Multihull Structure Thoughts

Re the Elfe, I captured the following off a website many years back...

 

Jamez. Thank you for the Elfe input, it helps a lot. I suspect your "library" is as extensive as mine.

 

It looks like a Silvestre Langevin drawing !

 

Today we have a look at Quad Marine “Quad 44” proposed electric catamaran in 2016/17. Steve Salani, CEO, has run several technology companies is the designer and developer of the idea. He engaged Mike Leneman (L-7 trimaran) to advise on the fiberglass structure and fabrication. The Quad 44 is 44 x 27.6 foot of an unknown displacement (calculated guess about 40,500 lbs). The hulls length to beam is 11 to 1. The draft is 3 foot over the hulls. The hull freeboard is 2 foot. Now we start to get into the hard stuff, the motive power. Little detail is available about the electric drive systems, but I will quote Steve Salani in a blog on his web site.

Steve Salani says “There is 25 square meters (260 square feet) of solar panels provide several kilowatts of power. An optional diesel generator is available for long cruising. Normally the boat has a range of 50 miles. As an option, an electrically rotating rigging with two main sails is available. With this system, the autonomy becomes almost unlimited.” Steve Salani also said “Total solar panel output should be at least 5 kilowatts in optimum conditions. The efficiency of solar cells is rising steadily, so we'll always use cells that offer the best combination of output and price.” There was a suggestion that the batteries could be Tesla Powerwall batteries.

The accommodation is large. There are 4 double berth cabins with full ensuites, a large main cabin with galley, very large seating area with a steering navigation area forward. There is a forward and aft cockpit arrangement with additional deck space for seating etc. There is formalised sealed dingy storage under the main cabin. Problem, the forward 2 double cabins are viable in bay sailing but would not be a great place to sleep in a seaway going upwind if you were prone to seasickness.

The structure beyond being foam fiberglass is unknown. Mike Leneman is a competent person but I do not know how much influence he has in the project.

Now we will discuss Steve Salani intention “The Quad 44 offers much more than just an alternative to outdated internal combustion engine propulsion. We've identified the design flaws and usability problems of traditional catamarans, discarded old ways of thinking, and devised innovative new solutions. The result is a totally new design that's fundamentally superior to traditional catamarans, with dramatically improved performance, safety, and accommodation space. The Quad 44 is the most advanced four-cabin cruising catamaran in the world! The patented raised-cabin design of the Quad 44 allows the lower hulls to be optimized for performance, with a narrow beam of only 4 feet that substantially reduces drag and increases speed. The upper main hull is optimized for passenger accommodation, with an astonishing 40% more interior space than typical catamarans. The four raised cabins are isolated from wave noise and cold water for a very comfortable cruising experience.”

The reality. The cat does not appear to be built. A battery range of 50 miles does not make an electric power cruising cat. Generators are internal combustion engines defeating the purpose of low environmental impact. The sailing rig is interesting but simple and is an addition, not the main motive power as the low hull freeboard and hull shape would not handle a high power sailing rig very well. The whole motive concept would need to be upgraded with 2021 technology which may improve things.

The final thing was the funding for the initial cat. This “production” cat was to be crowd funded with an initial boat to be delivered for $795,000 in 2017/18. The CEO was reported to be paid $180,000 in the first year. The crowd funding request was for initially $1 million. All of this sounded very optimistic.

I like creative ideas and this cat is creative but it needs development. The Silent range of solar power cats are much more refined and many are on the water. Also, there are several other companies that have proven solar hybrid cats out there doing long distance cruising. Take the Quad 44 for what it is an interesting idea. The jpegs tell part of the story.

 

After much searching.

Elfe 8 aluminium catamaran update. The designer is Bernard Veys at: https://www.enthousiaste.com/blog/accueil/catamarans-de-croisiere/elfe-8-01/

Elfe 8.01: Easy and comfortable cruising, just like in a 4X4!

Length: 7 m 90 - Width: 4m - Draft: 0m60 - Weight: 1500 kg - Sail area: 37 m² - Headroom: 1m45 / 2m - Number of berths: 5 - Engine: 8 hp - Construction: Alu

- Study file: 60 €

- File and Plans for amateur construction: 1500 €

- Construction time: 1000 to 1200 hours

He has also designed an aluminum cruising catamaran called the Elfe 10.51 that is 34.5 x 21.5 foot that displaces 12,000 lbs. His catalogue is at: http://www.enthousiaste.com/blog/wp...gue-bateaux-bernard-veys-architecte-naval.pdf

 

Regarding the Quad Cat… interesting that the hulls look to be built from one 1/4 mold. So, 4 pieces all from the same small mold to make up one hull. The cabin structure could be greatly simplified but should also relatively easy to build compared to something more boat shaped. The entire boat is a good idea that may benefit from newer tech. The styling could also be greatly improved, in my opinion.

