Adventure 40 Hull Specification

The McCurdy and Rhodes Custom 38 Selkie

The McCurdy and Rhodes Custom 38 Selkie, is just about the same length and displacement as the Adventure 40. Photo, kindness of Ian McCurdy. (Don’t worry about the big overlapping genoa, this post is about hull forms, rig is another post.)

This post was originally written months before Erik designed the Adventure 40 but it is still worth reading because it defines the goals for the hull form that we are working toward.

#1 Sea-Kindly

The number one criteria for the Adventure 40, that will trump all others, is that she must be sea-kindly. Why? Because this is a boat to cross oceans, not sit in marinas. And if she is comfortable offshore, that single attribute will contribute more to a successful and enjoyable cruise than all the wiz bang gear and condo-like interiors in the world.

So what does sea-kindly mean?

  • No pounding when going to windward or close reaching. Until you have been offshore in a boat that pounds you can’t believe how horrible the experience really is. If the prototype Adventure 40 pounds I will personally take a chain saw and cut the bow off so the designer can try again!*
  • Comfortable pitching motion. I know, it sounds like an oxymoron, but it can be done with the right buoyancy in the ends, including reserve buoyancy, and the right distribution of weight in the hull.
  • Comfortable roll motion. A boat with too much or too little stability, both ballast and form (or the wrong combination), will throw you around mercilessly when the inevitable moment comes that you must motor in a flat calm and leftover sea or when sailing downwind. The Adventure 40 won’t do that.

#2 Fast

The Adventure 40 will be fast. Why is that important for a cruising boat? Because speed is one of the biggest contributors to safety and enjoyment offshore that a boat can have.

An Adventure 40 sailed by a middle aged couple will be able to make Bermuda in under five days in most any conditions, short of near-gale or more on the nose. Contrast that with a dumpy boat of the same weight that would take at least six to seven days to make the same passage. And then only if the wind does not go forward and she does not need to heave-to. In the more likely scenario, where one or both happen, the dumpy boat could be out there taking licks for two weeks or more—it happens every year.

Let me illustrate what a truly fast offshore boat is with an example: In the 1994 Bermuda race, if memory serves, eight boats from the drawing boards of McCurdy and Rhodes placed in their respective classes. This was no fluke. Last year Carina won the race for the third time. Over the years McCurdy and Rhodes boats have won silver in the Bermuda race with a far, far higher frequency than the percentage of those designs entered in the race would lead you to expect.

What’s happening here? How can these boats consistently beat boats that are much younger, more modern, and theoretically faster in a straight line? Simple…when the going gets tough the sea-kindly boat keeps going, while the more modern competitor is reefed and slowed down because the crew can’t take the violent motion and pounding. And that’s with tough racing crews aboard. Imagine the effect of the same conditions on a cruising couple.

And it does not take a gale to make this happen either. In just 20 knots of true wind forward of the beam, the crew of a sea-kindly boat will have the pedal to the metal and be having fun, and probably eating a good cooked dinner too, while the boat with a U-shaped bow and flat sections forward will be knocking its crew’s fillings out. Trust me on this, I have raced to Bermuda on both types.


In my opinion, when these large flat areas start to connect with a short steep Gulf Stream or Bay of Biscay sea, the fun is going to go out of sailing on this boat in a big hurry. Not only that, although an owner of a sister ship to this boat assures us that she is too strong to be damaged by sea action (see comments), the pounding can be so bad that there will be a real possibility of significant structural damage on other boats with this hull form. We blew the bulkheads and furniture right out of a boat shaped like this on one rough race to Bermuda. Oh yes, and get five gallons of water in a shallow bilged boat and you will be living with it…in your bunk.

I can hear many of you saying “wait a minute” most cruising takes place on downwind routes, so why this emphasise on a boat that sails well with the wind forward? Three reasons:

  • If the true wind is on the beam, or even slightly aft, of the beam, the apparent wind will be forward due to the boat’s speed. And beam or close reaching—which happens offshore more than you might expect, due to the above fact—can be even more brutal on the crew of a boat that pounds than being hard on the wind.
  • Yes, most of a round the world cruise will be downwind, but sooner or later things won’t go as forecast and you will be on the wind for two or three days, and when that happens the hell of being on a boat that is not sea-kindly will outweigh months of idyllic downwind sailing.
  • A boat that sails well upwind will almost certainly be easy to steer, comfortable and quite fast enough, for a cruising crew, downwind. You can’t say the same for the opposite case.

This hot racing boat would blow the doors off an Adventure 40 in a down wind race, particularly with a tough racing crew aboard. But put two Mom and Pop crews on the boats and send them off from Newport to Bermuda, a passage where the wind is likely to be from forward of the beam, and I’m betting on the Adventure 40. And even if the Adventure 40 loses, her Mom and Pop will keep going round the world. The Mom and Pop on the boat above will be buying a farm in Nebraska.

#3 Easily Driven

The Adventure 40 will be easily driven, meaning that the short handed cruising crew will be able to keep her going fast and comfortably without having to:

  • crowd on a bunch of sail,
  • reef and un-reef for every slight wind change,
  • sail the boat at heel angles over 25 degrees when close reaching or beating,

like you would have to do in lighter and more extreme boats.

By the way, old heavy boats can be hard to sail too. My old Fastnet 45, designed in the sixties, needed high heel angles and frequent sail changes to keep moving. She was also really twitchy to steer.

#4 Easy to Steer

The Adventure 40 will be easy to steer with a wide groove going up wind and down, and little tendency for the helm to load up when she heels. She will also be able to broad reach and run in big breeze and waves without broaching.


