Multihull Structure Thoughts

This is an update with a very interesting youtube video. Sometimes there is a design that capture the imagination of people due to the concept and visual image. The Evergreen 6 was one of these designs. Mike Schacht and Laurie McGowan conceived the cat for a Woodenboat design competition but final plans appeared not to be completed. A Swedish guy Michael Kerszemaker of Zandaam, NL contacted Mike and asked if he could build an Evergreen from the available limited line plans, Mike agreed. The Swedish guy was a good boat builder and applied his own improvements. Mike Schacht sent a very good jpeg of the finished boat on page 147 of this thread.

The Evergreen 6 is 19.6 x 11.3 foot with a built weight of less than 1680 lbs and has two 24 foot carbon fibre masts with two 140 square foot square topped mainsails. The design has low aspect ratio keels with a draft of 1.6 foot. The cat is trailable and can be folded or expanded on water from 8.2 to 11.3 foot. 2 folding methods were developed and tried. The original expansion methods was sliding cross beams in slots in hulls as per the original design drawings. But at a later point in the attached video you will see a Marple/Brown type swing cross arm arrangement that is very simple to fold and unfold. An excellent approach.

The Swedish builder was responsible for the structure and choose 6 mm plywood skins over plywood bulkheads with timber edge frames and western red cedar stringers. The external of the hull is covered by 250 gsm carbon fiber in epoxy.

The cat appears to sail well in light to moderate airs with the owner commenting “You made a great design, easily 11 knots with Beauford 3-4 aft windspeed. I’m so happy that everything did well today, a perfect day for testing the boat.”

There is a video available on the build, launch and sailing shoots of the Swedish Evergreen 6 is available from https://raidextreme.wixsite.com/raidextreme/news or from evergreen 6 expandable catamaran youtube - Google Search https://www.google.com/search?q=evergreen+6+expandable+catamaran+youtube&rlz=1C1GCEA_enAU752AU752&oq=evergreen+6+expandable+catamaran+youtube&aqs=chrome..69i57j0i546j0i30i546j0i546.26934j0j15&sourceid=chrome&ie=UTF-8#fpstate=ive&vld=cid:5483310a,vid:Nizzss-F2X8

Or search youtube for Evergreen 6 expandable catamaran. The video is 4 minutes long and very informative.

If you would like a larger 26 foot version of the Evergreen 6, Mike Schacht forwarded some information on page 196 and 197 of this thread.

The jpegs are of the design and build with original beams before the change to the cross beams.

PS Mike Schacht, if you are looking at this thread, did you have any input or comment about the second folding cross beam approach used by the Swedish builder? It looks simple and effective with a minimum of building effort.

 

The keel is so far back, I would expect some lee helm. Is that the intention, or have I overlooked something?

 

Mathieu Bonnier, founder of the Liteboat company is a solo rowing adventurer (Transatlantic race, North-West passage) and wanted a new project. The following trimaran was created to do the 2016 Race to Alaska without that you are required to complete the course without any assistance and with no motor. The tri started out as a Liteboat rowing shell (probably a Liteboat Duo) then had floats attached to form a trimaran. Sam Manuard was the architect for the design which was 19.6 x 9.2 foot and weighs 220 lbs empty. The carbon fibre mast carries a North Sails wardrobe composed of a 57 square foot mainsail and an 86 square foot gennaker. The other motive power is a pair of oars. For the 750 mile Race to Alaska, the available accommodation was a tent with a 2 foot wide base. You are either sailing, rowing or sleeping.

The tri is a full vacuum infused foam fiberglass structure with carbon fibre reinforcements and mast. The design was intended to reach 10 knots if conditions were appropriate. The boat sailed faster when all was working well but Mathieu is a novice sailor. Mathieu is an excellent seaman though. His description of rowing across the Atlantic was “boring”. Hmm. This tri required careful handling in stronger winds as the floats did not have a large amount of buoyancy.

This tri is a design for a good day sailor/rowing exercise machine, or if you have an exceptional tough seaman with sailing experience, longer term adventures. The jpegs give the idea.

 

I was looking at boats on the YachtSalvage web site and saw a 43' catamaran 1956 designed and built by 8 Engineers , if it is a 75 year old cat it looks good . I don't know how to post pic,s . While it might fit more into the golden oldies , if it is in fact a 1956 cat then I would be interested in both design and build / materials .

