Adventure 40 Dimensions and Hull


We are now ready to reveal and discuss the specification for the Adventure 40 prepared by Maxime and Pascal, the partners in France who are going to make the Adventure 40 real, and who are being advised by Vincent, the naval architect they chose for the project.

It’s been nine years since we thrashed out the Adventure 40 mission and core design concepts, so rather than just pasting in their specification I’m going to share each part and then relate it back to that earlier shared and deeply-discussed work, so we are all looking at this in the same context.

This approach will also help those of you who were not in on the idea in the beginning and are trying to figure out if the Adventure 40 is the boat for you.

This is important to get done now because the boat is targeted at a specific owner profile rather than trying to be a boat for all—an unattainable, but all too common, goal in boat design.

Or, to put it another way, part of my goal over the next few Adventure 40 articles is to provide enough information for some of you to decide that the boat is not for you—no shame in that, and better we all know what the real market is sooner rather than later.

This will then give the French team a clearer idea of how many people are committed to the boat, or at least deeply interested.

Let’s start with the dimension envelope that Vincent will design the boat to fit in:

  • Light ship displacement: 7 to 8 metric tons (15,400 to 17,600 lbs)
  • Load carrying capability: 2 to 3 metric tons (4400 to 6600 lbs)
  • Length overall: 11.8 to 13 meters (38.71 to 42.65 feet)
  • Draft: less than or equal to 2 meters (6.5 ft)

To put these numbers in context, the Adventure 40 is:

If that does not make sense, please take a moment to read this article.

Two-Person Boat

Or, to put it another way, the Adventure 40 is a couple’s live-aboard cruising boat.

If you are looking for a boat to take a larger family longterm live-aboard cruising, this is not the boat, at least unless you have a high tolerance for crowding. There won’t be room for more than one decent sleeping cabin, once Vincent draws in proper storage and machinery spaces, and not enough load carrying capacity.

One day I hope we will do an Adventure 48 to 52, displacing around 11.5 metric tons (~25,000 lbs), which would be a live-aboard boat for a family of four, for example.


The 2-meter (6.5-foot) draft was chosen based on Phyllis and my experience of cruising with just that draft for some 30 years, while finding it the optimal tradeoff between performance and access to ports and anchorages.

Also, the Adventure 40 will not have lifting appendages. More on why not here.

A Great Sailer

The good news is that, by using modern design and not being constrained by the all too common, but deeply ill advised, goal of building the biggest boat for a given length, the Adventure 40 will be way faster and more comfortable when underway than the Westsail 32, and a better sailer than either. Sorry, Valiant 40 and Westsail 32 owners, I know they are great boats, but design and build have come a long way in 50 years.

Room for a Great Interior Layout

Also, contrary to common opinion, Vincent can design a way more functional layout in a longer boat for the same displacement than a short fat one. Here’s why.

At a Great Price

More good news: the relatively small size of the Adventure 40, along with keeping her standard (no options) and simple, is a lot of why I’m confident that the boat can be sold ready to go for the target price of about US$250,000 and still be of far higher quality than even boats costing far more.

Hull Shape

That’s just the numbers, now let’s look at the sailing capabilities that make the Adventure 40 different from any production boat available today—the primary reason we are doing this:

  • Sufficiently narrow and V-shaped forward sections to prevent pounding.
  • But still with proper volume and flare in the ends of the boat to provide reserve buoyancy to reduce pitching and keep the deck relatively dry.
  • Low moment of pitching inertia by keeping the heavy items (tanks, engine, chain) as close to the middle of the boat as possible, and by avoiding, wherever possible, weight in the bow and stern.
    • Most modern production boats suck in this regard, due to the trend of pushing the accommodation right out to the ends of the boat and then cramming them full of heavy gear.
  • Carefully shaped and matched bow and stern shapes so that the boat remains easily steered when heeled—no huge wide stern that will cause the boat to become hard to steer in a puff and drive the bow down into the next wave.

Bottom line, the Adventure 40 will be a fast, efficient sailboat designed to treat her crew kindly when the going gets tough, whether that be on a long coastal daysail against a rising sea breeze or a gnarly fall voyage to Bermuda.

Why does this matter more than the huge interiors we all see on boats designed to sell, not sail? More on that in a moment, but first let’s look at how the hull will be built.