I can hear some of you now. What about safety? What about stability? And of course you are right, that stuff is vital. But I have not got into those areas in this post simply because, in my experience, boats that satisfy these four basic criteria are both stable and safe.

Can It Be Done?

So, all of this seems like a pretty tall order. Can it be done? Sure, I have sailed a boat that has all these attributes for some 20 years and 130,000 miles, our own Morgan’s Cloud.

Let’s look at some of the things that make her hull great for offshore:

  • Just enough V forward to prevent pounding, but not so much that she locks in and bow steers when running hard in big seas.
  • Just enough flare and overhang to provide enough reserve buoyancy to retard pitching and keep the deck dry.
  • Just enough turn to the bilge to give her good form stability, but not too much, which would make her cranky.
  • Moderate beam tapering to fine ends for sea-kindliness, but not too narrow, which would make her initially tender.
  • Symmetrical ends so that the helm does not load up when a puff hits.
  • Hull form that can carry the weight of cruising gear and provisions with little effect on performance.
  • Deep enough hull that the tanks for fluids can be under the cabin sole, rather than taking up valuable room under the bunks.

In summary: moderation in all things.

Don’t get me wrong, I’m not saying that the boat must be designed by McCurdy and Rhodes. Also, I’m not implying the Adventure 40 will be a small Morgan’s Cloud. 

I’m well aware that naval architecture has made huge strides forwards (and some back) since the hull and appendages of our boat were designed back in the seventies, or Selkie’s in the eighties. And I fully intend that the Adventure 40 will take advantage of those advances. For example, replacing Morgan’s Cloud’s keel, with its sharpened lower edge, with a modern keel would make her more close-winded without increasing her draft.

Adventure 40 Manifesto

So here is the bottom line: The Adventure 40 will be designed with an absolute dedication to seaworthiness and sea-kindliness (the same thing, really). No criteria will be allowed to intrude into the specification that will have any negative effect on the attributes detailed above.

That means that the hull form will not be influenced in any way by the need to shoehorn in a particular interior layout or a bunch of equipment. And that single commitment will make the Adventure 40 a better offshore cruising boat than most anything out there on the market.


I’m pretty comfortable with the contents of this post, which has also been checked out for technical accuracy by a real naval architect. Having said that, if you have comments, questions or suggestions, I’m all ears.

* OK, there is a bit of hyperbole here. But I’m serious that an Adventure 40 that pounds will never see the light of day, at least not with me involved.

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.

45 comments… add one
  • C. Dan Sep 30, 2012, 2:47 am

    Enjoying the manifesto and can’t wait until you’re ready to take my 10% deposit.

    Keep it coming!

    • John Sep 30, 2012, 8:44 am

      Hi C. Dan,

      Thanks very much for the vote of confidence. Someone ready with a deposit is the ultimate validation of the boat.

      Just to clarify, we (AAC) will not be taking deposits. Rather that will be the builder’s role. We are the facilitators here.

  • Viv and Mireille Sep 30, 2012, 7:56 am

    Sea kindliness, could not agree more! Having done the NY-Bermuda run many times I always remember one boat in particular. It cost nearly a million (used) built beautifully but pounded to windward like a kettle drum, horrible ride. The forefoot was literally flat from the keel to the bow intersect. It was very tiring and being 51′ was a lot of boat to manage with a small crew.
    I was in favor of a sled-type hull in the past but that was to do with just enjoying speed and racing inshore, not serious ocean cruising. I agree with all that John has written. For serious offshore sailing, crew comfort, therefore safety, is paramount.
    I like the Pedrick design (the Navy 44) and of course M&Rs

    • John Sep 30, 2012, 8:49 am

      Hi Viv and Mireille,

      Thanks very much for the vote of confidence. It means a lot coming from someone with your experience. I always admire delivery skippers. In my opinion, there is no tougher way to go to sea, or quicker way to learn about seaworthy boats.

      (For those that don’t know him, Viv made his living as a delivery skipper for some years.)

  • Martin van Breems Sep 30, 2012, 8:35 am

    This is full of incorrect or misleading statements, which discredit your basically sound idea’s. For example, Pedrick did not design the Navy 44’s – he designed the Morris built CG 44’s, which are more advanced boats.

    I also own a Hanse 400, which you have used as a pic for a un seakindly boat which falls apart. Hanse, esp going back, are astonishingly strong boats, with bulkheads fibreglassed, not glued, to both the hull and the deck. The issue off shore with many production boats is not the design itself (although the beam is pushed too far forward with too small rudders, etc on way too many). The construction is often not stiff enough for extended offshore trips. I used to be, but have resigned as a dealer for Hanse, mainly due to other time committments from my 3 other businesses. However, after having sailed my Hanse 400 every year from CT to St Thomas in Nov or Dec since 2006, and back in the spring, I am amazed how solid and seakindly these boats are.

    • John Sep 30, 2012, 9:04 am

      Hi Martin,

      Thanks for the defense of the Hanse 400. You obviously know a lot more about the boat than I do, so that is valuable. I have modified that caption to reflect your input.

      However, I still stand by my assertion that boats with this kind of hull form risk structural damage due to pounding, even if the Hanse is so well built that she will not. For example, the boat we broke up in the Bermuda race was from a very reputable builder.

      Also, while you are right that Pedrick designed the Coast Guard 44 built by Morris, he also updated the McCurdy and Rhodes Navy 44, to a new, although derivative, design. You can verify this here.

