Multihull Structure Thoughts

I have always thought there is an essential 'rightness' about the Tiki 21 and it certainly marked an aesthetic return to form after the rather awkward (to my eye) Pahis. Is this where Hanneke Boon started to have real influence on the designs? I am really looking forward to seeing what direction she takes the boats in next, if that is what she wants to do.

 

This is a very short one about “Aye Aye” which is a one off home build pacific proa with a crab claw rig designed and built by Jim Morris of Queensland Australia. Aye Aye is 32.9 x 16.5 foot. The mast is an aluminium 26 foot high and carries a crabclaw sail of 194 square foot area. There are no “formal” rudders, but is steered like a sailboard (mast rake, etc). Easily dismantled for transport.

Aye Aye was built in 2009/10 and sailed for a year before being sold. The construction is stitch and glue plywood/epoxy/fiberglass of the chine based hulls. The timber cross beams can be dismounted to allow the proa to be transported if required.

The accommodation is one double berth bunk and a space for a porta potti and small food preparation space.

No performance is mentioned but the highly rockered hulls would be required to help the “steering” by EG weight shift and mast shift with sail manipulation. This proa would teach you more about sailing and boat control in a day than you would learn in a year with a boat with a more conventional rig and rudder.

Unfortunately, life got in the way and Jim had to sell the proa after a year due to his commitments to his wife and family. Interesting proa. Any further information would be appreciated.

 

Clarkey. Yes, Hanneke influence has significantly increased over time to the point that James was more a figure head. The progressive development of chine hulls with fuller ends, the rig development with wing sail mains, the continuation of the Tiki range and limiting development of Phai range etc gives a hint of the direction. The Mana 24 foot design is the future but the real issue is the Wharram marketing organization versus what Hanneke would like to really design. Wharram "designs" is where the money is, not a second version of EG a Woods design, so Hanneke needs to continue to pay homage to the original concept. Also Hanneke is getting older (about 70) with her own health issues. I hope she continues to do innovative designs but I think being the face and running of the Wharram empire may limit her future designing. I really hope I am wrong.

 

All good points. I see that the Pjoa enterprise in Poland has just launched their first catamaran 'Pjoa 600' which seems to offer similar characteristics to the Tiki 21 but with a slightly different slant, being evolved from a proa background rather than double canoes.

 

Wade Tarzia decided he wanted to experiment with a few ideas to create a proa. The idea was to produce a cheap prototype of the idea to verify his ideas for a bigger proa. So, Wade partially “designed” then developed a proa from materials obtained at the local hardware store. “Short Dragon” is 16 x 7 foot with a weight of 280 lbs fully rigged. Now we start to have a small development situation. The initial proa was paddle powered and could go either direction. When the rig was obtained the proa became a tacking proa, as the sails were from The Wooden Boat Store; the main from a Shellback Dinghy and the mizzen from The Nutshell Pram (54 and 37 square feet respectively). The initial rudder system was a each cross beam with a kickup rudder depending on the direction of sail. After initial sailing a single rudder was put on the stern of the main hull. The main hull is 2 foot wide at the gunnel, 1.2 foot wide on the bottom and 1.9 foot high. The hull bottom has a 0.33 foot rocker. The float hull is 14 foot long and has a beam of 1.2 foot and a depth of 1.2 foot in a V shape. The displacement of the float is 270 lbs.

As you can see from the dimensions the “design” was intended to be a simple shape from 2 lengths of 8 x 4 foot sheets of plywood scaphed together then cut in half to form a main hull side etc. Simple.

Now the resulting sailing proa performed reasonably well. To quote Wade “In 5-10 knots of wind the proa will cruise along at 5 to 7 knots. I have often hit 10 knots, sometimes 12 knots, and in one blaze of glory hit 14 knots, although we were probably "pushing the envelope". In medium air it will provide some fun, in light air it can take a passenger, but I recommend it as a solo boat. The lugsail is not the best choice for going close to windward, nor is a cat-ketch rig the best for windward work. I get about 55 degrees to windward course-made-good at respectable speed, which is not unusual for a low-tech cat-ketch rig. The boat will of course point higher, but speed will drop drastically. Pinching up as high as possible will drop speed to about 3 knots (depending on the sea state). Could I improve mediocre windward performance with increased skills? Maybe. Suffice to know that an outrigger canoe is sometimes better at going very fast at lower windward courses rather than pinching up to go slowly at higher windward courses. When this is not true, you are heading for rocks and need to sail as high as possible at whatever speed. Doing 6 or 7 or 8 knots at 55-60 degrees is much more fun than pinching up at 3 or 4....if no horrific obstacles threaten.”