 

Robert. The sailing shoots of Evergreen in the youtube seem to indicate a well balanced boat even thought the keels are a far way aft. There are various small cats like the Dart 16 and 18 or Richard Woods Quattro 16 that have similar hull shapes and work quite well. Any comments from others.

 

Rberry. You have found one of the classic cats of all time, literally one of the first major cats that started the large catamaran revolution. I will do an item on it tomorrow. It is amazing that it is still surviving. Even moderately done plywood and timber can survive in pre epoxy saturation days.

 

Also used on this elegant concept for a small poly-esque style catamaran by the aforementioned Mike Schacht.
Proa File | Manu Kai: Hawaiian double canoe https://proafile.com/multihull-boats/article/manu-kai-hawaiian-double-canoe
The proafile site is well worth a look through if you like interesting boats.

 

Rberry asked about a 1956 cat that was available for sale and was there any history. The catamaran is called Dreamer and was designed by Hugo Myers with Bruce Ewing and built by these 2 plus 6 engineer friends over 1.5 years of weekend work. Dreamer is 43 x 18.2 foot weighing about 14,000 lbs (original designed to weigh 10,000 lbs). The original mast carried a main and jib of 800 square foot. An 800 square foot genoa was added to the sail area. The length to beam on the hulls is 16 to 1. The draft is 2 foot to 7.2 foot over the daggerboards. The underwing clearance is 1.8 foot. Power is a 50 HP outboard.

The reason this cat is significant as is it was one of Hugo Myers first designs, Hugo went on to design Seabird 44 foot ocean racing Transpac winning cat and many other models. Dreamer was the first symmetrical hull cat that was raced against the Choy designed 46 foot Aikane which had asymmetric hulls. Dreamer could outsail Aikane upwind and occasionally beat Aikane around a course. In 1956 Rudy Choy cats were the benchmark but here was a symmetrical hull cat beating them. Dreamer is an important historical cat.

How was dreamer built, with 12 mm plywood and timber. The majority of the shell is 12 mm plywood covered with fiberglass. The hulls are multichine (250 mm wide panels between chines) that were symmetrical side to side and had fine bows and full sterns. The stringers are 38 x 50 mm. The cross beams are 75 x 300 mm hollow box beams placed 6 foot apart in the original build. The current advertising claims the box beams are 100 x 225 mm. The daggerboards are solid Douglas fir.

If Dreamer has been well maintained it would be a good find that is suited to Californian waters. Hugo design was well done for the time, but the underwing clearance is low compared to modern times.

The jpegs give the idea of a historical cat. I have some other drawings of the cat which I will show when I find them. Later edit, Hugo Myers later famous design was Seabird, a 44 foot ocean racer. I have included a few jpegs.

 

Thank You oldmulti , what is impressive is she still lives on the water , a true testament to the designer and builder,s . It begs the question of how much more refinement engineering wise can you get from modern design even with the use of computers . So when the question comes up on old designs -v- new , I think material , method and means would be the primary things standing between new and old , the question of weather it is a well designed boat is another mater , new or old .

 

Rberry. Modern multihull owe a lot to the development and understanding of how to use materials. EG Epoxy, 9 mm plywood and fiberglass were around in 1956 but people did not have the experience to combine these materials together in 43 foot multihulls. Result Dreamer was built from 12 mm plywood 38 x 50 mm stringers etc, when 9 mm plywood, 22 x 38 mm stringers etc would have been sufficient. Result Dreamer is heavier than it needs to be. The design of Dreamer was in the right direction but if designed now would be 25 foot wide not 18.2 foot, have an underwing clearance of 2.8 foot not 1.8 foot and the hull length to beam would be about 12 to 1 not 16 to 1.

As designers developed structural and design understanding, cats have gotten stronger, wider and capable of handling bigger rigs. Unfortunately they have not often gotten lighter as modern sailors want airconditioning, freezers, big engines, electric winches, big water tanks or water makers, toys galore etc.

But if you are ruthless you can build a global racing 60 x 58 foot ocean racing tri that will displace fully loaded 14,000 lbs and carry a 2500 square foot upwind rig.