  • George lewis Sep 30, 2012, 10:05 am

    Hi John: there are many choices in selecting an offshore cruiser. Wide vs. narrow, heavy vs.light, deep draft vs shallow. All can work but choose one and you will you will need to follow a path. Choose a long narrow design and and you loose form stability. Then choose a deep draft to improve stability and the boat will heel befor the keel will start to work. To counter the deep draft design a lifting keel. Shallow bilge add compartments. Design the fin keel to take a grounding at full speed . Impact the interior with a keel well spanning from hull plate to to deck plate. Add 4 wt compartments and build in aluminun. Now you have a design outside the norm but an good offshore passage maker. George

    • John Sep 30, 2012, 10:42 am

      Hi George,

      Sounds like you have a great boat specified, but its not the Adventure 40. The cost of the four watertight bullheads and the lifting keel would blow our budget right out of the water.

      Keep in mind, we are not trying to duplicate the existing French boats here. Boreal already has that cracked. What we are aiming for here is a simpler less expensive, but just as strong, boat that can still cross oceans. To do that, we must concentrate on the basics to the exclusion of all else, so that we have money in the budget to build a quality boat.

      You are right that too narrow a beam will make a boat tender and too reliant on draft for righting moment. But it is very possible to design a boat that hits the sweet spot of sail carrying capacity without excessive draft or beam.

  • Antoni Campins Sep 30, 2012, 11:08 am

    Hi John,

    I fully agree with your specs. I am currently the owner of a swedish built fast U-shaped Comfortina 38 and I cruise in the Mediterranean, a place well known for the ever changing weather and square waves. I am happy with my boat in many respects, but not when I have to sail against the weather. In this case the boat is not comfortable enough and it pounds very often, making it difficult to have some rest. I am over sixty and I plan to sail further when my wife gets retirement, but I need a rest from time to time to be fully awake and ready, so I have signed up today for an Adventure 40.

    Thank you very much for your commitment to the website and for the useful comments in so many areas and for the remarkable photographs.

  • Bob Hinden Sep 30, 2012, 3:42 pm

    Interesting article.

    While I am a bit biased, I own a Valiant 42, it strikes me that the V42 has many of the qualities you are looking for. I, and I suspect your readers, would like to see some comparisons with what you are trying to achieve and compare with boats like the V42.

    I am not sure I am in the market for a new boat, but I am following this series with a lot of interest. You are building what I was looking for when I bought my V42.


    • John Oct 2, 2012, 8:08 am

      Hi Bob,

      Sorry, I some how dropped the ball on your excellent comment.

      I think you are absolutely right that the Valiant 40 and 42 are excellent boats that have many of the qualities we are looking for in the Adventure 40. The two people I know who have one of these boats, both very experienced, love them and have sailed then tens of thousands of offshore miles. In fact, if there were a lot of boats like the Valiant 40 around either new, or second hand in ready to go voyaging condition for $200,000, I would never have bothered with the Adventure 40 in the first place.

      As far as comparing the two boats, that would be a whole post in itself, and one that I’m really not qualified to write, since I have never sailed a Valiant. Having said that, I would hope that the Adventure 40 can, using new technology and design knowledge, improve on the Valiant, just as I would hope that she will be an advance on our own “Morgan’s Cloud”.

      One point I can compare between the two, is that the Valiant 42 at 24,500 lb is a much larger boat than the the Adventure 40 at around 18,000 lb. Given that, and that the Valiant 42 is now being built on a limited production basis would lead me to guess (and it is just that) that a new Valiant will cost around double the budget we are aiming for with the Adventure 40.

  • Paul Mills Oct 1, 2012, 5:59 am

    Hi all,

    I think the need for a kindly motion and lack of slamming is significant. As some of you know, I have an Ovni 395. Last week we crossed Biscay, and inevitably ended up with some windward sailing towards the end of the crossing. The waves were moderate and a bit confused, and, yes, the boat slammed quite often. So, we were 3 days into our crosing (having started in Tregier) and after a couple of hours simply chose to bear away enough – onto a close reach, to stop the slamming so the off watch could sleep; luckily – thanks to Navtext we also knew that a front was coming through that would change our direct course from close hauled to beam reach, and so we arrived 4 hours later than we had hoped, having had a cracking final sail.

    On a seperate note during this crossing I also finally lost the ability to ignore the constant motor noise of my Simrad autopilot, whish is mounted in a cockpit locker – which acts as a sound transmitting box for the noise – next job this morning is talking with Simrad about any heat dispersal issues if I soundproof the blighter!


    • John Oct 1, 2012, 8:25 am

      Hi Paul,

      A lot of good points in your comment. I had always wondered if, and how much, the flat bottom of the Ovni hull form would slam and you have answered the question. Don’t get me wrong, I still like the Ovni concept, but like all boats, there are tradeoffs.

      Also, you highlight the importance of having the knowledge, information and experience to think tactically, and how much difference that can make to the crew’s enjoyment of a cruise. I wrote about that here.

      Good luck on soundproofing the Simrad motor, and please tell us if you have success. A crew member on MC christened ours “The Copulating Cats”. Of course I’m going deaf and sleep in the salon at sea so NMP (not my problem).

    • RDE (Richard Elder) Oct 1, 2012, 12:37 pm

      Hi Paul,
      On a scale of 1-10, which would you say is more objectionable? The pounding characteristics of a flat bottom boat, or a pack of Simrad felines in heat? LOL

      • Paul Mills Oct 2, 2012, 6:35 am

        Hi Richard,

        Definately the cats. at 7-10. Am currently discussing ‘neutering’ processes with Simrad, and will report back in due course.


