Multihull Structure Thoughts

Scarab Siren 8.4

Plans for8.4 catamaran http://www.teamscarab.com.au/8.4Des.html

 

The following is a more detailed update on 3D printing mold production for a catamaran hull. ORNL and CI teamed up with industry partner Alliance MG, LLC (AMG) to explore the feasibility of 3D printing a boat hull mold on the BAAM. This 35 foot long mold was 3D printed in sections, machined, and assembled at the Oak Ridge Manufacturing Demonstration Facility (MDF) before being shipped to AMG for hull production. By using the 0.30" (7.6 mm) nozzle on the BAAM and printing thinner extrusion beads than the typical 12 mm, they saved thousands of pounds of material. This mold was able to hold a vacuum without the need for additional surface coating. This project proved the feasibility of going direct to mold and skipping the production of a plug, thus saving months of time and thousands of dollars.

The jpegs give some of the story but the PDF gives the details of the 3D structures build, the finishing by a surface finishing multi axis surface milling machine and an example of its use as a mold. This is less about what a home builder can do (except on a small scale) but a clear indication of what could be organised for a complex mold shape of EG a cat hull bottom that may be used for a standard design.

Interesting stuff.

 

How about skipping the mold and just straight printing?

I could definitely see small beach cat and pontoon hulls being made this way.

I’ve been printing with PLA and it’s pretty tough, but nowadays they have all kinds of filaments.




And regarding the Hughes 26, that’s a good looking design with some similarities to my Seawing. There are quite a few Hughes designed boats being used here on Kauai by commercial operations that were clearly designed for their specific uses. Here’s an example of one. This thing just glides through swell.


Also if you’ve been following any of the social media posts from the Cannes Yachting Festival, there has been a good amount of chatter about the IC36 which was displayed and taking people for test sails. Featured here in earlier threads when it was still conceptual, the finished product looks impressive and fast!

 

The Siren 8.4 plans are available thanks to the kind work of Ray Kendrick from Teamscarab. The material list is up on Teamscarab web site showing the plywood version general details. There is also a mention of a foam glass version, but little detail in the materials list.

SolGato. Yes it is possible to directly 3D print a boat, but as process manufacturers have found out its cheaper to 3D print a mold then use that mold for fast production techniques of a product. EG painted metal roofing materials take 18 seconds from a flat sheet of metal to a painted ripple sheet of roofing material. 3D printing that would take minutes.

The IC 36 is a very interesting cat done by a guy who understands fast production cats. His Esscence 6 meter is a great looking and fast performing cat.

 

Right, om, just because you CAN 3s print a boat, doesn't make the materials ideal for boats. That said, there could be advancements in materials, but never gonna be able to print a long fiber.

 

This cat is a model of 3.5 x 2.16 foot over all with a 5.66 foot mast on the original version. The cat has a moveable 2 part wing mast which is radio controlled by servo’s as are the rudders. This sailing model can move very well when seen on a video and as the builder says that over the 4 boats he built during the design development he learnt a lot.

To quote the builder “This is a Wing Sail Catamaran project that I started over 6 years ago after seeing the new AC 45s introduced to the America's Cup races. The model uses 1.4 mm PVC sheet, Carbon Fiber tubing and 377 Dupont Mylar to "skin" the wings. The "Cookie Cutter" construction technique allows me to make quick inexpensive changes to the design without having to scrap a model and start over, everything is tweekable. Two Catamaran models are shown here, but I have created a total of four boats during design development, one of which only sailed once,and poorly. But that one sailing taught me alot, and I started another boat the next day. It's not all about finishing one boat, it's about developing a Platform that can evolve as you learn.”

The PDF’s contain the plans and cutting patterns. The wing ail plan contains a plan for a “reefable” wing sail which may not have been built. The plastic components can be cut out and bent if required with gentle heating of components to form EG the leading edge of the wing mast. Most components are glued together. The carbon fibre tubes are generally available through aircraft model stores etc.

You can learn a lot about the design and construction of a “dream” boat by modelling it. This guy has taken it to a high level and was starting to experiment with hydro foils etc. Interesting. The web address is RC Wing Sail Catamaran https://www.instructables.com/RC-Wing-Sail-Catamaran/

 

I own two 20+ year old HDPE boats and I think the material is perfectly ideal. They’ve been sitting in the Hawaiian sun for decades and have never needed painting, soft spot repairs, etc.. I pressure wash them one or twice a year and that’s it. If they had been printed and not molded, they would be even easier to recycle. Just ask our oceans how durable plastics are.

Yes 3D printing does take a while, but there are labor and production advantages. My printers work 24/7 without much complaint. And while plastic isn’t the ideal material for a lot of boat designs, for smaller stuff like beach cats and pontoon boats, and hull shapes that lend themselves well to the way a printer builds, it is a viable option IMO as access to large 3D printers become more available.

