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High school project with a difference. The story of building 2 Shuttle 31 catamarans.

By John Shuttleworth.

Shuttle 31 sailing video

Video of Shuttle 31 Planado sailing fast offshore.

Shuttle 31 video click on image for Shuttle 31 sailing video.

In July 2000 I received an order for a set of plans for a Shuttle 31 to be built in Western Red Cedar strip planking with Epoxy and glass reinforcing. I had been in correspondence with the teacher of a group of young people at a Waldorf (Steiner) school in Switzerland. This teacher, Thomas Wolf, intended to head up a team of 12 students with the aim of building two 31 ft cats in less than two years. At the start of the project the students wrote to me “We are twelve students at the age of 16-17 years. We attend a Waldorf school in Muttenz, Baselland. Two afternoons per week we work at the boats. While our schoolmates attend special courses like working on a farm, we will solely concentrate on building the boats. Also during the holidays we will sacrifice some weeks for the project.”

When they finished building they planned to sail the boats down the Rhine into the North Sea, and on to the Mediterranean, where the boats were to be based. They would also be involved in raising sponsorship, and producing a web site, and would all get their Swiss equivalent of the yacht masters certificate, so that they could skipper the boats when taking out other students on environmental educational cruises in Elba.

I thought it was an amazing project for a group of students, and I knew that there was a lot to learn and do in less than two years. I sent off the plans and the project began. I was never in any doubt that the boats could be built. The Shuttle 31 is ideally suited to strip planking in either Core-Cel foam or Cedar, and the plans are very detailed. I provide backup as part of the package, and my experience with homebuilders indicated that my plans are so detailed that there are often only a few points to clarify along the way.

The web site www.fossailing.com duly appeared which meant that we could follow progress on the site. As the months went by the boats took shape and looked very good. Questions would arrive by Email, and the students who spoke English best undertook the task to communicate with me. Thomas Wolf’s son Florian, took a key role in the project even though he had left the School to undertake further qualifications elsewhere.

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Fig. 1. The Fossailing team. Thomas Wolf is third from the right.

I am sure that the design would have provided considerable interest to the students from a technical point of view. Although it is relatively straightforward to build one of these boats, there is a wealth of technical thinking and detail in the drawings which would have provided a lot of additional learning opportunities for the students in understanding the loads in the boat and how the structure is made to take them. So they would not only be learning craft skills, but they would also be developing an understanding of how to think about structures. Dale Schnieder told me that one of the highlights of building my designs is that the technical aspect is so interesting, and that his building team particularly enjoy this aspect of building the boats. Once the ideas behind where I place the fibres, becomes clear the whole design concept makes sense in quite a straightforward way. This makes the boats very interesting to build.

The actual building process.

The first task was to build the mould frames from the full size computer lofted patterns I provide, and set them up on a strongback at the correct station spacing. For the Cedar boat I suggest building the hull on the outside of the hull lines. This has the effect of adding 15 mm to the hull and increases the buoyancy to account for the added weight of the wood.

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Fig. 2. The hull frames are set up on the strongback. Only one mould is needed for both hulls.

The frames are made from 20 mm MDF or cheap plywood. Once they are set up the hull planking begins. 50 mm wide strips of Western Red Cedar were edged glued and screwed to the frames. Eventually the screws are removed and the holes are filled with epoxy during the glassing stage. Details of this method can be found in “The Gougeon Brothers on Boatbuilding”Pendell Printing Inc. ISBN 0-87812-166-8

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Fig. 3. The 15 mm thick Cedar planks are attached to the mould frames. and edge glued to each other with an adhesive epoxy mix.

The planks are fitted carefully before gluing, and the hull shape develops very quickly.

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Fig. 4. The planks are carefully fitted at the ends.

When the hull is fully planked the surface is sanded to a smooth fair finish with a coarse sandpaper. One layer of biaxial glass is applied all over the outside of the hull, and extra reinforcing is added as shown on the plans. The fibre direction is important, for the ”integrated structure” and arrows on the plan show how to lay up the layers. Once the glassing is complete, the hull is sanded. Finally the hull is lifted from the mould and set into a cradle

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Fig. 5. The first hull is lifted from the mould.

The Fossailing team decided to split the hull and deck at the sheer line, and so the decks ware built separately. Figure 6 shows the students laminating the biaxial glass into the inside of the deck. By taking care at this stage, the team achieved a surface that was good enough to leave as the final interior finish. This has meant that the inside of the boat has a lovely wooden feel.

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Fig. 6. Glassing the inside of the deck.

Figure 7 shows the deck glassed on the inside and outside, ready to fit to the hull. Figure 8 shows the inside as the deck is fitted. The edges are glued together, and layers of biaxial glass are laid along the join, inside and out.

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Fig. 7. Deck ready to fit onto the hull.

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Fig. 8. Final fit of Deck to hull.

Bulkheads can be made ahead of time, In this design they can be plywood or foam sandwich. The Fossailing team decided on foam sandwich and figure 9 shows the first bulhead cut out and ready to be glassed and then fitted in place.

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Fig. 9.