  • Enno Oct 1, 2012, 6:19 am

    Hi John
    There is one thing about the hull that concerns me. I’m not sure if this is still current. In an earlier post it was mentioned that the A40 is supposed to be constructed with a balsa cored hull and deck. I believe this is a very bad idea. I do not think I would ever buy a boat with a balsa cored hull under the waterline. I would probably not buy a boat with a balsa cored deck either. A wet balsa core is difficult to repair and it takes not more than a man with a drill to get it.
    I’d suggest solid laminate below the waterline and sandwich laminate using closed cell foam above.
    In another post it was mentioned that a glasfiberhull can be made as strong as an aluminium hull. At least below the waterline I think this is a great idea. Provided it can be done without too big tradeoffs in weight and price.

    • John Oct 1, 2012, 7:47 am

      Hi Enno,

      Thanks for your comment and concern, but we are getting a bit ahead of ourselves here. Richard (RDE) suggested resin infused balsa core (very different and much better than standard balsa in a by-hand layup), based on his years of boat building experience.

      However, no decision has been made on hull material, and nor will it be until a builder has come forward. At that point all the options for hull material will be considered in consultation with a good structural engineer(s). Rest assured that the strength and durability will be the overriding selection criteria.

      • Matt Marsh Oct 3, 2012, 10:34 am

        It’s impossible at the moment to do a complete structural design for the Adventure 40, for two reasons:
        1. Her hull and rig geometry isn’t known yet.
        2. A builder hasn’t been selected yet.

        When preparing stock plans, a designer can specify whatever construction method she deems appropriate. The choice of builders is then limited to those who can use that method correctly.

        The Adventure 40 will be a production boat. The builder will have input into the design- not to say “it’ll save me money if you make ___ thinner/weaker”, but so that he can tell the designers “doing it that way will take 300 hours longer the way our shop works, if we can integrate subassembly ___ and do ___ before starting ___ it’ll cost less and have a lower risk of flaws”. Without this kind of communication, the price point would be impossible to meet.

        That said, I believe that a vacuum-infused hull laminate (solid fibreglass below the waterline, balsa cored above, with solid fibreglass at all deck fitting hardpoints) will be the most economical way to meet our “beefy as hell” strength criterion.

        • John Oct 3, 2012, 11:20 am

          Hi Matt,

          Thanks, your arrival is always, for me, like that of a lovely fresh spring day—blows the cobwebs right out of my sometimes muddled mind.

          Engineers are cool.

          • paul mills Oct 3, 2012, 12:17 pm

            I agree with john, though me thinks I do not have his classical education….. always like no messing concise to the point posts

  • RDE (Richard Elder) Oct 1, 2012, 12:25 pm

    Hi John,
    In your previous discussion with Andre Langevin concerning the French “Dériveur integral” style of boat you rejected the concept as being inherently more expensive to build than a conventional keelboat with detached rudder like the proposed A-40 design. I am not convinced that is necessarily true for a production glass boat.

    Point #1—keel and bottom structure:
    A conventional lead keel requires a well engineered and fairly elaborate structural floor system to carry the load transferred from the keel bolts. The keel itself is expensive to build and will always remain the most vulnerable item in a grounding situation.

    In an integral centerboard design ballast is cheap and easy to install and adds to the bottom strength. If the hull is resin infused, thick layers of cheap matt and roving can be added to build up a 1/2-3/4″ thick bottom that will be the terror of any whale encountered with little added labor expense. It never can equal metal if grounded on a sharp rock, but it can be far tougher than a conventional keel boat design.

    The keel/centerboard will be near neutral buoyancy requiring little lifting force and no elaborate mechanism, and can be as large as a conventional keel if desired, with a more efficient draft and shape. It can be lightly built, even to the point of having a sacrificial lower section although that should not be necessary.

    So, at this point build cost comparison should be close to even.

    If one forgoes the fashionable twin rudders in favor of a vertical transom with a transom hung kick-up rudder and tiller steering, a retractable rudder system need not be more expensive than a conventional hull mounted spade rudder with its long stainless steel or carbon shaft, sealing gland, and dual low friction bearing system. It will certainly be easier to service in the water or while under way.

    Grounding Skeg:
    The secondary support point for beaching an integral design is the prop skeg. As such it must be massively strong and more expensive than a bolt-on prop strut—– not a bad thing should you run over a deadhead log in the middle of the night in Alaska.

    So, everything else being equal, a production “Dériveur integral” design should be no more expensive to build than the A-40. Of course things are never equal!

    1- Canted aft running boards as used by Boreal are so desirable that any designer would be remiss if he didn’t include them even with their added expense.
    2- The search for form stability to replace lost ballast stability invariably results in a beamier design, which in turn increases displacement and materials cost.
    3- A large interior centerboard trunk defines the interior design, pushes the galley to the center of the boat, and requires additional beam.
    4- A flat bottom invariably pounds under some windward conditions, although the motion characteristics created by having the center of balance near the center of occupancy produces a more comfortable motion.
    5- The integral boat needs to be sailed at lower angles of heel, which is inherently more comfortable than sailing on your ear.
    6- The integral boat is probably in fact safer than a conventional keelboat in wave conditions, with its center of effort moved aft and keel/centerboard retracted.

    So, any additional production cost will derive not from the cost of retractable appendages, but from the implications they have for the overall design. And of course, selling a sailboat that doesn’t have a keel to an American is as difficult as convincing him to buy a bare aluminum boat!

    • John Oct 1, 2012, 4:32 pm

      Hi Richard,

      Thanks for the comment. I’m sure your right, given your experience of building boats, that the boat you outline could be built at the same price as a fixed keel boat. Not only that, I think it might be a very cool boat.

      But, as you point out in your last sentence, such a boat would only appeal to a small audience and further, it is, at least to some extent, a duplication of what is already being done well in France.