And there are advancements in materials all the time Fallguy. If you don’t use the technology or follow it closely and rely on an article here and there as a basis for what’s possible, you may miss the innovations that are taking place like CF3D -Continuous Fiber printing.

CF3D is being used for example with Carbon Fiber filament to create strong and light structures that require less reinforcement and lattice work by allowing overlap of continuous length material since it isn’t made up of fine particles suspended in filament like common printing material.

Anyway, I wouldn’t bet against 3D printing technology. It’s been adopted and used by so many industries for different uses like the hull mold manufacturing OM posted about, aerospace, rockets, etc.. and the innovations will only continue in the decades to come.

I’m still waiting for is the Star Trek style home 3D food printer replicator infomercial to appear on late night TV. Might be the only cooking device you’d need on a boat.

 

oh, I am not against it; just sayin it needs to be more than just plastic is all; think it is really cool

 

I am just finding this thread after a long absence from the forum. I just got back in touch with my sailing mojo, and will be retiring in 18 months or so.
A question on a harry proa and a foldable leeward ama.
Do you think a 3 piece ama could be made sufficiently strong and light to make a longer/larger trailerable proa?
It does not need to fold so much as plug together. That long leeward is the limiting factor for practical trailering.
I imagine the two mast folding design, then plug on the needed length for that leeward.

 

Skyking1. Try the following web page November Reports - 2001 https://www.duckworksmagazine.com/01/reports/2001/11/reports.htm
The jpegs will give the idea of Denny's Harrigarmi. It was a trailable 35 footer and I suspect if you ask you may still find a set of plans.
Next a Harryproa type build by a guy in NZ. This guy was inspired but did most of his own design work, its called Jacknife. Foldable for trailering with bow and stern that can fold as well. Page 67 of this thread shows Jacknife or it is the Harryproa site somewhere.
Some jpegs attached.

 

I often get confused with our society. Like the 4 people currently doing a world tour every 90 minutes for 3 days in the Dragon capsule in space. It only cost the guy $US200 million and is considered a “charity event” for tax purposes. Now I get to our power catamaran for fishing for 6 friends. The 39 foot centre console “fishing” cat in its original form had two 300 HP outboards on it. The cat could do 60 plus MPH. This didn’t satisfy several owners, as the best fishing spots may be fished out if they don’t get there first. So, they ordered the 39 foot cat with four 400 HP outboards on the stern. Result you can get to your favourite fishing spot at 95 MPH. PS. The 300 HP engine sell for about $US 35,000 and the 400 HP engine sell for about $US 44,000. A mere $176,000 in engines to do 95 MPH.

So why am I confused? The 600 HP version has a range of about 400 miles, the 1600 HP version has about 200 mile range. So, a day’s fishing can cost you $1,300 in fuel for 30 lbs of fish and this relaxing day can be over in 3 hours with your ankles and butt being pounded by minor seas as you get windburn at speed. Enough, just my personal view.

The cat itself is a well designed and built boat. The Compmillennia LIGHTSPEED Model 1188 catamaran is 39 x 12 foot (with two 300 HP engines) or 39 x 14 foot (with four 400 HP engines). The light weight is 8,500 lbs and the cat can carry 18 people (3200 lbs) with 425 gallons of fuel (3200 lbs). The motors weigh 1200 lbs for the 600 HP version and 2800 lbs for the 1600 HP version. The total displacement is about 18,000 lbs.

In spite of my opening comments, the 1188’s are very fuel efficient due to its light weight and its single-step hull design. In the stepped hull, a structural “notch” is positioned high enough on the either side of the hull to reach above the water line when the boat is cruising. Aft of the notch, the bottom of the hull is slightly higher than it is forward of the notch. The step creates a low-pressure area that sucks air under the boat through the side notches. With more of the hull lifted out of the water, the boat experiences less drag and greater efficiency — as much as 15% greater efficiency.

The hull laminate, a foam sandwich design using e-glass and aramid-reinforced vinylester. In general, the 1188 employs carbon fiber composites for their stiffness and light weight in the canopy and along load paths such as the forward and aft bulkheads, with e-glass and aramid fiber composites used everywhere else. The design keeps the laminate thin, typically one or two plies of biaxial, triaxial or quadraxial nonwoven fabrics and some unidirectionals and incorporates more laminate in areas needing protection against impact damage from debris in the water or docking, and to strengthen resting points when the boat is berthed on a lift. The primary glass reinforcement is Vectorply E-LT 3200 0/90 stitched biaxial fabric. For small parts and bonding tapes, the project uses Vectorply E-BXM 1708 and 2408 45/-45 double bias stitched fabric. The aramid reinforcement also comes from Vectorply, KDB 1308 45/-45 double bias stitched fabric. Carbon fiber-reinforced are from Zoltek unidirectional, woven and 45/-45 stitched products. Sandwich panels are constructed using several weights of Divinycell H or HM foam core. Higher densities are used in high-load areas such as the keel area and transom that the engines mount too.

