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Decades in the making

Jan 1, 2003

At Boston, Mass., in 1767 a schooner named Sultana was built. In 1970, long after Sultana was history, a Cape Cod auto mechanic named Larry Mahan saw a drawing of her that completely changed the next 30 years of his life, the lives of his family, and the lives of numerous other people who knew him as well.

Since grade school Mahan had wanted to build a boat and go to sea. Starting in 1968 Mahan had been studying historical drawings of the beautiful early colonial sailing vessels. They so delighted him that he yearned to build a reproduction of one. He wanted a vessel of moderate size but with ample cargo space. He also wanted it large enough to live aboard. When he saw the Irving L. Chappelle drawing of Sultana, bells rang! He decided he would build a replica of that boat.

For many years before he came across the drawing of Sultana, Mahan had been doing has homework on boatbuilding in general and the construction of historical replicas in particular. Replicas of wooden-hulled vessels have normally been built using as nearly as possible the same materials used in the original vessel. These replicas generally require extensive repairs at fairly regular intervals. A replica of Mayflower is a good example. Launched in 1956, she has required extensive and expensive repairs about every 15 years. Most other wood replicas have had similar problems.

There are three serious disadvantages with wood as a material for building ship hulls. The first is that wood is highly prone to infestation by the fungus causing a wood decay called dry rot. This appears to be a misnomer since this fungus multiplies only in moist, poorly ventilated areas, but it came to be called dry rot because it reduces the affected wood into a dusty dry powder.

The second disadvantage of wood as a hull material is that below the waterline wood is prone to infestation by a marine borer or shipworm called the teredo. This creature riddles the underwater wood with small tubular channels similar to what termites do to wooden buildings on shore. Chemical treatments will slow dry rot, and toxic paint will slow teredos, but nothing can totally stop deterioration of wood hulls from attacks by these two enemies. In addition, there is a third drawback: wood is readily destroyed by fire. Alternative hull material

Mahan's investigations revealed that an alternate hull construction method called ferro-cement had successfully been used to build vessels in a wide variety of sizes and types both larger and smaller than the boat he had in mind. Ferro-cement for hull c?nstruction had three immediate and immense advantages over wood: it is impervious to dry rot, it is impervious to teredoes, and it is completely fireproof.

The post-World War II work of Pier Luigi Nervi, the noted Italian architect and engineer, had laid the groundwork for the lively interest in ferro-cement for boatbuilding that developed in the 1950s and 1960s. The present-day boatbuilding applications of ferro-cement would have been impossible without his extensive and successful pioneering work.

As an architect he became particularly well known for the design of buildings such as aircraft hangars and warehouses containing extremely large open areas covered by roofs with no interior supporting columns. This he accomplished by constructing an elaborate steel reinforcing mesh that was then coated inside and out with a thin layer of lightweight concrete. The result was a light but extremely strong steel and concrete roof shell. This construction method was named ferro-cement from the two component materials employed: the ferro referring to the steel reinforcing network and cement to the concrete coating. As a side interest Nervi had also pioneered the use of ferro-cement in boat construction. He designed and built a large yacht on which he vacationed extensively in the Mediterranean.

Very quickly this method was recognized as a far more durable alternative to wood for building boat hulls; it was also a less expensive alternative to fiberglass, which was becoming increasingly popular since it is impervious to both dry rot and teredo infestation. However, fiberglass does burn quite merrily.

Ferro-cement was initially promoted as a material particularly suitable for the amateur boatbuilder because it was claimed that the elaborate equipment and highly developed skills required to build a wooden hull were not required. This was a misconception, and unfortunately it proved to be the kiss of death for ferro-cement.

A great many enthusiastic amateur builders with little or no nautical experience rushed forward with the construction of a large number of outstandingly unsuccessful boats. Although many very good ferro-cement vessels were built by both amateurs and professionals, they received less publicity than the many amateur disasters. A poor reputation

These failures gave ferro-cement a poor reputation in the boating world. The reason in most cases was that these amateur builders were not accustomed to working at the level of accuracy required to produce a smoothly finished hull. Accuracy requires time, making ferro-cement work labor intensive.

Although Sultana was, of course, originally a wood boat, Mahan concluded that in light of the drawbacks inherent in wood he would build his replica with a ferro-cement hull. At the start of his project Mahan had very little direct practical background in boat construction. His first experience with ferro-cement came through working on the ferro-cement reconstruction of a wooden powerboat. Subsequently he gained the necessary experience by working on a number of other ferro-cement boats.

Ferro-cement differs significantly from what one normally thinks of as reinforced concrete. It requires an elaborate steel armature composed of wire mesh and steel rods that form the fundamental support structure, which is then embedded in a thin layer of carefully formulated concrete to form a thin but extremely strong shell that is the hull of a ferro-cement boat.