      On the other hand, the Adventure 40, as I see it, needs to be a boat with wide appeal, if it is going to sell in the numbers required to make the concept work.

      Also, while I’m sure you are right that centerboards can be done simply and strong, they are not without issues at sea. And in addition, I believe that sailing a centerboard boat well offshore takes more experience and skill that doing the same with a keel boat. For example, leaving the board down in certain conditions can be down right dangerous because of the boat’s tendency to trip over the board and not slide sideways (skid) when hit. (I raced a lot of miles in a centerboard boat.)

      Since the whole idea of the Adventure 40 is to attract new people to offshore sailing, we want to make the boat as forgiving and easy to sail as possible.

  • Axel Oct 1, 2012, 2:21 pm

    As my experience is very limited compared to yours, John, I am unsure about what follows, and would like your comments. But it seems to me that you are treating all u-shaped hulls as having the same characteristics, whereas in my admittedly small experience there are great differences when it comes to pounding when sailing hard on the wind.

    My previous boat, a very flat-bottomed dufour 30 built in 2000 certainly pounded. My current Rob Humphrey- desgned Elan 333, with u-shaped sections all the way, will also slam when motoring into a seaway. But when sailing hard on the wind and heeling, the motion is completely different. Of course, there are conditions, with steep, short waves, when the boat motion becomes uncomfortable, as the boat stops a little for each wave (even if it is still not slamming). Having sailed the boat for instance from Senegal to the Azores, with 10 of 14 days hard on a true wind of average force 5 to 6, I can say very confidently that it does not pound much. This does not mean that I would say that the motion is sea-kindly, far from it. As a light and not very large boat it is ‘lively’, with often jerky movements. These, however, seem much more to be caused by waves throwing the fairly wide stern sections around, more than from the flat forward sections hitting the waves.

    Therefore the promise of a seakindly hull for the adventure 40 is certainly tempting to me. But not because I am particulaly bothered by pounding.


    • John Oct 1, 2012, 4:42 pm

      Hi Axel,

      Well, first off you are a lot tougher than me, or I suspect most people. Ten days beating to windward in a 33′ boat, yikes! After six days in my 56-foot boat that does not pound, I was whimpering. Seriously, I think your tolerance to pounding might be rather higher than our target market’s.

      Now as far as whether or not a U shaped hull can be designed that does not pound? Beats the hell out of me. I’m not trying to design a boat in this post, or at all—I’m not qualified. All I was trying to do with my analysis of my own boat’s shape was to show one way in which a sea-kindly boat can be shaped. Are there other ways? Probably. Are there better ways? I don’t know, but I’m sure that the Naval Architect that designs the boat will explore U shapes if it makes sense. Just as long as he or she remembers my chainsaw! 🙂

      • Axel Oct 1, 2012, 6:30 pm

        Thanks for a rapid reply, John. Now, don’t get me wrong, I’m not trying to argue against the kind of hull you suggest. I trust your experience and am sure that the ideas you sketch out should lead to an excellent hull, including a moderate deadrise or v-shape like on Morgan’s Cloud. So I am not at all suggesting that you should go for an u-shape. Nor was the point that I’m particularly tough, rather the opposite, that the ride was much smoother than most would expect (including my twenty-year old son and myself before we set off). Of course we sailed conservatively and with reduced sails, 0n the average doing just under five knots over the 14 days. Still, I think your take on the u-shape in general as inevitably leading to pounding and risking structural damage if you go against the wind on open ocean is exaggerated, and does not take into account that different u-shaped designs can have different sea characteristics. This, at least, is my conclusion from having owned two such boats, one a pounder and the other not pounding much.

        On the other hand, my boat before the two u-shaped had forward sections very much like Morgans Cloud, and for a 29-footer was an excellent sea-boat. It was a Danish design, by Arne Borghegn, called Naver 29. And as long as the Adventure 40 has sufficiently sail to move in light winds (which the Naver didn’t really have), I would be very happy with that hull shape again. And as perhaps you can guess, I value the ability to go to windward highly, just like you do 🙂

        Sorry I’m so longwinded,
        best Axel

  • Eric Bretscher Oct 2, 2012, 12:03 am

    Hello John,

    I am going to pick on a few points here as well because I think you are promoting misconceptions.

    You write “A boat that sails well upwind will almost certainly be easy to steer, comfortable and quite fast enough, for a cruising crew, downwind”. This is simply completely wrong. In fact, there are many designs that have all these upwind characteristics and are simply horrible downwind, rolling and wandering all over the place. Just think about some of the 1970s IOR and Admiral’s Cup boats. Many of them ended up cruising later and they were only ever any good upwind.
    There is little relation if any between upwind and downwind performance in my experience. In fact, one of the biggest challenges in a design is precisely getting a good balance of both.

    You keep picking on “flat bottomed boats”. At the risk of stating the obvious, these boats also heel upwind and they don’t sail on the “flat”. In fact, if the hull is well designed, they sail on the flat downwind where they benefit from it, and on the turn of the bilge upwind, which does wonders when it comes to preventing pounding.

    In 1995 I sailed a Dufour Arpege from the Azores to St Helena, 3000NM hard on the wind and tacking from the Equator, against SE Trades of 20-25knots. The Arpege has forward sections not unlike Morgan’s Cloud, quite deep and nicely V-shaped, but also a fin and bulb keel. The seas were quite short and steep and it pounded every mile of the way. The V-shape is completely useless and even harmful if the hull lands on the side of the V due to heel angle. Had I kept the boat more upright to get a better ride, it wouldn’t have developed the power needed to punch through.
    This being said, the Arpege was a pretty decent sea boat, it didn’t always pound upwind by far and no amount of wind or sea ever knocked it back.
    Morgan’s Cloud may be gentle, but – no disrespect – I can’t see it making any decent progress upwind with that keel in rough seas. Now, when you are not going too fast, not really pointing and making a lot of leeway, a nice easy motion with no pounding comes quite easily and hull shape doesn’t matter so much.

