Twenty Two Adventure 40 Core Principles


As I was reading through the existing posts on the boat to get myself in the Adventure 40 mindset, it struck me that sticking with the core principles that govern the boat’s design is actually quite a challenge, even for me who conceived the boat in the first place.

So I resolved to write a cheat sheet to make sure we all stay focused on what we are going to achieve with this boat:

  1. The Adventure 40 is an offshore voyaging boat. Everything else will follow from that.
  2. The boat will be fast, and comfortable when going fast.
  3. The boat will be designed to be optimized to be sailed—this is a sailor’s sailboat, not a motorboat with a large flag pole.
  4. The boat will be as safe offshore as we can make her.
  5. The goal is low ten year cost of ownership, not a low sticker price.
  6. The boat will be optimized for being on the anchor, rather than in a marina.
  7. We are aiming at a ready to sail away price of US$250,000.
  8. The boat will be trouble free for at least ten years with only routine maintenance required—quality control trumps all.
  9. The boat is designed for a couple to live on and voyage, possibly with a child or two. It will be possible to have guests or crew for a passage but they probably won’t stay long.
  10. Storage is more important than the number of berths.
  11. It is always better to have a few usable spaces, both below and on deck, than a lot of cramped ones just to tick someone’s “I want” box.
  12. Simple and elegant will always win over complex, even if the simple answer involves some inconvenience.
  13. The boat will be built super-strong and forgive mistakes like running aground.
  14. There will be no options. Every boat will be identical when delivered. Buyers will not even be able to specify that a piece of standard gear should be left off. However, you can have the boat in any colour you like…as long as it’s white.
  15. The builder will provide gear as standard, like winches and chain plates for a Jordan Series Drogue, that would be difficult and expensive for the owner to install.
  16. We will make the boat easy to customize and add gear to: Mounting space, cable ways, spare breakers, places for additional seacocks, etc.
  17. The boat will be delivered with no electronics. The last thing the builder needs is to be distracted by 50 new owners with software problems with the latest whiz-bang plotter.
  18. The boat will be delivered with a robust engine and basic electrical system. No other mechanical or electromechanical gear will be provided as standard, although provision for adding things like refrigeration and watermakers will be made.
  19. We will spend the money on great gear, rather than a lot of gear.
  20. Nothing will be fitted to the production boats that was not exhaustively tested on the prototype.
  21. No gear will be fitted to the boat that has not been in general use for at least ten years, and twenty would be better.
  22. Wants won’t make it onto the boat as delivered, but all the needs will.

The Adventure 40 is not an “all things to all people” boat. And we will never succumb to the temptation to make it one just to make a sale.

Or to put it another way, the default when faced with “unless you change this I will not buy” will be “well, I guess this is not the boat for you”. We would rather build a few great boats than a lot of lousy ones.


If you have any questions about the above, please leave a comment. Ditto if you think I have forgotten something, which is quite possible given the complexity of this project. But before you comment, please read, or reread, the summary post as many of the points above are explained in depth there.

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Ray Dunn

Thanks for the update, John- I don’t think you are being arrogant, and this is one of the better posts you’ve written on this topic in a while (at least for me), and I appreciate the simplicity with which you are approaching this project. After going through enough trials on my current boat retro-fitting a number of systems for single-handing I appreciate you letting the eventual owners of this boat customize on their own and I think it will be fun. I look forward to the posts when the prototype gets to the sea-trials.


Martin Burnett

I still think this is a great idea and a i am willing to help in any way possible. looking forward to any posts that you make GO For It John

Chris Terajewicz

1. Will be interested in safely single handing the Adventure 40. This means deck plan and sail plan that can be safely managed from the cockpit.
2. Sea berths in main salon are a must.
3. You won’t design around me, but I’m 6 ft 6″ and will need a long sea berth.
4. Headroom down below is important to me(as close as you can get to 6’6
5. Please pay lots of attention nav station layout and workspace
6. Deep keel ?