 

This is a relatively new design from Mike Waller of Waller yacht design. The Waller 1350 is a larger version of his full bridge deck cruising catamarans. The Waller 1350 is 44.25 x 24 foot with a weight 20,600 lbs and a maximum payload 8,800 lbs. The average payload expected is 3,800 lbs. The 59 foot aluminium mast and boom carries 1,232 square foot upwind and can carry options to increase the area. There is no self tacking jib. The hull length to beam is 10.8 to 1. The draft is 3.9 foot over the low aspect ratio keels ans underslung rudders. The underwing clearance is 3 foot. The power is intended to be inboard diesels.

Mike Waller wrote “The WALLER 1350 is a full bridge deck cat has been specifically designed as a live aboard, long distance cruising cat for a couple or a small family. The design features rounded bilge hulls, and mini keels for cruising simplicity and lower cost, with inboard diesel sail drive engines for safety, convenience and reliability. Extra care has been taken in the design process to make her look like a molded boat, even though she is intended for amateur construction. This is a go anywhere boat, and will make a safe and comfortable home for her owners no matter where they choose to travel.”

The accommodation is optimised for a cruising couple, and the starboard hull is dedicated to a huge owner suite, with double berth forward and W.C. aft. On the port side there is a double cabin forward with toilet, and a single cabin or laundry/workroom aft, with a large galley between. While galley down in arrangement, the galley has large ports and windows, and a clear opening to the main saloon. The main bridge deck saloon features a settee/dinette and a separate chart table area, as well as a large ice box against the main aft cabin bulkhead. Steering is from a raised helm platform under a raised cockpit roof for all weather sailing.

The construction of the Waller 1350 is basically a glass/timber or glass/foam boat, but unlike other designs, no one construction regime has been applied throughout. Instead, the best and most cost effective method has been chosen for each area of construction. The hulls and bridge deck are constructed with cedar timber-strip/fiberglass sandwich, and has both strength and cost advantages over foam cored structures. The bulkheads and cockpit area are mainly foam/glass panels, as these are ideal for large flat panel construction. Other dividers and panels, and parts of the turret, are in ply for simplicity and cost, and the interior joinery is in honeycomb or foam composite panels for ease of construction and finishing. It is a sensible approach using materials as appropriate for lightness and strength. Any boat over 40 foot is a very large undertaking and if you can buy prefabricated foam glass or honeycomb panels, it can speed up building.

Mike Waller larger cats generally sail and handle well but they are cruiser occasional racers. This cat will perform well and should be capable of 8 to 10 knot averages if well built.

The limited jpegs give the idea of the cat.

 

Orphie boats decided to a more environmental friendly boat for charter work and for personal use if others wished to buy it. They started with a blank sheet of paper and conceived an electric powered trimaran that could have a kite sail for assistance. Jean Marc Piaton and Clément Bercault, naval architects, designed the Orphie 29' (also known as the Garfish 29). The trimaran is 29 x 17.4 foot wide and weighs 4,150 lbs including the electric 50 kW Torqeedo outboard. The mainhull has a length to beam of 6 to 1 and the floats have a length to beam of 11.5 to 1. The draft is 1.2 foot over the hull and 2.3 foot over the outboard leg.

The power options can range from 12 to 24 kW and 25 to 50 kW engines, 30 to 60 kWh batteries, 400 W solar panels and for the sailors a 215 square foot kite wing for sailing. The batteries are from a BMW i3 car. If the 50 KW engine is chosen with a single BMW i3 battery the tri has a 35 mile range (about 55 klm) at 8 knots. Peak speed with a much reduced range is 15 knots.

The construction of the tri is mainly plywood and timber, epoxy saturated and glass cloth covered, with carbon fibre cross beams. The wing decks are canvas. The 60 kg carbon T-top is an option where solar panels are fixed.

The accommodation is designed for day charters and recreational fun. The large open cockpit and wing decks are designed for a maximum of 10 people. There is a small cabin forward for some food preparation, a toilet under a seat and a forward bunk. This is a day cruiser not a weekender.

The kite sail is an interesting addition that will boost range and increase speed in appropriate conditions. But don’t be tempted to use it downwind for half a day and then work out you don’t have enough battery power to get home upwind. PS Kites are a lot more work than they look as you need to keep them under constant attention to keep them flying well.