 

The Argo from a few pages back reminded me of this boat, but it took a while to find the pic. Has hulls made from a 1/4 mold (to a Mitchel design IIRC). I think 3 were built 36-38 foot loa. Talked to a guy who owned one of them once who said it sailed well, by cruising cat standards.

 

Jamez. Sometimes similar boats appear and you wonder who thought of the idea first. Frenchman, Alexandre Fortabat designs both monohull and multihulls. His latest creation is the Balbuzard 45 Open (Balbuzard is French for Osprey) which is an open wing high performance cruising catamaran. The designer’s intention is to provide excellent seakeeping in all circumstances as the 45 makes “some express ocean passages”.

The 45 is 49.25 foot overall including the prodder, with a hull of 45.25 x 25.25 foot. The displacement is 15,000 lbs. The 59 foot carbon mast carries 1180 square foot of sail area upwind. The length to beam on the waterline is about 12 to 1. There is inverted bell type hull shape allowing increased accommodation in the hulls. There is no indication of the rudders or foils but the Balbuzard 35 foot version has deep daggerboards, and I would assume a similar arrangement. The underwing clearance is large. With the numbers above, the simple performance calculator says this cat will see above 20 knots on many occasions and be capable of 200 to 300 miles days in good conditions.

The power system is hybrid hydro-generator electric propulsion with solar panels, to allow a longer range.

The accommodation is good for an express cruiser. There are 3 double berth cabins and a single berth cabin in the hulls. There is a bathroom in each hull. In one hull is a good sized galley, in the other hull is a seating and a navigation with entertainment area. The open cockpit with a bimini has a dinette area. The raised helm stations are positioned aft of the hull coachroofs. The intention of this cat is to sail in warmer climates.

The construction of the 45 is environmentally friendly with a low carbon footprint. It uses natural materials – wood, flax fiber, cork based core materials and bio-sourced epoxy resin – facilitating the build for the majority of the spread-out surfaces (translation: flat panel construction for the majority of the cat). A kit for amateur construction is in the design stage. All possible but will require a learning curve.

An interesting fast cat. The jpegs show the proposed but realistic Balbuzard 45 Open. The last jpeg is a proposed wing version of the Balbuzard 35.

 

This is about a special purpose catamaran that was designed by Darren Newton of Dazcat to suit a disabled sailor who wanted an expedition catamaran for exploration and diving trips. The owner’s broken neck resulted in him being confined to a wheelchair. Being a creative and active guy, he designed a self propelled wheel chair that had almost 4 x 4 capability and wanted a boat that would allow him to sail to great diving locations for his favourite hobby. Dazcat has produced a disabled large cat previously and used that experience to develop a more flexible solution in this cat.

Artemis is 52 x 26 foot with a built weight of about 19,000 lbs displacement of about 25,000 lbs. The mast aft rig has a 60 foot mast with 2 roller furling headsails. The inner headsail is a self tacking of 670 square foot and the outer is a genoa of 950 square foot are both are on very good quality electric furling forestays. The sheets for each are attached to electric sheet winches. The rig is designed to allow the cat to be sailed almost single handed by a person of limited mobility. The hull length to beam is about 14 to 1. The draft is 4 foot with delta low aspect ratio keels and fixed spade rudders. The underwing clearance is 2.7 foot. The hull shape is interesting and a extension of the shape used on other Dazcats. The waterline is narrow with bulbous flares above the waterline to increase the space in the hulls and reduce the width if the bridge deck which improves the strength of the structure.

The accommodation from the forward beam aft has a flat deck to allow the wheel chair to move around. There is a small lift to allow the owner to move onto the foredeck. The bridge deck cabin has the galley, navigation, dinette, wheelchair friendly bathroom and owners sleeping cabin. There is 3 additional double berth cabins and toilets in the hulls. There is deck storage for diving gear, compressors etc.

The decks are designed to allow access by the motorized wheel chair and the aft hull decks were extended to allow access to the specially designed dingy. The dingy has a fold down front access door for wheel chair access.

The cat is a PVC/ Glass (probably vinylester resin) structure with carbon fibre reinforcements in high stress areas. There are some video’s on the Dazcat website showing some of the build shots. Flat panels feature a lot but the hulls are very rounded. This is not a cheap boat and would be well over 1 million pounds (over $1.4 million US).

The performance of this cat will be good, but outright performance is not the primary goal. Good seakeeping, maintaining a steady platform and have a moderately easy rig to handle are the primary goals.

An interesting design that is currently serving its purpose well. The jpegs give the idea. The final jpeg is a “concept” design of a similar sized conventional cat.

 

How does one “like” a post on this forum? There are many things that I think are awesome and I’d like to let the author know so. Posting a replay that says that’s really interesting or cool or whatever will just clog up this amazing thread.

 

Like this on mobile.

 

Iridian explains it very well above - and I just clicked on the like button on your post.

 

Today was a case of confusion as 2 design companies were claiming to be the designer of the same cat. But confusion was resolved when I found this line. “Construction Engineering: Morrelli & Melvin, CA; High Modulus/Gurit, NZ; Kernan Yacht Design, CA”. So, I will take the design concept as being Kernan yacht design with Morrelli & Melvin the structural engineers.