Nathaniel Montague

I know that maybe I am just opening up a can of worms, but why are you not considering a cat ketch rig? If you want a vessel that fits everything you have just listed above including, speed, comfort at speed, gear that has been in use for 10+ yrs (try 35), and simplicity and ease of handling, that is the rig to use. Your emphasis on safety? With considerably less weight aloft you will be able to design a boat which could (although hopefully never would) roll to a turtle and actually be able to pop back up relatively quickly. When discussing seaworthiness of a full-time cruising boat, the amount of time expected to recover from a roll should not be overlooked as that length of time means the difference between survival or drowning.


I’ve owned and sailed sloop and ketch rigs. My present yacht is a Pearson 424 ketch here in the trades of Hawai’i. Easy to handle in a boat of this size, I love the flexibility and choice of sail plan with a ketch rig and will probably never go back to a sloop.


Looking forward to the deck and rig post. Happy to see matters are moving along.

As I sit here looking at a bunch of fat-assed Beneteaus, Catalinas, and yes, even Sabres, there has to be a better alternative available.

Best regards, and carry on, promptly!


George M

I agree with all the points except that I think number 9 needs a clarificatory remark. It is true that in harbour a few big spaces are preferable to lots of cramped ones. However, at sea wide open spaces above or below deck are dangerous. The trick is to design a boat so that it appears large when in fact it is snug and cosy enough to be safe at sea.

Another thing I have been thinking about is intrinsic flexibility. Two of the boats my father has had have had a neat arrangement in the forecabin that allowed that cabin to be converted from one large double to two smaller doubles when needed. Were one to build the A40 as standard with such an arrangment (and there is enough space on the A40 to do this, I have checked.) one would significantly increase the appeal of the boat without having to offer a whole bunch of options, or decrease its desirability as a couple’s boat. One could have the best of both world for little extra cost.

This is also why I like the idea of Pullman’s berths in the saloon. With very little extra cost and no errosion of stowage one gets a boat with 4 perfect sea berths instead of just 2. This hugely increases the flexibility of the boat for very little extra cost.

George M

Sorry for the drift. Just thinking out load. Its a hazard of my profession; the need to write things down to get your ideas straight. I’ll try to keep my powder dry in future.


I missed the early discussions. What predicated the choice of limiting LOA to 40ft ? It certainly makes Rule #2 difficult to achieve.

On reflection, I think a lightweight, easily driven 60ft with no more “stuff” on board than the 40 footer would be easier to design and build. Maintenance would be a joy. And Rule #2 will indeed rule!

But then, of late, I find myself becoming a Dashewite.

Stephan Hamann

Hi, to the whole community!
I am following the post just for a little while and I goes you are bringing my thoughts of an ideal cruising boat to “paper”. But maybe I am a unicorn in that community as well as being from Germany.
So an important question for us, a couple with a small daughter, where will the boats being build? I know there are a number of good manufacturers here in Germany as well. Close by is the old Dehler shipyard is not to far.

An secondly, did you think about the regulatory framework such as CE-marking of the boat for all those European folks interested in that design?
Many thanks for your thoughts and I would be willing to help where I can to make the project happen!

Stephan, close to Cologne

Stephan Hamann

I know that the old Dehler shipyard is closed but a new one with a number of the old boatbuilders under new management formed a new company on the same infrastructure.
If you like, or if it is okay with you, I will try to get in contact with these people and investigated whether there is interest on such a project at all.
Best regards,

Dick Stevenson

Why 2 lights on the leading edge of the mast (is that a European convention which I have seen but never understood). One I would see as steaming. Is the other a deck light and the diagram just shows it shining forward? And there look to be no side lights (stern light may be there, hard to tell) which caught my attention because the other lights are so nicely displayed. Also, it may be confusing, going forward, to show radar if you are not planning to include it in the delivered boat.
It looks really nice.
Dick Stevenson, s/v Alchemy

Erik de Jong

Hi Dick,

Those lights drawn represent the regular lights you find on all boats. Nothing European about it. A vessel has to comply with “COLREG”, and that is the same throughout the world.
The unconventional thing about the arrangement that I usually advice on, is that the red-green sector light (that is usually on the push-pit) is on the mast as well. In my opinion a much better place than on the bow for several reasons:
1. It is higher above the water, so visible on a larger distance, and does not get out of the line of sight from other vessels in a swell either.
2. Less prone to damaged lamp glasses due to stepping on the boat, bumping into something etc.
3. Significantly less maintenance, as the lamp does not get submerged underwater anymore.