The jpegs give the idea of a very creative design. But as per usual I have range anxiety, 35 miles between power points is a very slow way to get anywhere unless fishing and sun bathing is your game.

 

Adagio is one of the most famous racing trimarans of all time. It was designed and built in 1969 by the Gougeon brothers and has won races ever since, or should we say the mainhull has been winning races ever since, because according to Meade Gougeon son “Today, not much of his father’s tinkering remains. Most of the original tiller is there, but everything’s been pretty much replaced on the boat, except the main center hull.” This leads to the point of this post. I am told that “that timber boat over there is 100 years old”. My question is what parts of it are 100 years old? All plywood and timber boats require maintenance even when they have epoxy saturation and glass coverings.

Adagio is 35 x 24 foot weighing 2,600 lbs with 640 square foot of sail. There were several versions of the 40 foot high wing mast from a full bent plywood 450 mm long cord version to the latest 300 mm long cord Stressform wing mast. The Stressform wing mast had several layers of 5 oz carbon fibre, 2.5 mm Douglas fir layup for the wing sides with several layers of 100 mm wide 9 oz carbon fibre unidirectional tapes wrapped around a 75 mm PVC mold tube as the forward edge of the wing mast instead of a solid wood leading edge (last jpeg gives the idea). (Stressform details on page 5 of this tread). The main hull and floats were 6 mm 3 ply Okume tortured ply. The main hull had 12 x 19 mm ribs every 100 mm from bow to the main beam then 19 x 19 mm ribs every 300 mm from the main beam aft. Float gunnel was 2 layers of 22 x 45 mm. The ply float deck had deck beams every 300 mm. The float deck also had 2 deck stringers of 19 x 37 mm. The cross beams were timber with wire water stays. This boat had relatively small floats but adequate for the displacement. You don’t need carbon foam to create a simple light and very fast boat. And yes, there is not much real accommodation.

In 2015 Matt Scharl with Meade and Gougeon Brothers’ president and CEO, Alan Gurski, assessing Adagio’s winter worklist. Meade’s concern was a 3-foot section of track that kept separating from the mast. Late at night Scharl can’t “popping a few screws,” and extracted the entire track. This was the start of a transformation for Adagio. Over 50 years of racing this unique and experimental trimaran had amassed many trophies but with Meade’s health declining, he had handed the responsibility to son Ben and Gurski, to ensure that the boat remained competitive. By the second season, they had a long-term vision of what its restoration would look like over the next 10 years, being realistic about what was most important—and having the budget to do it right. “EG, a few years ago, a crack developed in the centerboard trunk, and every time we went over a wave, the boat would fill up with water,” Gurski says. “That winter’s job was to tear the boat in half, tear out the centerboard trunk, and then put it back in. That wasn’t fun.”

It was Meade who eventually enlisted Scharl to assist his son and Gurski himself with updating and racing the boat. What I realized right away was that her sails were unforgiving, the lead positions were not optimal, and the hardware was aging on the boat.” “Over the years, Meade would try stuff, put it on the boat, but then never take it off if it didn’t work. There was a lot of unnecessary stuff on the boat,” Scharl says. “So, the primary thing was to simplify it and get a good set of modern sails. It was about making the boat easier to sail. It weighs only 2,600 pounds to begin with, so there wasn’t much room to take much weight out.” Roughly 300 hours of labour went into the boat in the first year, 200 the next, and by the third, the work list was much smaller. That was when they finally added a traveller. “We had to do quite a bit of reinforcing to support the traveller on the transom,” Gougeon says “It has made a huge difference on the boat”.

Adagio’s sail number is E5, Gurski explains. The E stands for experiment: “Adagio is Meade’s fifth experiment in boat design and construction, so I like to say there were four failures before it. It took until 1969 to get to Meade’s E5. And it just so happens that Adagio, for what she’s built do to—which is light-air sailing in the Great Lakes—holds true. She’s a light-air machine, and when it’s 8 to 10 knots, any boat in any fleet can’t hold up to her. We could make her stronger, sure, but we’d be hard-pressed to build her stronger at the same weight, or lighter. He got it right, so why change a good thing?”