Bulkheads are attached to the hull with an epoxy fillet, and layers of 45 degree glass fibre. The drawings show how each panel is connected into the hull, with the exact width and weight of glass required. These connections can be laminated on a plastic sheet outside the hull, and then the whole connection is laid into the corner 2 ft lengths. This method reduces the mess that can occur when glassing in the interior components, and allows for better resin to glass ratios. Keeping the hull clean inside means less time spent at the final finishing stage.

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Fig. 10. Glassing in the bulkheads and berths.

The finished hulls can be seen in Figure 11. Note the added foam bows for protection against collision. On impact the foam bow is designed to collapse back to a strong wooden bulkhead about 300 mm back. This absorbs the load and should prevent flooding. If the wooden bulkhead is breached, there is another watertight bulkhead 6 feet further back.

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Fig. 11. Hulls ready for the bridgedeck construction to begin.

Figure 12 shows the bridgedeck sole being fitted. The sole is made in foam sandwich because it is light and stiff for the large unsupported panel area. Airex foam is very good in impact for the odd occasion when a wave might slam up under the bridgedeck.

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Fig. 12. Preparing fit the bridgedeck sole.

With the hull complete, the interior is fitted. Combinations of foam sandwich and wood veneers, produce a comfortable and beautiful look. The interior is fairly simple, with lots of locker space, and large comfortable berths.

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Fig. 13. Companion way to galley.

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Fig. 14. Saloon table, drops down to make a double berth.

The inside of the hull is left with the wood showing. The lines of the wood enhance the curved shape. Note the aluminium backing plates behind the fittings. At highly loaded fittings layers of unidirectional glass fan out into the hull or bulkheads taking the loads away from highly stressed areas into the body of the boat.

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Fig. 15. Aft cabin.

Sailing trials.

The day finally came just under two years since I posted the plans to Switzerland, when I was asked to go to Calais in France to help them sail the boats to Cowes on the Isle of Wight, England. This sail was to be part of extended sailing trials to fully assess the boats, and to help teach the crew about Multihull sailing.

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Fig. 16. The boats finished and ready to go in Calais.

After sailing from Calais to Cowes, I spent three days sailing the two boats in the Solent in a variety of conditions. The boats are well built and look fantastic. Both boats sport the racing rig with Gougeon wing masts. "We chose Gougeon because they were the only masts we could build ourselves" said Thomas Wolf.

The Fossailing team have clearly demonstrated that the Shuttle 31 is a good boat for amateurs to build. They chose to use my design for strip planked Western Red Cedar with glass fibre on both sides and although I predicted that they would add about 230 Kgs to the weight of the boat over a foam sandwich version. They are sure that they have added less weight by being very careful in the laminating process. The boats float on their marks and perform very well and we achieved 8 knots to windward tacking through 85 degrees, easily outsailing any monohulls that we came across in the Solent as usual. I have enjoyed the experience of sailing with this enthusiastic group of young people and I would like to take the opportunity to congratulate them all on a fine achievement. The boats look good, and I am sure they will have many years of enjoyable and fun sailing on them."

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Fig. 17. Sailing at last

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Fig. 18. The huge cockpit of the Shuttle 31.

The 9.9 HP 4 stroke outboard is mounted under the cockpit table

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Fig. 19. We pass a piece of history as we enter the Solent.

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Fig. 20. Slipping along at 7 knots in hardly any wind.

The teams sailed the two boats in the Solent near Cowes for a few weeks to fully prepare themselves for the trip to Elba. They sailed across the English channel, through the Bay of Biscay, down the Spanish and Portuguese coasts, and into the Mediterranean. They arrived safely in Elba on September the 23rd, having covered 3500 miles. A very successful end to an amazing project. Read more about the project at www.fossailing.com

About the Shuttle 31, Wood Epoxy or Foam Sandwich Cruising Cat.

This 31ft catamaran is part of a range of fast cruisers which developed from the highly successful Spectrum 42. Designed and engineered with the latest thinking on structures and computer designed hull forms, the boat is nevertheless suited for skilled amateur construction.

The Shuttle 31 was the 10th design in a line of development that started with the Spectrum 42, which itself represented a major advance in cruising catamaran design.
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Many of these boats have offshore passages behind them, and the features of exceptional pitch damping and bow slightly raised on a reach have been well tried and tested, and have proven to be outstanding features in improving general cruising comfort at sea, along with greater safety and fine seakeeping qualities. (Ref 1) (Ref 2)

There are now 5 boats in the series which all have similar styling, namely the Shuttle 28, Shuttle 31, Tektron 35, Shuttle 40, Tektron 50. There are also cruising versions with a bridgedeck saloon at 30, 37, 40, 43, 50, 52 and 63 ft LOA.

One of the main aims of this new design was to produce a boat of outstanding comfort and living accommodation space, with as little sacrifice as possible to the excellent sailing performance, windward ability, and seakeeping qualities of this well proven type of hull form.