The cat being discussed is “Water Wizards” a long range 50 foot power catamaran intended for film and TV work. The cat is 50.5 x 18.7 foot that displaces between 28,000 and 31,000 lbs depending on what designer web site you go to. The cat can carry up to 4500 lbs of camera etc gear as well as 10 crew. The draft is 3 foot. The power is twin Yanmar 480 hp with Hamilton JetDrives 332 equipped with Blue Arrow.

The performance is interesting with a peak speed of 32 knots. But with the 2000 gallons of installed fuel the cat can travel 2000 miles at 25+ knots and 6000 miles at 12+ knots. Greater speed and range is available with the use of its 2 optional fuel bladders. With the installed jet drives the vessel is very manoeuvrable capable of spinning in its own length.

The structure is high density foam vinylester composite which is vacuum bagged. Carbon, Kevlar and Ultra light Balsa is also used throughout the structure. A lot of the structure uses flat panel construction.

The major advantages of the design for its filming TV task is: Runs level at all speed, allowing better alignment of horizon line, and comfort on board.

• New tight weave net with new anchoring for minimum spray on deck.
• 3 level filming platforms: 1ft, 6ft, 9ft above waterline.
• Flexible deck for various rigging, tracks and tie downs for on-deck equipment (giro stabilized cameras, IMAX equipment, cranes and booms, etc).
• Removable 42 inch tall lifelines and stanchions for low shots, or installation of camera rails.
• Makes a 360 degree turn on its own length without wake.
• Light grey hues to lower glare on deck.
• Inside protected areas for working on cameras, filming equipment, charging batteries.

An interesting cat that has been successful in its task. Tomorrow I will feature the “cruising cat” versions of this design. The jpegs tell the story.

 

That's a pretty interesting boat. The range and speeds are almost hard to believe, especially as it's only 50 feet. They must have kept it light.

 

Yesterday’s Water Wizard cat inspired another group to request a long distance cruising power catamaran design from Kernan Yacht Design. The Journey Cat 47LRC was the result. The 47LRC is 47.5 x 18 foot with a fully loaded displacement of 37,500 lbs. Twin 260hp Yanmar diesels spinning 24-inch diameter props will be standard shaft drives. The fuel tankage is 680 gallons (2580 litres) spread over 4 tanks held down low in the hulls. The draft is 3.5 foot at half load. The hull length to beam at the waterline is 14 to 1.

The wave piercing bow allows the boat go through the wave instead of riding up and then down over the wave. This particular hull design does not have the dynamic buoyancy that you find in most vessels, in other words it does not produce noticeable lift when running, hence keeping the boat flat and smooth through choppy conditions. This reduces stress on the vessel and the crew. This design also has the benefit of reducing the boat’s wave making resistance which means she goes through the water easier, equating to better fuel economy. There are twin keels that are cutaway aft to feed clean water to the props, help protect the running gear, and optimize tracking. Tunnels help to minimize draft and improve the drive angle of the engines

The performance is a cruising speed of 7 to 17 Knots with a top speed 22 – 23Knots. The fuel economy is 2.5 nautical miles per gallon at 7 knots, 2.0 nautical miles per gallon at 9 knots and 1 nautical miles per gallon at 16 knots. At top speed 0.8 nautical miles per gallon at 23 knots. With the 680 gallons of fuel, the 9 knot cruising range is 1360 miles and at 16 knots the range is 680 miles. This is an impressive range for a production cat. There can be additional fuel tankage ordered for those wanting really long-distance cruising.

The accommodation has 3 queen berth cabins in the hulls with 2 full size bathrooms with fresh water toilets. There is also a pantry/work room for maintenance. The engines are in separate rooms allowing access for maintenance. The main bridge deck cabin has a large galley, navigation steering position and seating with a table for many crew. The cockpit also has fish cleaning sink. The outside steering position is a flybridge arrangement with a spiral staircase from the cockpit.

The structure has major components of the hull and deck built using a resin infusion process. Initial layers are vinylester resin followed by alternating layers of bi-axial, uni-direction stitched roving/mat and Taiwan Glass mat. Above the waterline, Corecell structural foam core material is used in the hull, as well as in the superstructure, to create a stiff structure, which is reinforced by longitudinal stringers and multiple transverse frames. The hull-to-deck joint is sealed with adhesive, stainless steel bolts, and an inner lamination of fiberglass. The deck and bulkheads are fiberglass and structural foam infused panels. Bulkheads stand off the inner hull skin with pyramid-shaped foam blocks, and are heavily glassed in place to help spread weight and torsional loads. Windows are tempered glass 12 mm all around, except for the sliding door, which is 9 mm thick.

A good design that has proven to meet it requirements in boating tests. The fuel economy quoted above are from actual test results. There is a proposal for a 53 foot version soon. The jpegs give part of the story.