Hull Construction

I’m excited to reveal that the French team have committed to building the hull from epoxy resin, not polyester as used in most production boats. The advantages are many:

  • Better resistance to water intrusion.
  • Blistering is non-existent on an epoxy boat.
    • Epoxy resin is used to seal boats built from polyester.
  • Much better adhesion to the fibreglass cloth and core.
  • Better impact resistance.
  • Better resale value.

All that’s great. But by far the best reason for building a boat out of epoxy resin is that there will be no secondary bonding problems, that common curse of production fibreglass boats where the joints between assemblies like bulkheads, chainplate knees and, worst of all, keel reinforcing members, come away from the hull over time because of the inability of polyester resin to stick to itself once it’s dry.

Sure, builders will claim that they got all the members in and glassed while the hull was still tacky but, in fact, that often does not happen—ever heard of weekends…or happy hour at 5 pm?

You can read more about secondary bonding problems over at Steve D’Antonio’s site.

Bottom line, they suck, as I know all too well after having to rebuild my Fastnet 45 forty years ago, and getting a second dose of secondary-bonding headaches now:

The deck, bulkheads and hull will all be cored with, of course, the core removed in the way of fittings and through hulls.

…I’m pausing for all the wailing and gnashing of teeth to die down…

And, yes, I had to think about this some, too, particularly since we originally specified that the hull be solid glass, but there are a bunch of benefits to going with a cored hull, most notably:

  • Much higher strength- and stiffness-to-weight ratio.
  • More volume for a given displacement.
  • Better payload than a heavier boat.
    • Weight we don’t put into the hull we can put inside the hull.
  • Less pitching due to less weight in the ends.
  • Able to withstand a tighter headstay without bending or damage.
    • Makes a huge difference to windward ability.
  • Much lower chance of deck leaks due to less flexing of the entire structure.
    • It’s pretty much impossible to build a solid fibreglass hull that does not flex at sea, at least without turning the boat into a slug.
  • A higher ballast-to-displacement ratio. Weight we don’t put in the hull can go in the keel.
    • More sail carrying power.
    • Less heeling.
    • More easily driven.
  • Better longevity over time: flexing begets more flexing, and on it goes.

Bottom line, stiffer lighter boats sail better than heavier boats, and can even have as good or better motion if the hull form is right.

And we can already see these advantages being applied by the French team in reducing the target displacement for the boat from the original 8 to 9 (18,000 to 20,000) to 7 to 8 metric tons (15,400 to 17,600 lbs) displacement.

Of course, the big worry with core in the hull is water intrusion, but the use of epoxy and their plan to vacuum infuse will reduce that risk to a fraction of that of polyester boats with balsa cores, the method of construction that has generaly given cored boats a bad name.

Talking of which, although we have had to fix a few areas of wet balsa core on our J/109, we have found no large areas, despite some truly stupid fitting installation mistakes (both by the builder and after market) that had been letting water into the core for years. This seems to confirm that vacuum infusion limits problems.

Bottom line, I think a hull cored with epoxy is a good call. That said, I will be even happier if they use some sort of closed-cell core material that will further limit water migration issues.

Let’s Go To Bermuda On an Adventure 40

OK, now we have a modern, but moderate and wholesomely-designed hull built out of durable but light and stiff materials.

Cool, but what does that really mean when we get out there cruising on an Adventure 40?

To understand that, come along with me on a voyage to Bermuda. Why Bermuda? If your boat won’t get you to Bermuda, south across the Bay of Biscay, or across the Tasman to New Zealand, quickly, safely and comfortably, it’s not a boat you want to go voyaging in.

Yes, the following is a fantasy, but one based on my over 25 (lost count) transits of one of the tougher pieces of ocean on the frequently-traversed cruising routes.

Let’s say we are three-and-a-half days out of Newport. We left in company with some friends on a typical modern wide boat with a very wide stern.

So far, it has been a reach with the wind in the northwest to north, where it has been since the cold front came through the night before we left, so our large-tushed friend has stuck with us—just about any boat will sail halfway decently on a broad reach.

But now clouds are building and the wind has been veering all day and finally settles into the southeast, blowing 20-knots true, gusting higher, and quickly building a nasty sea, as the east-bound low-pressure area to our north drags a warm front over us.