To lighten the 1188’s structure, the cockpit is a more integral component of the vessel, borrowing design elements from large ocean-sailing racing catamarans. The hulls of sailing cats are joined by two transverse beams, with a “deck” created simply by stretching high-strength netting material from hull to hull. He replicated the aspects of this structure “by using the aft and forward bulkheads as the primary transverse structure, allowing the composite deck between to be quite light.” One jpeg shows you the carbon fibre strips on the under wing to strengthen it without excessive weight.

The initial boats were built in a plywood hull mold covered with high-pressure laminate as a mold finish. By the end of 2019, Compmillennia had built its ninth 1188 hull on these molds.

An interesting design well built. This is about the build not the function of the boat.

 

thanks Oldmulti. I had studied the jackknife proa, but had not seen "Harrygami". What I was spitballing was that folding piece on jackknife, but making them longer say 1.5 meters long on each end, and fasten them on rather than hinge.
That way you could have a 30' windward hull hinged to a 30' leeward, then plug on the 3 meters of extensions to get the proper ratio. Truly just spitballing the idea out there, and figured I had somehow stumbled on the proper thread for it
I don't know if you could make that joint both strong and light enough. The leeward does all the work on those harrys.
I am also with you on the twin engine power cat above. That is plenty fast.

 

Skyking1. At one point Rob Denny of Harryproa was doing a folding bow/stern version of I think a 50 footer, so that it could fit into a standard container. again search his web site especially the older stuff and see if you can find it. I think Rob had similar concerns but I do not know if it made it to a finished boat. Also Rob is approachable and will answer questions put to him about the plus or minus of some of his ideas. There have been many other boats that have had a lifting stern component (EG Firebird 26 foot cat) etc for a variety of reason. The most extreme is a 47 x 8 foot plywood monohull sailing cruising yacht called "Breakdown Schooner" by Phillip Bolger that could be broken into 3 pieces for transport. The boat got built. Jpeg of some plans below, detail in "Boats with an Open Mind" Bolger book.

 

Thank you oldmulti. I was looking at woods and wharram cat designs when I found the harryproas, which were quite intriguing. All my sailing was in keel boats so the performance of a multihull was very attractive.
My father and I built small boats for many years together, from sailing kayaks to a diesel trawler. I can't even think of the designer where he got the plans but they had been around a while in the 80's when he got the trawler plans. So much has changed along the way.

 

The following “Foil Ferry” is an indication of the future and has been given $400,000 of government funding to help it become a reality by Bieker design, Baird Marine and private backers. The intent is a zero-emissions high-speed waterborne transportation in Puget Sound. The design includes options of fully electric propulsion or diesel-electric propulsion for extended range. Owing to its extreme efficiency, the diesel-electric option is two to three times more fuel efficient than conventional fast ferries and has the potential to save 1,500 tons of CO2 emissions a year, while the fully electric version offers even greater improvements, according to the developers.

The Foil Ferry, the new catamaran vessel (more like a sea sled shape) would be fast and easy to construct. The vessel will be 98.4 x 23 foot with a 107,000 lbs displacement with the 150 and crew passengers on board. The non-foiling draught is 10 foot and a foiling draught of 5 foot. With 1,400 HP of installed power, the carbon-fibre-hull vessel will have a cruising speed of 35 knots.

The proposed engine options are two fully electric with a range of 25 miles at 35 knots. With two diesel electric engines (similar to Hybrid car engines) the range could be 215 miles at 35 knots. Remember this is a specific short run ferry. There can be rapid charge or EG battery swap at turn around docking points. The foil take off speed is 20 knots. The baseline propulsion system for the prototype ferry would be a pair of diesel engines driving propellers via bevel gearing in a Z-drive configuration.

Foilers do not operate with a large amount of hump drag and therefore they do not need a large amount of installed power to get over the hump. Once they get on foil, a well-designed foiler can burn as little as 50% of the fuel a catamaran burns. But the foiler has inherently low wake and is less affected by waves. The Bieker design claim advances in materials, controls, and propulsion. It also reaches back to an ancient planning hull design, a Seasled hull, which is just about perfect for a foiler like this.

The design is a carbon fibre PVC foam structure. Bieker experience in AC cats is directly transferable to this design. The vessel’s hull is constructed using room temperature-cured, resin-infused carbon fibre with foam cores above the waterline. This results in significant weight savings over the lightest aluminum construction. The struts and foils are constructed of high temperature-cured carbon fibre laminates, achieving the same strength and stiffness of high strength steel at 20 per cent of the weight. These advancements in foil design and manufacturing can be seen in the latest America’s Cup foiling yachts. This allows the foils to be thinner, stiffer and better profile than equivalent aluminum or stainless-steel structures. AC foilers run at 20 to 40 knots on sail power and Bieker design employed Tom Speer for his foil design skills that he applied in AC cats.

An interesting design that gives a hint of a more environmentally friendly future. Some jpegs of the proposed design.