Question 1: Ted, what are your thoughts on boats like the Maine Cat 41, or the Shuttleworth Tek 35? Do these open cabin boats represent a viable alternative to an enclosed cabin?

Questions 2: Here is a concept I was playing with – instead of making the cabin like a lounge room and then needing to cover the cockpit to make a casual space, why not leave the cockpit open (like any other yacht) and open the cabin up more like a covered extension of the cockpit? A design meant for sailing and after sailing laid back ‘existence’ rather than for brochures and cocktail parties at the dock?

Response: I think the example boats in the first question are perhaps aimed a different market than one dedicated to comfortable ocean crossings and extended stays in exotic ports.

I get the sense that the Main Cat is perhaps set up for vacation stays in moderate waters, hence the commitment to an enlarged cockpit that displaces any option for any permanently enclosed communal living space. Canvaswork enclosures are lightweight and versatile. They are always a relative pain to maintain and set up however and ultimately they aren’t very strong, especially in large expanses. With the greenhouse effects engendered by this much ‘window’ you will probably be working the enclosure zippers as much as the sails in variable weather. Tents on boats are always difficult to appreciate aesthetically, from either side, but the example above could be worse I suppose; lots of windage with this one.

The Tek 35 is perhaps more of a mystery. Designs driven by `cool` with token, or even no concession to practicality may be fun up to point but they are unlikely to be appreciated for habitability. This one looks like it would be just as exciting to get aboard, and then get around on as it would be to sail.

If you don`t mind baking in the sun and soaking in the rain without respite and are agile enough to scramble around on curvaceous sloping surfaces, the absence of any communal shelter may not matter much.  Owners who pridefully endure the discomforts of racing dinghies may like this kind of thing and forgive a lot if it sails fast enough. Everything being reportedly ‘high tech’ may be a compensating point of pride in some circles.

At 35′, sailing catamarans are pretty tough to configure for cruising without compromises, at least this one concedes that point with some humour. (And there is no tent to interfere with the visual impression of speed at the dock).

What constitutes ‘a viable alternative’ really depends on what your intended use of the boat may be. As a responder to the want lists of ocean cruising aspirants and doers alike, and an adherent to the ISO design standards for offshore boats (in spirit anyway), I would say that neither of these configurations could be endorsed as ideal for that purpose. Provisions for many long term cruising amenities are noticeably absent. In spite of the all the marketing photos you see, the weather isn’t always nice

The Lecture

You may get the impression from marketing extravagance that boat design is purely an exercise in styling options for various living spaces, but there is a practical foundation issue with seagoing vessels; what portion of the available accommodation volumes will be maintained as weathertight?

Placing a barrier of high integrity between the zones that can be subject to wave wash in extreme circumstances and those that must ultimately remain dry for floatation will control the development of accommodation spaces.

The correspondence above is really concerned with that fundamental parameter; making the distinction between what constitutes the inside and what constitutes the outside the vessel?

.The simplest catamaran approach is to join two self-contained near-cylinders together with a platform; the distinction between inside and outside is readily apparent.

In the case of the excursion cat above, there is no doubt when you are ‘going below’ to use the facilities or service the engines, you are descending into something resembling a sewer; the semi-watertight manhole/door/hatch giving onto the deck delivers you to a steep stair ladder, and down you go. This is alright for a temporary endurance/adventure boasting point; and for a utility craft, who cares? But, for a catamaran yacht of a certain size, with some pretense of providing comforting and enjoyable shelter space, you will care.

Consequent to the absence of a deckhouse, the Main Cat 41 and Tek35 have to confine their access to hull spaces to two companion way style doors as does the excursion cat above. They may do it more elegantly but you are definitely descending into a relatively confined space.

To meet the ISO regulations for offshore use, companion door sill heights have to be much higher than they appear to be in the photo above (MC41) and any potentially floodable large cockpit volume has to have some very capacious drainage arrangements. I imagine however that this example is unlikely to be intentionally committed to really arduous passages.

When the addition of a deckhouse with bulkhead door is adopted, the bridge deck space becomes part of the interior rather than the exterior. It is the solid construction that delineates the distinction and permits closure-free access to the two hulls. In effect, the accommodations on the bridge deck may be contiguous with the ‘dry’ zones in the hulls once a cat has become big enough.

Though many cruising cat interior layouts seem to retain the vestigial sensibilities of ‘two pontoons and a platform’, a solid deckhouse actually permits the living spaces of the hulls to be in direct communication with the bridge deck communal space if so desired. The sense of ‘going below’ may be largely mitigated by opening things up, thereby making the hull accommodations more inviting and versatile.

Along with other ergonomic goals, this open concept may be tough to achieve in a small vessel, but it has been done for such boats as the PDQ36 (above) and the PDQ32. (Both of these boats however would have relatively confined cockpit arrangements compared to the MainCat 41).

Perhaps not readily apparent in the MainCat41 and Tek35 approach is the necessity of placing any galley facilities in a decidedly disconnected unsociable zone down in the hulls.  Keeping the cook in communication with the rest of the goings on and providing the sense of atmosphere (fresh) has to be on the want list for any serious cruising boat. The possibility of doing so is a uniquely catamaran advantage that I wouldn’t casually set aside.  Watch video for a living demonstration:

The option of going saloon-less becomes a non-starter with larger cruising cats which may provide both the indoor shelter and outdoor exposure experiences readily enough without much compromise to either. If you are compelled to stay within a smaller boat size range, have a thought to the boat design as whole and relate it to your particular needs.  If your boating experience has led you to prefer the assault of the sea breezes at the expense of shelter, you could opt for an open or semi-open arrangement on the bridge deck. I would suggest however that benefits of a communal closed cabin space with its potential for warmth, relative freedom from salt and moisture accumulation, privacy, air conditioning (blasphemy), place to display the grandkid pics, etc. should not be set aside lightly.

Few specialty design features may be provided without compromising some other aspect of a boat, usually something boring and utilitarian that you discover later may have been worth retaining.