Now the construction. As I said local hardware store stuff which means: 6 mm cheap CDX plywood for hulls, common pine for stringers, laminated pine shelving/desktop materials for boards, oak and Douglas fir for load-bearing struts, Douglas fir flooring planks laminated for akas/cross-beams, 6 oz. glass cloth, System Three epoxy, a few bronze ringnails, some stainless steel hardware, a few commercial blocks and cam-cleats, and low-stretch synthetic line for halyards, sheets, and downhauls. Install (epoxy) the gunwales, stringers and chine logs, all 25 x 50 mm. The chine logs should be slightly below the bottom edge of the plywood to all shaping before the attachment of the bottom panel in the main hull. Wire the topsides together at the bows and spread the topsides out using sticks that approximate your estimated beam at the top center of the hull and the bottom center of the hull. Make sure you give yourself plenty of time to eyeball the hull to make sure it is the shape that you want. Install any bulkheads and frames to hold the shape. After the bulkheads are bog, glassed in then turn over the hull and fit the 6 mm bottom panel. Glass over the entire external of the hull with 200 gsm glass cloth and epoxy. An additional layer of 200 gsm is put over the bottom panel and at either end a small oak skid is placed externally on the bottom for beaching. Next install a 100 mm deep mast step on the bottom and a mast support panel at the gunnel line for the masts.

The 14 foot floats are again 6 mm plywood hull sides and deck. The hull side shape is cut out, gunnels glued in and the panels are wired together at the keel line. The bows are wired together and bulkhead panels force the hull into the V shape. Bog is then poured down the keel line. The 35 x 35 mm cross arm support struts are installed. After epoxying the inside of the float, a deck is installed. Also added was a heavy 17 oz glass tape to the bottom of the ama for abrasion resistance. The cross arms are laminated from 4 strips of DF tongue-and-groove flooring planks (tongues & grooves adzed down), tapering to three strips toward ama-end. Weight about 15 pounds each. The cross arms are rope tied to the mainhull and float struts. A lot of finishing detail was done prior to sailing.

After his trialling of the proa he decided this as no longer a “prototype” but was the boat for him and developed it further. With a dream to enter the Everglades Challenge, Wade converted his tacking proa into a trimaran with new cross beams and floats but maintained the same rig and main hull. He is really having fun.

The jpegs give the idea with the last 3 jpegs being of the “tri”. A good learning and development process that shows a “cheap” boat, if well built, can work well and be a lot of fun. PS this design concept could be built lighter with EG good 4 mm ply, 25 x 25 mm stringers and less glass. But also you would need to be more careful in its use.

 

Oldmulti do you know who would likely take over from Hanneke if at all, as in no figurehead making new designs after she is gone and just old ones sold.

 

Kdifzero. I do not know the "next" person in the Wharram organization. I do know the business has several other people in it to handle EG the web design work, another to do marketing and processing sales of plans and materials etc. I am aware there have been people who have supported Hanneke in design work over time but I do not know if it is a real support role or a person in a training role. EG many years ago Richard Woods worked with Wharram. If anyone knows the current situation could you please advise.

I hope its not like Malcolm Tennant Design. After Malcolm passed the business continued for several years with the second in command but eventually disappeared even though the designs were very good. Once the original founder departs, often the business does not have an enthusiastic name and marketing face to continue the business. Its like the guy who took over the Norm Cross plan business, he appears to have lost interest.

It is part of the reason for me doing this blog, older designs are often good but people "hold the design rights" then do nothing with them because they get asked build questions, but lack the knowledge to answer the questions. I wish they would just release the plans and lets a community group who have knowledge of the design or building help each other. The Farrier builders really help each other with all sorts of build and operational issues.

The jpeg may repeat, may be the Wharram team in 2012. I cannot remember where the jpeg came from. If anyone can help?

 

Wade Tarzia had some success with his “trimaran version” of his 16 foot tacking proa in 2010 to 2013. He decided to build a new trimaran in 2015/16 as the he said the original was to strong and heavy. Wade went through several design iterations from basic drawings to a computer generated hull shapes to come to an idea of what he wanted to build. Although there was a thought of 20 foot, practicality again dictated 16 foot would be the length of the main hull. The hull bottom shape in the computer generated plans was round bilge with a transom. Now I am confused. In 2 jpegs there is a transom hull shape and in 2 jpegs there is a canoe stern hull shape for the main hull.