I agree on the radar, should not be shown on the final drawings as it will not be part of the delivery.

Thanks for the sharp eye!

Erik de Jong

Hi John,

Good arguments.
I have used this setup on Bagheera since I constructed her, and I’m very happy with it. The reflection is not bad at all, although I must admit that I barely ever have a headsail up when running these lights.

An obscured light by a sail would also be obscuring the white light that needs to shine at the same time when motoring along. So the problem is there in any case.

I actually stop moving at all when the fog is so thick that you can only see the other vessel so close that they have to look really up before they can see the masthead light. But you are right, not very applicable for most potential A40 buyers I assume.


I commend how, in answer to design queries, reference is made to a particular number of the stated principles. If it was not already your plan, I suggest that you fix the individual numbers, and keep referring to them when debates about design details and choices arise in future.
If you have to adjust the original set of principles, which is possible, a number can be removed and a new one added. (Apologies if this approach was already explained and embedded).
I would expect that few commercial sailboats would be developed by sticking to a limited set of non-marketing related foundation principles like is being done with the A40. They give welcome transparency to the detail design process.


Hi John,

Regarding n.12 even a carbon fibre mast option will be out of consideration?

George M

On the options point 12 again. My point about intrinsic flexibility in the interior also generalizes to all aspects of the boat: the rig, the draft, the engine, etc. Its great to do an options free boat but the intrinsic flexibility of the design should be as great as is consistent with the boats mission. A boat with no options and narrowly targeted will have a limited customer base, one with no options and a good deal of flexibility built in will have a much wider customer base.

Sandy Stephen

Hello John, (all)

I’ve been following the Adventure 40 project for some time now. Your design methods and ideas remind me of a video I recently watched on TED.
The leadership and the respect you show to others (ideas) are driving this project into reality.
Being a late starter into the sailing world, it gives me great peace of mind to have so many experienced people behind this boat. The core principles are spot on. Looking forward to the next posts.

Keep up the good work,


Do you have a target launch date for the prototype John?

Andy Nemier

I’m literally waiting for the Deck & Rig info ,,,
(like a child at Christmas ; )


No electronics…. Does this mean no speed transducer (log) and depth transducer, so we have to drill in our perfectly new boat to place our transducers of choice? It seems to me that these are elementary instruments, though I think that the transducers will be manufacturer specific, so that it is a catch 22?
A boat ready to sail would include at least depth, speed, wind angle /speed instruments is my thought.


Hi John,
Thank you. Yes, I think a fillet would be great. “Problem” solved I think. 🙂

John Frazee

Tankage, tankage, tankage. You can’t always get fresh water and you will certainly be places the water is too dirty to make water.

Let us not forget that the best offshore boat is still just transportation to the destination. At sea it is little more than a bus. The boat must also meet the needs of the 80% use, that being sitting at anchor at your destination. Few of us just go sail on ocean passages without a destination. What works for the days at sea may be impractical for the months of anchoring. I would rather be inconvenienced for 10 days at sea than 6 months cruising at my destination. Also design with dinghy use in mind. It has to go with you on the ocean and be convenient to use at the destination. No one sails to a destination with no plans to go ashore. Finally design in the ability to add solar and wind to provide the necessary power to live aboard while cruising.