    You can’t assume that a given hull shape will behave the same in the sea on completely different designs with different displacements. Many parameters all influence stability, which influences heel angles, at which point you need to reconsider the shape of the heeled hull in relation with its intended purpose.

    If you are going to start constraining the hull shape, then you need to step up and design the boat. If you are not going to do that, then let the designer do it, because otherwise he might well try to please you – the client who pays his bill – and the outcome will be inferior.

    Best regards,


    • John Oct 2, 2012, 8:27 am

      Hi Eric,

      Thanks for your comment and your very good point that there are a lot of different ways to design a good offshore boat, and the same for a bad one. Also your point about heel angle, stability, sail carrying ability, and the relationship to a sea-kindly ride is absolutely right on the money—boat design is complicated.

      You and a couple of others have pointed out, quite rightly, that I’m biased against flat bottom boats. Well we all have our biases and that’s mine. But its not totally baseless. Last week I was playing around with design concepts with one of the most talented and experienced naval architects alive today and in that process he added 1000 lb of displacement to a Adventure 40 concept sketch just to increase and reshape the V in the hull form to make the boat more comfortable.

      Having said that, I think you may need to re-read my post, particularly the first three paragraphs, where I made clear (or at least I think I did) that I was going to talk about some boats that work well offshore and some that don’t. Nothing I wrote in the post was meant to imply that my own boat was perfect or that there were no other hull shapes that are just as good, or better. In fact I even highlighted “Morgan’s Cloud’s” fairly inefficient keel and suggested that we could now do better at the same draft. (Don’t forget that MC is no dog, we have won our class twice in the Bermuda race. When powered up, she goes up wind like a train, but does make quite a bit of lee-way.)

      I also specifically said that I was not going to constrain the hull shape, as long as the boat met the conditions I have laid out. I quote from the post:

      Over the last few months, since I dreamt up the Adventure 40, people have been asking me what the hull form will be. The answer is that I simply don’t know.

      After all, I’m not a naval architect and I certainly would not presume to tell the very talented people who are, and have expressed interest in the boat, their jobs.

      As to the 1970 IOR boats, I raced on a bunch of them, and most of them were terrible boats, both upwind and down. Yes, they could go up wind “fast” when measured against each other, but put against a boat of the same size not constrained by the IOR rule and they got creamed both ways. (Think about the J44.) Also, most of the IOR boats that I sailed on would pound your teeth out offshore.

      • Eric Bretscher Oct 3, 2012, 8:38 pm

        Hello John,

        No hard feelings! What I meant is that if you overly constrain or “channel” the design, the designer is limited to making your solution work, instead of drawing on his ability and experience to create one that might even exceed your requirements and expectations.

        What I see now developing here is in fact a completely different boat than what I had pictured a few days ago when I ran into the A40 thread and read through the various requirements in terms of outcome.

        Just looking out there shows that there is a market for every boat. Developing a design using input from a public forum is an unusual and potentially quite challenging exercise and – don’t get me wrong here – you are doing an impressive job managing it.

        Wishing you the very best with your project.


  • Viv and Mireille Oct 2, 2012, 9:46 am

    John, Eric et al: I think the point here is that the Adventure 40 is to enable fairly new sailors to the world of ocean sailing in relative comfort and safety. I say relatively because no matter what shape the hull is, the sea is a dynamic environment and poses challenges constantly. Being on a relatively easy motion boat goes a long way towards safety and mitigates lack of experience to a certain degree.

    The Adventure 40 is now more than a concept at this stage and I am sure that given the criteria that has been set out, an architect will come up with a good design fit for purpose. We all have our preferences and experiences, good and bad. Whether flat, round or ‘V’ there are certain inescapable design points that can dictate the upwind and downwind characteristics ‘to a point’. As I said earlier, the sea is not flat nor stationary and different areas of the hull can hit it at many different angles depending on conditions.

    John has already stated clearly that he is not an architect, nor am I , but I know that some boat behave better than others in certain sea conditions and I think that the collective experience of the forum is better suited to positive ideas and input rather than disagreement and challenge at this stage.



    • John Oct 2, 2012, 12:35 pm

      Hi Viv,

      Brilliantly said, much better than my attempt. Thanks.

    • paul mills Oct 3, 2012, 12:24 pm

      Hi viv,

      Couldn’t agree more.

      I am all for outcome driven conversations and looking forward to contributing in any way I can.

      John, keep driving us all towards decisions and quality outcomes within a sensible timeframe and wordcount…..


  • Dick Stevenson Oct 2, 2012, 2:13 pm

    Just a couple of FYIs that some people may not be aware of: The Valiant 42 (Alchemy is a 42) is the same hull as the Valiant 40 of well earned fame. In the mid 90s Valiant added a bowsprit/anchor platform, taller rig and some additional mostly cosmetic changes and, presto, out popped the Valiant 42. Valiant’s are also among of the few true cutters (mast close to amidships) about, and therefore comfortably able to use some of your helpful observations on staysails and jib topsails and their usefulness in offshore sailing that double headsail sloops could not. Alas, I believe that, for a couple of years now, Valiant’s are no longer made at all, although I would love to be contradicted. I also believe, at the end, that a fully tricked out V42 was probably going for more than 3 times the projected cost of an A40. Finally, about weight: one attribute of Valiant’s that most pleases me, is how well she sails. She has absorbed our full time live-aboard weight (full tanks, months of stores spare parts etc.) bringing her up to 32,500 lbs without appreciably undermining her excellent sailing characteristics.
    My best, Dick Stevenson, s/v Alchemy, Newtown River, Isle of Wight, England

    • John Oct 3, 2012, 7:55 am

      Hi Dick,

      Thanks for the excellent overview of an excellent boat.

