • Chris Jul 4, 2016, 12:30 am

        Thanks. I wonder if there would be enough vertical height for the owner to replace the starboard settee with a set of two built in bunks. That reduces the table space, but my whole family rarely all sits at a table to dine anyway. I usually eat standing or at a counter.

        The top bunk might even be made to pivot up to allow seating below. Though I would want to avoid dual use sleeping arrangements if possible to avoid the daily chore of making up beds and the putting everything away again.

        • John Jul 4, 2016, 7:14 am

          Hi Chris,

          The boat will come standard with a transom berth, see the text of the post above.

    • John Jul 4, 2016, 7:13 am

      Hi Chris,

      Thanks for the kind comments on the A40.

      While the boat is primarily designed for a couple with occasional guests, whether or not she would work for a family of four, is more about you and your family than the boat. There are certainly enough berths and storage, but it does mean that even if you install a pipe berth in the equipment cabin, one of the children will be sleeping in the salon in the transom berth (not shown). Is this acceptable? Only you and you family can decide. I can say that many families of four have managed in boats as small, or even smaller than the Adventure 40. Dave and JaJa Martin come immediately to mind and they have three children. You might want to get their book.

      As you say, a three cabin boat would be preferable, and to get that, and still have decent storage, you need to go up to about 24,000 pounds displacement.

      Maybe the best thing for you to do, would be to charter a boat of about the same displacement as the A40 and see how it feels.

  • Maxime Gérardin Apr 14, 2020, 5:37 pm

    great interior layout indeed.
    However, doesn’t it put much more weight on port than on starboard? Or this could be solved by putting the windlass and chain on starboard? But it seems even more tricky on that side of the boat.
    By the way, where do the batteries go? And if we go quite low-tech, shouldn’t we see the service battery as a mere windlass battery, and choose its place accordingly? (I apologize if this has already been adressed)

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