To give an example of Wade thinking “The cockpit of the main hull must accommodate the ama (outrigger float) and akas (crossbeams), leeboard, and the sail on its spars (right now planned to be a 113 square foot lug and 10 square foot mizzen). Given the need for permanent stiffening bulkheads (which intuitively I thought should have no more than 10 feet of separation), that would limit the ama to 9 or 10 feet (also to be a glassed foam construction). For the EC, of course two inflatable 16 foot amas used during the 2011 Everglades Challenge are an option.” Also “Much must be planned: length (16 feet), width (19 inches amidships), depth (15 inches for the wooden hull, and some inches of shaped and fiberglassed closed-cell foam on the bottom: this provides efficient bottom shape and also flotation to permit a self-bailing cockpit). The basic hull is done (~16 feet long, 15 inches deep amidships, 22 inches wide at top, 20 inches wide near waterline). I have just cut the sheer web with the rocker curve in it, and must now glue on the foam slabs, glue the unit to the plywood bottom, shape the foam, and glass the entire hull over on the outside (multiple layers over the foam).” Next “Short Dragon's cat-yawl set-up could transfer right over (though would also carry over shrouds and forestay, which I may not be happy about). I also have a 113 square foot balanced lug -- a bit big maybe -- I could have a ~85 foot one built (we do get a lot of light air in New England). I gave away Short Dragon's old 56 square foot standing lug mainsail (in thanks to the man who loaned me his Puddle Duck boat for the 2014 Texas 200 -- check out my write-up about this trip in Duckworks Magazine on-line; it should be out in Fall 2015) but I could buy another one, and it might be enough for this lighter boat along with the 20 sf marconi mizzen”.

The construction of the main hull is usual Wade, He is an inventive guy and decided to do a ply “box” shape with a vertical ply keel web. Then foam blocks are glued to the bottom of the hull. The foam blocks are “shaped” to the round bilge shape and then are glassed over. The floats for the 2010 tri were inflated tubes and he was thinking of continue using that approach but was thinking about a foam tube wrapped in light glass. He then started to think about folding cross beams but he rethought the cross beams and folding system. He thinks he will spring for T6 aluminium tubes (Dwyer Mast Co.), 2.5 inch diameter for the hull-mounted ones, about 3.5 feet long, and 5 foot long 2.25 inch tubes for the cross-beams. These can then telescope inside the hull-mounted tubes to produce a compressed width of 5 feet, which he thinks is acceptable for car-topping on a rack as long as the boat is light enough for that. That width makes better sense for trailering, too.

The jpegs are of a 2016 update. First are the “idea hull shape” but the next are the variations of the build. No reports if the trimaran was finished.

 

A Google reverse image search points to this post from 2012 on Cruisers Forum:

Comments on Gaff Rigged Schooner Cat - Page 4 - Cruisers & Sailing Forums https://www.cruisersforum.com/forums/f48/comments-on-gaff-rigged-schooner-cat-73973-4.html#post851132

 

Designer Colin Ayres (he also is a physicist) has done many multihulls with many going into “production” (IMP range of cats) in Western Australia. There is no indication who this design was done for, but it is the largest design of his I know. It is described as “Catamaran Trimaran luxury super yacht shell ready to finish” (available at $100,000 Australian). The vessel is 65.6 x 29.1 foot. The floats are 49 x 3.1 foot. Weight and displacement are unknown (guess about 45,000 lbs). The sale information says there are 2 carbon fibre masts available for $10,000 extra. No details of the sail plan. The length to beam main hull 12.6 to 1. Float length to beam 15.5 to 1. The hull draft is 2.3 foot. The proposed engine is a 120 HP Perkins (available as part of the purchase) in the main hull.

The accommodation can be anything you want but the initial concept is for a fit out for up to 12 berths with a large saloon and cockpit. Part of the initial layout can be seen in the jpegs. The shell is capable of having a flying bridge if wanted.

The build is kevlar foam fiberglass. Colin understands how to design multihull structures and if the boat has been built to the design it will meet any sea requirements. The interior is being finished in plywood with timber supporting structure. A tri like this will consume a very large amount of materials on the interior so it needs to be light and well done to get the best result. You may get a large vessel shell cheaply but the work to finalise it will be substaintial.

The sales stuff says this vessel can be an “all electric” with solar arrays, batteries and electric engines etc. Again, understand this is not going to be easy or cheap in this size of vessel. A 120 HP Perkins would be far easier and cheaper.

The jpegs give the idea of an interesting motor sailor design concept. Sorry about the limited jpegs.

 

Being from WA I’m familiar with Colin Ayres work and Imp Catamarans. I wrote a long post about it and then thought better of it.

 

Life is loaded with dreams, great graphics and a few people who will pay the money to convert some of these dreams into reality. This dream used the term “trimaran” and “sailing yacht” so I investigated. What I found was “a sailing yacht that can transform into a plane thanks to its four mobile masts. The sails are retracted and the four masts are lowered to become wings.” OK.