Mahan bought a house with a large yard in Marston Mills, Mass., a small town on Cape Cod. Here he could build his boat in the privacy of his own backyard, where he could work on it whenever he chose. It was 1970 when he started construction. Although Mahan did not start out as a highly experienced boatbuilder, he had specifically studied and worked with ferro-cement for a long time. Also, he had an extensive technical background in automotive mechanics. His training and experience in this field familiarized him with technical drawings and with accuracy in measurements and dimensions.

Based on his extensive background in automotive technology, Mahan knew that in order to successfully build a large ferro-cement boat he needed to become an unquestioned expert in that technology. He pursued it with such diligence that within a couple years time he had become sufficiently expert that articles by him appeared in technical journals on the subject.

A ferro-cement construction, whether it is a boat hull or one of Pier Luigi Nervi's open auditorium roofs, is done basically in two stages. The first is construction of the steel framing and support system, which is then covered with a steel mesh that supports the contours of the final shell. Second is the application of the cement coating that completes the shell. Set up with extreme accuracy

In the case of a boat hull the lines of the finished hull can only be as smooth and fair as those of the underlying mesh and its supporting framework. This is exactly where so many of the eager but unskilled amateur builders went awry. The support framing and its mesh overlay must be set up with extreme accuracy, after which frame and mesh must be very securely fastened so that when the plastering is done the very considerable added weight of the cement does not deform the support system. This would result in a misshapen hull. In his many examinations of existing ferro-cement boats, Mahan had seen plenty of cases in which this exact thing had happened.

The first step toward constructing a ferro-cement boat is building wooden scaffolding to support the metal frames. This initial scaffolding has to be extremely accurately aligned, leveled, and braced. In Mahan's case the main frames were made of steel pipe. Each pipe frame then had to be bent absolutely accurately. Mahan says that it took him a day and a half to get the first frame bent correctly.

The frames were then aligned and secured to the scaffolding. A combination of chicken-wire mesh supported by steel reinforcing rods were then added to define the final shape of the hull. It is this combination of mesh and reinforcing rods that makes possible the comparatively thin layer of cement that is used in ferro-cement construction. Firmly connecting the supporting metal layers to each other is an extremely tedious and time-consuming job. Mahan estimates that altogether it took about 360,000 individually placed wire connectors to complete the steel reinforcing network. Mahan worked away at this job with the help of his family from 1970 for the next six and a half years until the happy day of July 25, 1977.

This was plastering day. On this day starting at 0700 a volunteer crew of 130 people that Mahan had gathered started applying cement to the elaborate steel web he had taken so long to prepare. The preparation of the steel reenforcing network can be done as quickly or, as in Mahan's case, as slowly and deliberately as the builder chooses. However, the plastering is quite another story. The plastering of the entire 60-foot hull had to be completed in one day, and it was. An exhausted crew completed the job by 1800 the same day.

A full explanation as to why the plastering of the hull had to be completed in one day requires a rather arid discussion of the chemistry of cement. Suffice it to say that chemistry dictates that the plastering be done in one continuous operation to ensure the uniform strength of the cement coating. This is why Mahan, who up to now had worked for years in no particular hurry with very few helpers, had assembled such a large crew in order to be certain to get the plastering job done in a single day.Fill all voids

The mortar that is used must be carefully and thoroughly worked into and through the layers of reinforcing mesh to ensure complete penetration. Care must be taken to ensure that all voids are entirely filled. This job requires that the people involved have at least minimal manual skills, and that they pay careful attention to what they're doing. It is not easy to produce a quality plastering job, but it is very easy to ruin one.

When the plastering was completed the cement was then cured for close to a month. With curing completed, the hull was then sealed, smoothed, and finished. After six years of work Mahan now had a hull, but he was still a long way from having a complete boat - a great deal of work remained to be done.

Much of the finishing and fitting out was done in wood. As already noted, while wood is not the best material for the hull, which is in contact with the sea, for the many parts that are not directly in the water wood is, and always has been, an excellent material. The immense amount of interior and exterior woodwork that was needed was done partly by volunteers and partly by hired help. The wood used throughout was salvaged antique lumber from old buildings in Boston the surrounding area. Beautiful old hard-pine timbers were recut and reworked to make the deckhouse, deck rails, hatches and hatch covers, bunks, lockers, drawers, interior bulkheads, stairways, and paneling - all the various interior and exterior parts needed to complete the vessel.

In the late 1700s all vessels carried a beautifully carved figurehead at the bow, so Larinda required one as well. Mahan's wife, Marlene, has a particular fascination with frogs, so when it came to designing the figurehead it became a frog. He was carved by a neighbor, Susan White, from a 100-year-old block of cypress and appeared with a proper 18th century naval hat and telescope. White also did the name plate and decorative carvings on the transom, as well as additional decorative work on deck. The transom carvings include the name of the vessel, above which is a large scallop shell flanked on both sides by two black-and-white killer whales.