John Frazee


Here is our list of needs in a boat. We have been spoiled for 4 years of cruising on a 42 foot cat but the cost of cat cruising is quite a burden and we are considering a monohull as a replacement. This list is the result of both my input and my wife’s. We are in our 60’s and that colors some of our comments. The list is by priority.

Ease of dinghy access and storage. If you can’t get off and on a boat at anchor what good is it? This one requirement shrinks the list more than any other.

Comfortable and dry cockpit long enough to relax and sleep in. Who wants to sit in the rain. This is where the cat really shines. In the last 6,000 miles of offshore sailing we have never had to put on foul weather gear.


Galley convenience.

Alternate power source handling ability. This includes adequate battery storage space.

Separate shower

Adequate storage in both refrigerator and freezer. We are no longer backpackers and food gets used every day.

Bulk food storage in an accessible location.

Ease of reefing. You must be able to reef by one person in the dark easily. Offshore your crew does not know the boat the way the owner does and nothing bad happens in the daylight.

A keel designed to keep the boat going in a straight line offshore. Hand steering for 1,500 miles loses it’s appeal after the first day and an autopilot or self steerer that keeps hunting soon wears itself out.

Pleasing to the eye. Who wants to sail an ugly boat?

These are our no compromise items. It sure narrows down the list of available boats

Stephan Hamann

as I said,
I contacted a shipyard here in Germany, the former Dehler Werft, now called SQ Freienohl.
They do have interest in building the Adventure 40 and I summarized quite some infromation for them in order to allow a first calculation in building a prototype, somewhat a One-Off. More I woud be pleased to tell not in that public round.
Can we please have some kind of a side conversation how to move on with theses guys? I assume it might be good at one point in time to have a discussion on the phone or face to face would even be better.


Stephan Hamann

do you have something like condensed Design Input Specifications that I could provide to the shipyard in order to allow them to make a valid calculation of the building of a prototype /moulds for the series / etc?

Marco Lupieri

Hi John, Marco from Italy here.
I’ve been following the A40 project since its very initial stage, and possibly read all posts. However, I can’t recall any mention to interior air circulation, for those who intend to sail in warm waters…what about dorade ventilators, for instance?
Keep going!

Andy Nemier

Hi John,
First of all,,, great work to Eric & the team for another fantastic effort. I ‘ve been sitting on my post, as I feel ‘if you have nothing positive to say,,,’ However, I see the boat has grown yet again. At 40′, I was all over it. At 42′, I talked myself into the benefits, but at 45′, you’re losing me. I simply want a smaller boat, less = more. Am I alone with this thought? I thought I’d ask if this LOA was now firm?

Dick Stevenson

Erik, Thanks for the explanation. I think having the sidelights on the mast well below the steaming light is brilliant and makes perfect sense for all the reasons you describe. Dick


John, I have been thinking about your principle #12: no options.

As a general rule, it’s great. Interior layout variations hugely complicate the construction process and add to costs. Items such as electronics present a warranty headache for the builders, and are best left to the aftermarket. So minimising options is a great idea.

But zero options? That seems a bit extreme, because some options can surely be offered without messing up production schedules or raising warranty hassles … but denying them could cost sales.

Here are some examples which occur to me:
* Hull colour. A coloured gelcoat just requires a different mix for the first stage of the layup. Aside from choosing a different tin, no extra or altered work is involved.
* Presumably the boat will be supplied with berth cushions. In a back-to-basics fitout, the colour and fabric of the coverings will have a significant impact on the ambience of the interior, and are a simple way to personalise the boat. Choice of these loose items raises no significant warranty issues or production hassles, but lack of it could be a deal-breaker for the female half of couples to whom the boat is marketed.
* Carbon masts may be a good idea or a bad idea, but again have almost no impact on production. The spars will be shipped shrink-wrapped to the customer; so if someone wants to spend an extra $10,000+ on a carbon mast, why not let them?
* Same with sails. There are arguments for and against several different sailcloths; why not give the customer a choice of what’s in the sealed bag?
* Bow pulpit styles vary according to use; e.g. walk-through pulpits are preferred in Scandinavia. Choice could easily be be offered there at the design stage, so that various options share the same mountings.