      You make a very good point about the load carrying capability of this type of hull form—a very important attribute for a successful cruising boat.

  • Steve Guy Oct 2, 2012, 4:11 pm

    John et al,
    I own a Ted Brewer designed Morgan 382, a very good old production boat built to a price. It has similar forward sections and keel depth of Morgan’s Cloud. It has not pounded in a variety of upwind conditions and is quite dry. It will slam in a very short steep head sea under low power as found in gale winds and shallow waters of the Abacos, Bahamas, as most boats would. It requires some steering downwind even though it has a fairly long, shoal draft fin and a skeg hung , model 384 (larger) rudder (with aperture and three blade prop).

    There is an article by Ted Brewer on page seven of the June/July Good Old Boat magazine in which he states that extensive tank testing of the 382 hull with both Brewer’s NACA fin and one designed for the boat by Henry Scheel showed, “…that the chunky NACA fin
    was superior in every respect…” The 382’s ballast is inside the fiberglass fin (less expensive and can be made quite strong). I recommend you read the article.

    I am in almost complete agreement with your hull shape and performance parameters, having logged many ocean miles myself. Were I to have a new boat custom designed I would specify tiller steering, assuming the boat would be well balanced, probably with a vertical transom and kick-up outboard rudder unless the designer could persuade me otherwise.

    Wishing success with the A-40 project,

    …Steve Guy.

    • John Oct 3, 2012, 8:02 am

      Hi Steve,

      Thanks for the information on the Morgan 382.

      Brewer boats have taken a huge number of people a huge number of miles in safety and comfort.

      Interesting about the keel comparison. Note that I think that the Adventure 40 may, depending on testing, have a modernized Scheel type keel. The point being that a lot of designers (Chuck Paine for one) have taken the Scheel concept and improved it. In fact it can be argued that Scheel was the father of the modern bulb keel since he was, I believe, the first to optimize a keel for a lower center of gravity for a given draft and to take advantage of the end plate effect.

  • Steve Guy Oct 3, 2012, 3:32 pm

    Ooops. The referenced article is in the June/July 2000 Good Old Boat.


  • Gene Gruender Oct 6, 2012, 9:58 pm

    I’m sitting here on my Cheoy Lee 40 Midshipman reading the details of this project. We’ve cruised on a previous boat, and done a few passages on this one. It’s occurred to me that this Adventure 40 might be of interest, rather than continuing with this often times project we now sail.

    I’m not well versed in hull shapes, but I do have a lot of thoughts about the innards, like tankage, layout and some other items like that. On a previous boat I added a lot of fuel tankage, as we found there is more motoring than cruisers like to admit. Upon selling her, I found the new owner ripped some of it out, saying he wasn’t going to be motoring, he was sailing. I also notice it hasn’t left the slip in 4 years.

    Which brings me to my question. Are you developing a list of preferences of things of that sort? What tankage should this boat have, both fuel and water? Layout considerations? For most, there is a wife or partner involved and I can assure you, mine won’t know beans about the things discussed so far, but she’ll have some pretty strong opinions about layout and creature comforts.

    It would seem silly to spend a couple years deciding on hull shape, then serially start trying to find the rest of this out.

    For me, for example, I would want 2 main fuel tanks, (100 gallons total) and a day tank. Not necessarily built into the boat, but at least have a reasonable place I could add those without going in and cutting and starting over. Which I’ve done twice. After all, as I understand it, this is a cruising boat, not only a passage maker. Cruisers are going to want to go, wind or not. Twice, going from Isla Mujeres, Mexico to Port Aransas, Texas in June, returning from the Caribbean, we had no wind for almost the entire trip. We burned all the fuel we had both times, at that time about 70 gallons.

    We would like to have 2 water tanks, which is probably pretty standard, in case one gets contaminated.

    We would like at least one place in the cockpit where the off watch person could stretch out and sleep.

    You get the idea. I’ve reached the point where I realize I could just buy an Adventure 40 if it was available and practical. I have a continual list of things that need to be done to this Cheoy Lee, and I’m getting to the age where projects aren’t so much fun.

    I also know that I don’t have the knowledge to select a random boat that will sail well, and another used boat could just be another project and still not sail well. At least the inputs of this group should insure it’ll sail better than something the salesmen design.

    • John Oct 7, 2012, 7:46 am

      Hi Gene,

      Great comment, thank you.

      First off, don’t worry we are not going to spend a couple of years messing around with hull forms. If for no other reason than the fact that I could not stand it!

      A very good point about the need for a cruising boat to have good range under power. Don’t worry, the Adventure 40 will, although she will achieve that by having a really efficient engine installation and slippery hull form, rather than big tanks.

      On the layout and gear. That will be coming soon. But there is one huge point here: Your Midshipman 40 at 27,000 pounds is at least half as big again as the Adventure 40, at 18,000 pounds, and probably more than that, since I bet your boat actually weighs well over 30,000. Therefore you and your wife would have to down-size your expectations a long way to fit into an Adventure 40. I’m guessing that to be happy, you would need an Adventure 50.

      On the other hand, you might decide that the simplicity and reliability, at the sub 200k price, of the Adventure 40 was worth the sacrifice in space. Only you can decide.