Bermuda is now dead to windward and still 150 miles away. We strap the boat down, trim the vane gear, and shelter under the hard dodger, as Vincent’s hull form starts to show that this is exactly the conditions he was thinking about when he drew her and engineered her stiff and strong hull.

A few hours after the wind shift, our friends drop below the horizon behind us. Their boat is staggering and rounding up in every gust and being stopped dead and knocked off the wind by every wave.

They are barely making 2-knots good toward Bermuda as we romp on, pointing high, with a velocity made good (VMG) of better than double that, toward the St. Georges Dinghy Club bar.

We chat on the VHF and they tell us that their lightly-built boat is flexing badly and so every hatch and port is leaking, turning the interior into a sodden mess.

And, to further add to their misery, the erratic steering behaviour of the boat is making it impossible to use their vane gear or autopilot, so they are hand steering and getting soaked by every wave while doing it.

A little more than a day later, aided by a bit of tactical cunning playing the veer to the southwest as the cold front comes in, we beat through Town Cut just for the fun of it and tie up to the Bermuda Customs dock, four-and-a-half days out of Newport, and with a powerful thirst that only a Dark ‘n’ Stormy will satisfy.

Four days later our friends are towed in looking battered and bedraggled. Apparently, the slamming and flexing got so bad that they were forced to heave-to for a day, which let a secondary low that formed on the front catch them with its associated gale-force winds.

That resulted in two more days heaved-to before the wind finally veered into the northwest and let them make Bermuda. At least the wind didn’t die completely, as it often does after frontal passage, because the water that was getting into their boat sloshed out of the shallow bilges and flooded all the electrics, taking out the engine.

Just a day dream? Hang out at the Customs dock in Bermuda and you will see many realities that look just like the experience of our imaginary friends.

Not Just For Going To Bermuda

So is the Adventure 40 just an offshore boat? No, her capabilities, while perhaps not as vital for coastal cruising, will still make getting there way more fun.

For example, the Bras d’Or Lakes, here in our home province of Nova Scotia, is one of the most wonderful and unspoilt cruising grounds in the world, but it’s also, more times than not, an over 100-mile stone beat against the prevailing southwest winds, which often pick up in the afternoons to the mid-twenties, to get back to our home waters in Mahone Bay, and three times that distance to get back to Maine.

And year after year, when going back west, we have seen most other cruisers staggering toward home, motor sailing while pitching horribly or, worse still, trying to drive their overloaded marina queens directly into the wind under power alone—a futile business once the waves get over one meter.

An Adventure 40 will change that chore into a fun series of boisterous but satisfying day sails between the lovely harbours of the Nova Scotia Atlantic coast. There is nothing, but nothing, like settling in for cocktail hour bathed in the smug satisfaction that a smoothy-executed sail against tough conditions confers…and watching other boats straggle in hours later is kinda fun, too…wait, who wrote that?

And then, after a couple of days, when the wind finally goes around to the northwest as the next high comes in, blowing a gusty 18 to 30 knots—northwest winds are almost always gusty on this shore—the easily-driven hull form and directional stability of the Adventure 40 will let us sail a fast and fun broad reach with the vane gear doing the work, while other cruisers spend a day struggling with the helm, as the changes in heel angle with every gust mess with their boat’s asymmetric hull form.

Trade Winds?

And what about trade wind passages off the wind, the ones we all dream of? Surely a wide-sterned boat will be better? After all, race boats are designed that way.

Nope, that only works with a boat that planes, which is not something that happens on a heavily-loaded cruising boat.


As I’m sure you have figured out by now, I’m excited about the way this is going. The French team are closely sticking to the base concepts of the Adventure 40, but bringing their own experience, modern developments, and innovation to the table.

Coming Next

Next, we have a fascinating paper from the team on the rudder, complete with an innovative idea for backup steering, and then we are on to the keel and how it will be made as resistant as possible to grounding damage, including another innovative solution.

And, somewhere in all of that, the French team want to get your views on the best way to finance the design process, so we will publish an article for discussion on the options they are considering.


So what do you think? Is an Adventure 40 the boat for you? Please leave a comment.

And if she is:

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