There are probably many more such choices which can be left to the customer without complicating production, increasing costs, or risking warranty hassles. Managing such options would be trivial; why take such a firm stand against *any* choice?


Just curious, why didn’t you choose an aluminum hull? I have not read all the pages so please excuse my possible ignorance if the answer is in those unread pages. Regards, Craig.


While accumulating the knowledge offering on this site and having covered the sections on drogues and anchors I had to come back to the core principles in this section to verify whether you are walking the talk. I was very surprised to find the Jordan Series Drogue specifically mentioned in core principle 13! I could now safely assume that there will be 2 oversized high quality anchors (Rocna and SPADE) included in the sale, not to mention the third aluminium anchor! Not only that it will be beautifully stowed. I still have a lot of reading ahead but so far the inventory on the Adventure 40 is looking better and better albeit by assumption. The only problem is that my expectations are being raised bring the hope that there will be no disappointments later.

Stein Varjord

Hi John.
I admire your ability to keep the cool and answer politely even when people question the properly discussed core principles of your “baby”. 🙂

As you may have noticed I’m completely lost to the light and fast multihull side of things, so I will not be a customer, but I find the process of development and the principles or “philosophy” very interesting, so I intend to dig more into it. I think there is much to learn for any boat development project or any buyer of a boat.

I think all the 20 points are good ones. My answer to them would be a completely different boat, but that doesn’t mean I disagree on the principles. as I come from extreme multihulls, my take on very thoroughly tested solutions and having been out there for preferably 20 years or more, is also quite different as we tested very exotic stuff long time ago.

Points 12 through 17 I think will be essential for achieving a consistent high quality at a low price point. The number 12 alone might be flexed in some strictly limited ways though. I would say that interior “software” like mattresses and textiles might be left out of the basic delivery, to let people have the opportunity to make that their own design.

The interior feel has a massive influence on the decision to buy even a serious boat, like this one. I think some buyers will then make all this themselves and others will use subcontractors suggested by you. These items will not affect the secondhand value of the boat type, as it is so easy to update in a secondhand boat too.

Probably there will be several topics similar to this one. I would suggest letting the standard (non alterable) delivery be as minimal as at all possible. Install only the items that influence the core values of the boat. Those items that an owner or a subcontractor should not be trusted with as it may affect the secondhand value of the boat type.

I would also not allow different gelcoat types or any other alteration to the main structures. I am a very firm believer in carbon masts however, so personally I’d say they are an improvement that is easily worth the added cost. I’ve had about 20 masts come down on boats I’ve sailed. Mostly racing masts, but still gives some clues and an ability to predict it some times. I’ve seen ridiculously light high modulus carbon masts (Marstrom 15 metre/50 foot and 42 kilo/92 pounds) do the most extreme type of bending and survive it undamaged, and seen the same boat kill alu masts 3 times as heavy in way lighter challenges.

Still I would also have only one rig alternative. With two mast alternatives, you could use the same chain plates etc, as loads would be lower than with an alu mast, but building a carbon rig and building an alu rig, even when not thinking of the tube itself, are two entirely different types of work. If this should be treated as an area of options, I’d say you also need to outsource the whole rigging. No matter which type the customer will choose. I’d say have one alternative only.

I assume I’ll find more topics I can’t resist commenting. I hope not to be too annoying, but can’t promise I won’t be. 🙂

Stein Varjord

Hi John.
My comment on carbon mast was mostly meant as a study of why I agree with the very strict “no options” policy outlined. I’m also not at all an educated engineer, just a hands-on guy that had to get an understanding of the loads to make things work while staying ridiculously light for racing. Thus I should try to restrict myself, but a few words may be useful. (If I say the phrase “a few words”, all who know me will laugh…) 🙂

You are of course totally right that a lighter total rig weight will make the boat more stable, heel less and thus generate more power. This difference is noticeable without very exact instruments, but is still clearly not the main advantage with a carbon mast.

