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.)

Before we can design a boat, we have to clearly define what the goals are:

#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.

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. 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.

#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.

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.

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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 18 years, as co-editor/publisher of AAC.

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