While the exterior and interior woodwork was underway Mahan looked for an engine. Getting and installing the auxiliary engine turned out to be another major project. Mahan wanted a power plant powerful enough to move the boat at a respectable speed, and it had to be robust, absolutely reliable under adverse conditions, and technically simple for ease of repair. Of course also it had to be a diesel rather than a gasoline engine.A classic diesel

Traditionally, diesel marine engines have been larger and heavier than gasoline engines of similar horsepower because of the higher compression required. However, in recent years the emphasis in the development of marine diesels has been toward reducing weight and physical size, making it easier to use them in place of gasoline engines These smaller engines turn at somewhere between 2,000 and 2,500 rpm to reach their rated horsepower. Mahan wanted a big motor to turn a large prop at slower rpm. After exhaustive research he finally decided to use a big, heavy old Wolverine diesel. The catch was that the last Wolverine engine had been built in 1950.

After a long search he finally found one in 1979 - a massive 1928 four-cylinder, 100-hp model that reaches its rated power at only 350 rpm. This engine had to be completely rebuilt, which took another 10 years and sent Mahan all over the U.S. and as far as Central America looking for usable parts. For example, he found the 1,500-pound flywheel that is now on the engine in a junkyard on Staten Island. After being rebuilt, the seven-ton engine was finally moved during the summer of 1992 from Mahan's shop in Hyannis to the boat in his backyard at Marston Mills where it was installed in Larinda. By this point Mahan had been working on his boat for 22 years!

A marine engine is normally hidden out of sight in a separate engine room. There was no way an engine of this size could possibly be concealed in an engine compartment on Larinda, so Mahan prettied it up and located it in the center of the main cabin.

In January 1994, 24 years after starting work, the boat was nearly ready for launching when the fates dealt Mahan a dreadful blow. At his shop in Hyannis a 150-gallon heating oil tank had rotted out from the inside and spilled its contents over a large surrounding area. This was an accident not covered by insurance, so both his time and his bank account were completely swallowed up in the process of cleaning the huge resulting mess.

The cost of the cleanup was about $40,000. To help defray this expense Mahan did several lectures, and he and local friends held fund-raisers, but for a period neither time nor money were available to advance work on the boat. It was difficult enough simply to maintain everything as it then was until work could be resumed.

As Mahan had demonstrated repeatedly over many years - sometimes he can be slowed, but never stopped. The oil spill was cleaned up, the heating system at the shop was changed from oil fired to gas, and the boat project resumed.

Up to now during the many years the boat had been under construction Mahan had continued to operate his automotive repair business. Finally, in early 1996 he decided he'd had enough of doing two jobs, so he closed his repair shop to spend full time on the boat.

At last in September of 1996, after 26 years under construction and amid great celebration, Larinda was launched at Falmouth, Mass. Many of the hundreds who had helped to build her along with hundreds of additional spectators were on hand. In addition, there was a squad of militia in Colonial military uniform armed with muskets and a fife and drum corps as well. The attending crowd was estimated at about 2,000 people. Lugsail rig chosen

With the boat finally in the water she still had to be fitted out with masts, rigging, and sails. The old 1767 schooner Sultana was rigged with a combination of square and fore and aft sails as was normal at the time she was built. Looking at that sail plan Mahan decided that it would require a larger crew to handle those sails than he could normally expect to have aboard. If he were to go to one of the more modern schooner rigs using all fore and aft sails, like a staysail schooner rig, he would still need a large crew to handle the sails.

After much deliberation, he decided that, although it would be a radical departure from the original Sultana, by far the simplest and easiest sail plan to handle would be similar to that of a Chinese junk. The Chinese lugsail is easy to control, and he would need only two of them and a jib, minimizing crew requirements.

When under full sail on Cape Cod, among a group of contemporary sailboats, Larinda may look rather odd, but Mahan has found she sails well and is easy to handle. In a fair breeze she'll do between seven and eight knots, which while a bit under her nominal hull speed allows her to get where she's going in a reasonable length of time and provides a far more comfortable ride than many vessels of much newer design.

After 30 years spent building his boat, Mahan is using Larinda for charters, excursions, special events, and educational purposes.While capable of going offshore, Mahan has no immediate plans to do so. With a hull that is impervious to rot, shipworms, and fire, and baring any gross navigational errors, Larinda is certain be around for a very long time.

Contributing editor Jeff Markell is the author of Sailor's Weather Guide, published by Sheridan House. He sails his Coronado 35 out of San Diego.