The above observation is about static loads. The maximum loads on the rig, chain plates, etc, do however come when the static loads are high and then dynamic loads are added on top. This can more than double the total load. So the chain plates, sheets, etc need to tolerate short bursts of tension that can easily be twice the max righting moment of the boat.

These dynamic loads are very complex and it’s impossible to calculate and predict them entirely, but the main factors are inertia of the rig and sails and relative wind speeds when flipping to and from. Inertia is the big one.

If using carbon instead of aluminium, a realistic weight reduction in the tube alone might be 40%. Much lighter is possible, but will need more expensive carbon types. The removed weight in the rig will thus amount to something much more significant to the boat behaviour than two guys standing at the bow, since the distance from the rotational centre is much bigger.

The reduction in inertia of the rig, thus the dynamic loads, will be reduced by more than the static loads will increase. The peak loads on the rig and chainplates etc will thus be considerably lower with a lighter rig, but no redesign will be necessary.

As one mighr have guessed, a speed addict like me must love carbon masts. Still, I’m not so sure it is a good choice for this boat. It will disintegrate the price goal of 200 000. It may not appeal to the market segment this boat is made for. It’s harder to find qualified people to repair a broken one, even though the job is actually at least as easy as with alu and the result is better. I’ve done both. The most important:

The sail track is not always trouble free. If made in carbon, it’s very strong, but still more vulnerable to abrasion and damage from being hit. If a metal track is used, a bit of weight advantage is lost and we got a combination of materials that might be perfectly good or might develop galvanic corrosion or other stuff. I would not use a carbon mast tube until I felt this problem was bullet proof.

P D Squire

Dingy part of the spec.

I agonised over this comment before posting. On the one hand dingys could be seen as a personal choice informed at least somewhat by one’s intended cruising area. However, the A40 is a beginner’s boat and beginners mightn’t know their requirements in advance. There are basic jobs that a dingy must do i.e.; carrying people, supplies, & equipment; traversing motor-boat wakes and a modest shore-break without swamping; and being storable both offshore and coast-hopping. For offshore work and coastal hopping in foul conditions the dingy needs to be stored where the sea can’t dislodge it. When coastal hopping it needs to be easy and quick to launch and retrieve. In both cases it must not harm sightlines including sightlines to floating debris & pot-markers etc. Beginners cannot be expected to be able to solve these storage problems and it seems the only way they could be solved is to have a particular dingy in mind at the design stage.

I appreciate that the budget is tight but I think a standard thought-through and planned-for dingy should be included as part of the standard inventory in a fixed-keeler that draws 6’6″ and is NOT intended to marina hop.

If the budget can’t stand it, the design should certainly be optimised around a particular dingy that beginner sailors can be confident is large enough for their needs (not all “wants” but definitely needs), and stowable safely without harming sight lines.

The dingy is a vital component of a cruising deep-keeler. I agree that sophisticated electronics and many of the other items a boat-show salesperson would argue should be included needn’t be included in the A40. However, every A40 will need a dingy. My feeling is, like an engine, it should be included. If that’s not affordable then the dingy should surely be considered right from the beginning of the A40 design process to ensure it’s stowage & deployment aren’t afterthoughts, and especially aren’t left to the unintended-consequence riddled imaginings of beginner sailors.

Mark Wilson

Reading this and having agonised about this subject at length my takeaway is that it is just as much about getting the cockpit lockers right as it is the dinghy.

Voluminous lockers are important but some system of adjustable segmented compartments within would be good. Otherwise you end up with a pair of glory holes.



P D Squire

Fairly argued and I think we mainly agree anyway. I certainly agree it warrants an article of its own and look forward to it and the discussion.

Perhaps here in the “Core Principals” section we can say that as a low-total-cruising-cost vessel, the A40 will be optimised around anchoring and dingy use over marina berthing. In the dingy article we can sift through the specific dingy needs and wants.