Apart from the great benefits that can be derived from flaring the hull above the waterline, in terms of keeping the bow up on a reach, the flare gives a massive increase in interior volume without increasing the windage of the hulls at all. For instance, above the waterline the hull flares outwards to give a maximum beam at eye level of 1.95m (6'4"), the impression of space is tremendous and cannot possibly be matched by any similar length catamaran whose topsides rise almost parallel from the waterline.

Construction and long term fatigue.

By using integrated structural techniques the hull weight can be carefully controlled and the net effect is a strong, light displacement hull with a high long term fatigue life. Integrated Structure is a computer aided design method which I originally developed for the highly stressed ocean racers of the North Atlantic circuit. The structure of the boat is designed in a similar way to a sail where highly loaded areas like reef points and clew are patched out into the lighter body of the sail, the layers of cloth increasing from the lighter body of the sail out towards the clew or reef cringle. (ref 3,  ref 4). This is achieved by laying unidirectional fibres along the line of greatest stress in highly loaded areas, and spreading the fibres into the body of the hull or deck until the stress is distributed over a large enough area to ensure that structural failure of the boat itself is virtually impossible. Fibre quantities are carefully calculated to avoid any stress build up in the structure at vulnerable points, thereby increasing the fatigue life of the boat dramatically.

Windward Performance.

Recent research (ref 4) has shown that windage is the largest component of drag for a light multihull. The rounded decks and streamlined shape significantly reduce the drag of the boat through the air. Bear in mind that on a sailing boat the wind is never blowing directly from ahead, rather it blows across the hull, at a minimum of 30 degrees off the bow.

The Shuttle 31 has excellent windward performance because the boat is relatively light, with efficiently shaped daggerboard and rudders. And most importantly, she has low aerodynamic drag, with a very efficient rig.

Engine.

A single outboard (which can be steered) is mounted in the centre of the cockpit in a lifting box under the table. A Yamaha or Honda 9.9 HP outboard will push this boat at 8 knots. The outboard box lowers and the outboard kicks down when in use, and when retracted there is no propeller in the water to cause unwanted drag, and no holes through the hull. In the cockpit the box doubles as a table. It is possible to install 2 outboards, one each side of the cockpit if more control at very slow speeds is required, but so far all the boats have just used one engine on the centreline.

Rig.

A wing mast has been chosen as the standard rig (although other options are available.) A wing provides a very efficient and simple rig, which can be home built. Gougeon brothers provide plans for Wood Epoxy masts and I can provide plans for carbon wing masts. The high aspect jib is self tacking, which means no winching or flogging lines when coming about which is fantastic for cruising! The mast size is designed so that the mast itself becomes the storm sail in the most severe conditions.

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Fig. 21. Sail plan.

Accommodation

The Accommodation is straightforward and spacious, with the saloon aft in the port hull. 2m (6'7") long and 2.3m (7'6") wide at eye level. The flare in the hull makes his a very spacious and comfortable social area. Ford of the saloon is the 1.9m (6') long galley with ample space for storage and food preparation. The single daggerboard, with our special kick up system, is unobtrusively canted towards the hull side at the ford end of the galley. In the bow is a forward stateroom with a large double bunk. 2m ( '7") x 1.35m (4'6"). Ford of the berth in each hull is and anchor locker or sail stowage.

The starboard hull aft has a very big double berth 2m (6'7") x 1.6m (5'4"), with good locker space and standing area for dressing. Next is a fair sized chart table, and oilskin locker with a separate W.C. / shower area. The forward area is the same as the port hull.

On deck, all controls lead to the 3.2m (10'6") x 3.6m (11'9") cockpit, and with the mast standing on the main structural beam at the forward end, there should be few reasons to leave this safe area. Reefing is carried out while standing by the mast, and sail controls lead to near the helmsman, making this boat very easy to single hand. Spray dodgers over the entrance hatches protect the helmsman from spray, a system that has proven to work well on a number of boats. A tiller extension connected to the centre of the tiller bar, gives the helmsman considerable choice of where to sit. Visibility of the sails and forward is very good, which will increase the enjoyment of sailing this exciting performance cruiser. A permanent Bimini has been designed to cover the cockpit for sailing in areas like Australia and Florida where permanent shade is required. Displacement in racing trim is 2.2 tons with an additional cruising payload of 1.25 tons.

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Fig 22. Accommodation plan.

Building Plans.

The full set of building plans consist of 20 very detailed drawings, and full size computer lofted frames for building the mould. The study plan is $ 10.00. A basic materials list for the glass and foam or wood for the hulls, bulkheads, and bridgedeck is available.

References

1. Spectrum 42 - New Production Cat. John Shuttleworth, Multihulls , March/April 1985.

2. 35ft Catamaran, John Shuttleworth, Multihulls Magazine, Jan/Feb 1985.

3. Cruiser/ Racer Multihull Design. John Shuttleworth, Multihull International November 1985, and 2nd Multihull Symposium talk, Annapolis 1985

4. Beyond the Tektron 50…the design of the new Dogstar 50. John Shuttleworth Multihulls. March/April 2002

5. Multihull Design for Seaworthiness. John Shuttleworth Multihulls. Jan/Feb 1988