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My goal in this first design review for boatbuilding.com is to introduce myself to you so that you can tell where I am coming from in the field of yacht design. My offshore sailing experience and my professional career have shaped a lot of my outlook on boat design and construction.

I am a strong advocate for free-standing rigs, and I like to question everything designers do in boat design because there is a lot of stuff that is just the same old, same old. "That's the way we've always done it" can be good sometimes, but a lot of times it is bad. While it is often good to rely on past experience, it sometimes makes us too conservative and too afraid to try something new. I am a firm believer that everything regarding boat design has both an engineering and practical basis for being there. I believe in the K.I.S.S. principle (Keep It Simple, Stupid). I also believe that form follows function, to a degree, but one must be careful not to draw ugly boats. Ugly boats (and here I refer to the beauty of line, proportion and shape, not fit and finish) cost the same to build as pretty boats, but a pretty boat is always easier to sell than an ugly boat.

The Globetrotter 42 is my own latest creation, but it has not yet been built. I do not have a client for it; I am the client. This is what I want for my next boat. There is not even a lines plan, but the design has a number of features of interest.

When Arliss and I were sailing Duprass, our Bianca 27, we discovered we sorely missed having a pilot house, such as we had seen on other cruising boats. It keeps cool and inclement weather off your back, expecially during night watches, as well as the hot sun out of your eyes and off your head during the day. You need inside steering in addition to normal outside steering. I also discovered from my years associated with Freedom Yachts that there really is no simpler, safer, more versatile rig than the free-standing cat-ketch. The Globetrotter 42's masts, in fact, are free-standing carbon fiber rotating wingmasts.

Loa:                    42' 0"
Lwl:                    38' 4"
B:                      13' 6"
D:                       6' 0"
Displ:                  22,000 lbs.
Sail Area:              1,269 sq.ft. (including masts)
Displ/(.01Lwl)3         174.4
SA/Vol2/3                25.86

• Aft cabin with aft T-cockpit
• Pilot house with inside helm, large chart table, and full-length berth
• Crash forefoot and scoop stern
• External lead ballast with bulb
• Cat-ketch rig with free-standing carbon fiber rotating wingmasts
• Twin carbon fiber rudders, stockless, retractable
• 50 hp diesel with saildrive in well-protected, dry space below pilot house sole
• Large, well-equipped U-shaped galley
• Large head with separate shower and wet locker
• Main saloon with fireplace and entertainment center, sea berths high and outboard of settee berths
• Forward cabin with upper/lower twin berths and seat (v-berths optional)
• Construction possible in composite, aluminum, steel, or wood-epoxy

I won't give you the blow-by-blow of the arrangement plan; you can figure that out for yourself by looking at the pictures. My inspiration comes from William Garden's Fast Passage 39 which I think is one of the best sailing yacht designs ever for offshore voyaging. The Globetrotter 42 has two sleeping cabins with one head/shower, a main saloon, pilot house, and aft cockpit with scoop stern. The keel is a short fin with beavertail bulb, the rudders are twin retractable stockless types, and auxiliary propulsion is by diesel through an offset saildrive. Construction would be in foam cored or balsa cored fiberglass.

The most notable features of this design are the rig, the rudders, and the pilot house/aft cabin arrangement. First the rig. The big disadvantages with a conventional stayed rig are:

The headstay and backstay define and confine the shape of the sailplan to a triangle. A triangle is the absolute worst possible shape you can conceive of to be a lifting foil. Why? Because in order to be its most efficient (high lift with low drag) the top of a triangular sail necessarily must twist to windward. This is impossible to achieve, and so you are forced to accept much higher induced drag (drag that is always created with lift) which creates high side force pushing the boat sideways instead of drive force pushing the boat forward.

The rigging is expensive to maintain and provides no lift. It produces only parasitic drag (drag with no corresponding lift).

Every part in the rigging is a potential failure point. Lose one small part through breakage, corrosion, or it just falling out of place, and the rig is almost guaranteed to go over the side.

A stayed rig is naturally unstable downwind. Because the boom cannot go farther forward than the after lower shrouds, a boat running downwind naturally wants to round up into the wind. In a heavy seaway, this can cause an uncontrolled gybe and/or broach.

A stayed rig is naturally unstable downwind

A cat-ketch rig totally eliminates these four big disadvantages. Without headstay and backstay, the fore and mizzen sails can be any shape--elliptical, square-topped, anything, whatever is most efficient---without the worry and wear and tear of chafe. Without the rigging, there is no parasitic drag. Without the rigging, there is nothing to fail. If it ain't there, it can't break. And finally, a cat-ketch rig can be set downwind with the booms forward of the beam wing and wing with the masts turned into the wind facing aft. Sail shape is superior, creating generous lift forces which are much more powerful than the squashed-against-the-spreaders shape of the main on a conventionally stayed rig which creates only drag downwind and is much less powerful. There are no wires resticting the positions of the booms.

but this rig can't gybe uncontrollably

The cat-ketch can't gybe uncontrollably. If it tries to, the forward sail naturally pulls the bow of the boat back downwind. To come about, you simply pull both booms back to an aft position and tack in the normal way. You can gybe the boat if you want to; gradually pull the booms around and let them fly to the other side where they gently come to a stop as they spill the wind. The gybe is gentle, not shocking. You don't have to worry about the boom breaking across the leeward shrouds--they are not there!