Gougeon says his father “Was all for making changes for a tenth more speed and open to any changes that might allow for that. He would try to reduce the weight to make something work better, pushing it lighter and lighter until it broke, and then he’d go back to that point so it didn’t break again.” Scharl says Adagio is now close to perfect. “It’s crazy how fast the boat is,” he says, “but the number one thing is how quiet it is. Up to 18 knots downwind, it’s absolutely quiet.’ What Adagio does in all conditions is incredible. In winds less than 10 knots, no one is touching that boat. In the right conditions, Adagio would beat every boat by 15 miles—I guarantee that. It destroys TP52s and Great Lakes 70s because it’s incredibly slippery.” Scharl’s boasts, of course, are backed by results, including a multihull division win in the 2020 Port Huron to Mackinac Race, a brutal upwind slog that saw most of its competitors retire. The previous year, the team of Scharl, Gurski and Gougeon finished second—by 14 seconds—to the 60-foot trimaran Earth Voyager. In 2016, 2017 and 2018 Adagio took home first-place honors.

Adagio’s results reflect its proof of design, and its construction technique as well, but remember the words of what E 5 (Adagio) was an experimental boat. The majority of the boat was built light until it broke then it was rebuilt slightly heavier. As things broke they were repaired or replaced as is indicated by the replaced centreboard case. Remember the words of the son “Today, not much of his father’s tinkering remains. Most of the original tiller is there, but everything’s been pretty much replaced on the boat, except the main center hull.”. The joy is you can rebuild timber ply boats, the downside is even with good construction you have to occasionally rebuild parts of timber ply boats.

This is a brilliant tri that changed to course of multihulls. The jpegs give the idea.

 

Regarding the Orphie 29 above, not to pick on it, but being that this is a design forum I have to question the practicality of an electric Trimaran of this size for day cruising versus and in comparison to a Catamaran design.

I would think a Catamaran of the same length and beam would provide more efficiency, more functional deck space, the same amount of lounging space by way of a forward tramp, and would be a better platform to integrate a large solar hardtop that could actually generate and offset some motor power use.

Also with the speeds and range stated, I think a Cat could make use of smaller more efficient motors allowing for a smaller battery bank and reduced overall displacement.

Some years ago I thought a lot about converting a Corsair Sprint that was rig-less and for sale into a Solar Electric Trimaran, and decided I would need to use the wingnet space for solar so it could still be trailerable. My plan would have had the solar mounted on bi-folding tracks that would allow them to fold and span out over the nets for max solar harnessing, but with Farrier boats being sporty and low to the water making them more susceptible to damage, and not wanting to block the use of the tramps when at rest (a perfect time to recover power via solar), I decided having the panels up high and having them double as a shade structure was best option on a slow speed day cruiser, and all this pointed back to a Catamaran design which I feel also handles chop and points better in wind and ocean swell, again resulting in better efficiency.

There are a number of small solar electric catamarans of similar size that offer more bang for the buck IMO, and are more practical from a charging/recharging day use slow speed cruising perspective in that they are able to offset consumption with large solar systems that have been well matched to the motor and battery bank size allowing for more autonomy, and they offer the same creature comforts although some may not look as yacht-like.

The go fast big battery big motor planing boats that only run for an hour don’t make any sense to me at all. The integration of foils is helping to make some of those designs more practical, but I’m more interested in slow speed semi-planing cruising autonomous cruising designs, and I think one could argue the Cat is in a lot of ways a better platform for this kind of application and use, unless foldability and trailering is a necessity.

Anyway, just my thoughts

 

SolGato. Tomorrow I will feature probably the most efficient electric power boat I know. It will be featured partially about its electrics but more about its structure which amazed me. Yes, a very well designed and built slower running cruising cat or tri can achieve reasonable ranges but the key components are weight, battery capacity and solar panel area. The number of hulls is secondary as long as they are designed for the task and that generally means relatively thin round bilge shapes and a low windage design above the waterline.

Most 'commercial' designs are designed to sell the comfort side first then think about how they will be powered second.

Edit, if you need to understand how rapidly electic power is developing look at EV's. Tesla model 3 long range can go 500 km plus on a 100 KW battery. Mercedes-Benz unveiled the high-performance Vision EQXX that has over 1000 km range with a 100 kw battery. Mercedes has a better battery and engine management system, lighter weight and better aerodynamics. The same can be done in boats with the right vision.