  • Eric Schlesinger Oct 8, 2012, 1:46 pm

    Dear John,
    We like the discussion.
    Before buying our Gillmer ketch we read C A Marchaj. Although I cannot claim to have understood the math, we got the point. Wondering why he is not mentioned in the above discussion. Is he too old fashioned, out of date, or proved wrong?
    Thanks, Eric and Sue

  • Larsen in Norway Nov 13, 2012, 4:41 pm

    Hey.I follow your web site with great interresse and especially your project with the A40.
    I have only one question. Will the A40 be CE rated and approved in Europe.

    Thanks for an otherwise very interesting and informative Web site


    • John Nov 13, 2012, 7:34 pm

      Hi Larsen,

      The final decision on that would be the builder’s. But I would certainly expect the boat to be CE rated. Of course it might be built in Europe, it all depends on who steps forward to build it.

  • Logan Greenlee Dec 31, 2013, 12:11 am

    An old thread I know… but as a small addendum to your belief that Rhode’s designs are seaworthy and fast – Philip Rhodes designed the Rhodes 41′ in the late 50’s. Hull number 25, “Restless” sailed by Eric Crawford won the Lighthouse Trophy in the Newport to Bermuda race in 2000.

    • John Dec 31, 2013, 2:01 am

      Hi Logan,

      Fast ran in the family. The Rhodes of McCurdy and Rhodes was Philip “Brodie” Rhodes. Both he and Jim McCurdy worked for the Philip Rhodes you refer to before setting up M&R in 1965. You can read more here.

  • George M Apr 23, 2014, 3:11 pm

    Hi all and John,

    I cannot overstate how right John is here. I have significant sailing experience on the following makes of yachts,

    Westerly Griffon (26ft heavy boxy bilge keeler)
    Westerly Seahawk (34ft heavy, beamy, center cockpit, bilge keeler)
    Jeanneau 43DS (43 ft light-moderate, beamy deck-saloon, fin with bulb)
    Jeanneau 56DS (56 ft light-moderate, beamy deck-saloon, fin with bulb)
    International folkboat (26ft slim, low windage longkeeler, balanced hull lines. Relatively light weight)
    Hanse 370 (37ft very beamy, light, fin with bulb, present boat).

    Of these the best boat close to the wind in a blow was the folkboat. It could get wet in chop, but the boat would beat upto 45 degrees off the wind into a force 6 with a single reef in the main at 4-5 knts. You could let go of the tiller and she would plod along like that for 30secs without rounding up. N0t bad for a boat of less than 5000lb’s displacement and only 26ft in length.

    The worst is probably my present boat, the Hanse 370. Last summer we got caught sailing down Loch Fyne in Scotland in a force 6-7 up the loch and I could not get the boat to sail down the loch for love or money. And the pounding!!! Eventually I had to give up and motor sail her into Loch Tarbert. That was a miserable experience. The Jeanneau’s aren’t much better.

    Indeed all three are a good advert for why the modern craze for wide beam and transoms together with light weight and an over reliance on form stability is so misplaced. In quartering seas they are all 3 difficult to keep on course with horrible corkscrewing motions as the waves pass under the transoms. My wife actually got a repetitive strain injury on the 56ds keeping her on course in a force 7 in a quartering sea for 40 mins and couldn’t use her arm for 3 days after! They all have to be sailed flat in order to avoid excessive weather helm and rounding up so you need to reef early, but they are so light that if you reef too much they are stopped dead by any kind of sea (the Hanse is worst for this). So you are faced with the choice of powering up and dealing with the poor handling or powering down and baring away. Resorting to twin rudders to fix this problem, does nothing to fix the issue with quartering seas, adds to the complexity of the yacht and deadens the feel at the helm as well as leaves the rudders in exposed positions. Basically, a properly designed cruiser should not need twin rudders.

    The additional weight of the Westerly’s, and the more balanced hull shape meant that they coped better with their large beams despite being handicapped by bilge keels. In light winds they sailed poorly, and they had bad leeway into a blow, but they at least could plough into a sea with relative comfort. Moreover, they didn’t need to be sailed flat in order to keep their rudder in the water so one could keep the power on to maintain way. They also had less problems in quartering seas for the same reason.

    Hence in my experience,
    A boat with unbalanced lines (wide transom, pinched bow) is miserable to keep on course both downwind and upwind.
    Slender boats go to windward better than beamy ones.
    Fat (but balanced) boats are to be preferred downwind
    Heavy boats are preferable in heavy airs, while light boats are preferable in light airs.
    Veed bows significantly improve crew comfort

    All in all, if you want to be able to sail in light and heavy airs both upwind and down then the ideal hull form for a given displacement is one that has a long waterline with reserve bouyancy forward, moderate-slender beam for its length, balanced lines, moderately veed sections forward, and lowish freeboard. This is exactly John’s specifications for the A 40 and I commend him whole heartedly for it.

    For a long distance cruiser, hull form should definitely take precedence over accommodation both on deck and below it. For safety reasons, a long distance cruiser has to be able to sail out of trouble, and for comfort and safety reasons it has to kind in its motion. Finally, a long distance cruiser must be able to self-steer under wind vane to look after its crew. All of these are determined by hull shape and any of them is more important than a palatial aft cabin and ballroom saloon, etc.

    The modern light, wide, unbalanced hull shapes with no v forward are suitable only for coastal cruisers who will only sail to windward in less than a force 5 and downwind in less than a force 7. No boat designed like this should be able to get an RCD A classification or the american equivalent. That they regularly do tells you all you need to know about RCD ratings.

    George M

    • John Apr 23, 2014, 4:32 pm

      Hi George,

      Works for me! Wait until you see the A40 lines in a few weeks. You will be a happy camper.

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