For a boat of about this length (in the realm of 40'), a free-standing cat-ketch rig becomes more economical to build than a stayed rig. I would expect each mast to cost $15,000 to $20,000, so $30,000 to $40,000 total. As a percentage of the total boat cost, expected to be about $400,000 (plus or minus, depending on the degree of outfit), this is roughly 10%, about average.

The weight of the masts would be about 200 lbs. each, which works out to about $100/lb. for each mast. Construction of the masts can be done by a professional mast builder, or if some intrepid soul wants to build them himself or herself, that is certainly possible. Back in the early 1980s, I developed a method of construction for free-standing masts in which a wood-epoxy shape is built first, and over this is laid the carbon fiber laminate. I have had masts built by this method in the US, Canada, and New Zealand. The method of construction is described in Professional Boatbuilder magazine, issue 14, Dec/Jan 1992, featuring the design of the wood-epoxy/carbon fiber wingmast on my Delft 25 design.

The center of gravity of a cat-ketch rig is generally a little lower than that of a stayed rig because most of the strength (diameter and wall thickness) is built in down low where it is needed the most, and then the mast diameter and wall thickness both taper uniformly to the masthead. Mast center of gravity is roughly 35-40% of mast height. In a stayed rig, the mast is almost always a constant cross-section and wall thickness throughout its height (except for any taper at the top end), which means that the center of gravity will be about 45-50% of mast height. The same applies to rigging--heavy stainless steel of constant section and weight. Its total weight, like the mast, is centered near the mid-height in the rig. As a result, the stability of a boat with a cat-ketch rig is improved over an identical boat with a stayed rig.

Another neat benefit of the free-standing cat-ketch rig is that the masts can be sealed nearly completely, adding a tremendous amount of buoyancy to the boat in case of a knockdown. Whereas a conventionally rigged boat with its heavy metal mast still has a negative area under the far right end of the righting moment curve, a cat-ketch with buoyant, nearly air-tight masts gains so much buoyant lever arm when they hit the water in a knockdown that it completely eliminates the negative side of the righting moment curve. See figure 3.

and we also get the full range of positive stability

Despite all these neat, nifty features, most people cannot get used to the idea that there are no wires holding up a free-standing mast. I'll get into why I think this is so in another design review. But to those people I say, "Do you ever fly, you know, like in an airplane?" (Most people have.) Then I say, "Well, the next time you are in a 747, we'll rig up some wires from the fuselage to the wing tips to make sure the wings stay on." Come on! Airplanes got rid of wires over 70 years ago. It's time sailboats did the same!

To see the ultimate cat-ketch rig, look at my website: www.sponbergyachtdesign.com to see Project Amazon, my open class 60 design that will compete in the Around Alone Race (formerly the BOC) in September.

The twin rudders are carbon fiber daggerboard-like blades, set in cylinders that turn. The cylinders are situated behind the transom in way of the scoop stern so that no joint or gland can leak into the boat. Twin rudder design comes from the single-handed racing boats, such as on Project Amazon which has this style of rudders. And this type of arrangement allows the windward rudder, which in normal twin installations is exposed to floating debris and damage, to be fully retracted. I also allows the rudders to be set deeper and run together if additional steering balance is desired. If a rudder does get damaged, it is easy to carry a spare (they are relatively lightweight and can be stowed on deck)--take out the broken section and put in a new rudder. You are steering again without having to do major hull repairs.

One of the features I like most about the Fast Passage 39 is its aft cabin. It lies to port partially under the cockpit. The door is in a longitudinal joiner bulkhead, so you face to port as you go through the door and stand next to the berth. The berth has a headboard and built-in night stand, and the space is quite comfortable and cozy. But in order to put a pilot house on such a boat, you need extra hull length for the chart table and inside helm, and still maintain an easy, roomy entrance into the aft cabin. I once tried to do put a pilot house onto an aft cabin layout on a 38' design, then on a 40' design, and both were just very cramped in the aft cabin. But on the Globetrotter 42, the extra hull length and correspondingly wider beam results in comfortable space for both the pilot house and the aft cabin. You get into the aft cabin through the bulkhead on the after side of the galley. Full headroom is obtained by putting the standing area in the aft cabin under the chart table in the pilot house. The inside helm seat in the pilot house is one end of a full-length berth. Put your feet into the cubby hole that stretches beneath the cockpit seat and settle in for a nice pilot house snooze. Note that the pilot house extends over the forward end of the cockpit, giving protection against the wind and spray to those outside. Standing in the cockpit, the top of the pilot house comes up to chin level on short people, so it is very easy to see over and forward. The entire cockpit can also be enclosed in a canvas dodger to fully protect it from inclement weather.

The space under the pilot house sole is doubly dry and roomy for the engine. Because the walkway through the pilot house is offset to starboard, and you would like to have the engine access hatch in the sole directly over the engine, so the engine is offset to starboard. The saildrive lower unit eliminates the need for a shaft, bearing, and stuffing gland.

Other nice features about the boat that would make it comfortable at sea are the shower in the head that doubles as a wet locker for foul weather gear (all wet space confined to one area of the boat located near the main companionway). At the aft end of the main saloon are both an entertainment center (catch up on those CD's or videos) and a fireplace, great for cold nights in northern climates.

If any of you would like to have a Globetrotter 42 for yourself, please contact me, and we can see about doing the complete boat design and getting one built for you. Ultimately, I would like to get this design into production so that I could buy one for myself. I call this a Globetrotter because that is what I want to do with it--trot the rest of the way around the globe.