The “Seaplane-convertible sailing yacht 8P-sail-4M” is in trimaran mode 151.3 x 88.5 foot with four 131 foot high masts that carries 1400 square foot of sails and mast area. In plane mode the Seaplane-convertible sailing yacht 8P-sail-4M is 151.3 x 296.5 foot powered by four 5400 HP engines that can drive the plane version at 390 kmh.

This model will be manufactured at the Aerocoché plant and is designed by Yelken Octuri. It was designed for the princes Aziz, Dawood & Hashim, corporate executives of the “Masqat Airways” air transport company, and allows them to enjoy sailing along the Omani coastline with its 600-km range in the plane version. The propulsion is provided by engines in plane mode or the sails of the four masts in Boat mode. The surface of the sails is 1,302 sq. m. Each mast can be individually oriented through a double-jack system that ensures an optimal positioning regardless of the wind direction. In order to transform into wings, the masts must be lowered in horizontal position. The sails will then go to storage compartments located inside each mast. The four masts are lifted and lowered by a set of four shrouds set up on two central masts.

The accommodation includes sleeping cabins, saloon, galley etc and an external rear cockpit for lounging around.

The jpegs can tell you more than my words. I hope it will be built for pure interest, this is not something I would like to sail but going upwind at 390 kmh could be fun.

 

Mike Schacht is a creative graphic designer who also can design some very good boat concepts. Think of the biplane sailing catamaran called Evergreen an excellent 19.5 foot camp cruiser, he did with Laurie McGown. Mike has now done another biplane catamaran that has more cruising accommodation that is 26 foot long. From here on we are dealing with limited information and educated guesses.

The biplane lug rigged cat is in the “concept” phase and not much information has been released. The cat is 26 foot long with about 14 foot beam. The displacement is unknown. The free standing masts are 25 foot above deck level and each mast carries a 230 square foot lug sail with Miss Cindy type roller reefing (an excellent option). Lug sails are powerful reaching and running sails that if the lug sails are well cut, can get within 45 degrees up wind. Lug rigs are at their best from 55 degrees to running. The alternative could be a junk rig but your windward performance may be less unless there is some camber cut into the junk sails. The draft is 2.1 foot over the low aspect ratio keels and stern hung skeg rudders. The rudders are partially balanced by having some area underwater ahead of top of the blade.

The accommodation is claimed to be about the same as a Tiki 30. That means 4 single berths with space for a small galley and portapotti. Seats are on the ends of the berth. Headroom will be about 5 foot. Deck space is large, in an open wingdeck design. The intention appears to have a large sun shelter over the majority of the cockpit. For its size, this cat will be a very good minimal cruiser.

The construction appears to be chine plywood or flat panel foam glass, but that is a guess. The cross beams appear to be box structures and I think the cat could be disassembled for transport.

If Mike Schacht is willing to provide further information it would be really appreciated.

The limited jpegs give the idea. This is an excellent concept in a size many people want. It would be a capable small cruiser that would be affordable and is a size that will not take years to build. Well done Mike. The last jpeg is of Evergreen the 19.5 foot camp cruiser.

 

This enlarged EVERGREEN is inspired by DRAGON WINGS, the 30’ biplane Chinese junk catamaran design of Gary Lepak. Dragon Wings https://www.duckworksmagazine.com/04/s/vintage/multihulls/index.htm

I first saw this boat at Shilshole in the early 0’s and I hated it. Not the sleek, shiny and fast thing I thought a multihull should be (the gray porch paint topsides didn’t help). However I suppose age brings a new appreciation (along with the bad back), and I now recognize the boat to be an excellent job of industrial design, space planning, and dogged clarity of purpose over fashion. Being a designer, I am of course a slave to fashion so I doubly admire those who are not, but still get it done with style.

DRAGON WINGS checks all the right boxes: simple, efficient, plywood, no bridgedeck cabin, biplane rig, demountable. My takeaway was simply to shrink her down to 8 meters and provide some ‘downeast’ styling. I spent some time figuring out some good deck storage. You’ll note that my take has a reverse, or axe, bow. As I said, a slave to fashion. Well anyway, I got crossed up in details and imaginary customers and when the price of plywood doubled overnight, I just sort of hung it up to dry and never went back.

If I were to do it again, I think I’d opt out of the junk rig and just go for a nice, fully battened square top main. You’d get to windward a hell of a lot better. But horses for courses. I have some higher res images to contribute, and let me know if you have any further questions, happy to answer.

 

Re. the 150' x 88' trimaran/seaplane featured above:

Will there be a plywood version for home builders?