James Wharram (aka Jim and Jimmy to his friends) is also sometimes described as the father of the modern multihull but that is not entirely accurate because as we are seeing the World was full of people developing mould breaking revolutionary multihulls and very few of them owed anything at all to Wharram's designs which were always different from the mainstream. 
Indeed I would go so far as to say that the commercially successful multihulls that are so dominant in the World today follow totally different design principles and styles to the Wharram designs which even today are unique albeit that Wharram claimed the distinction of selling more catamaran plans for home construction (over ten thousand) and he and his wives Ruth and Hanneke built a terrific brand with almost cult like success by being very different and always seeking to be controversial. Some say that Wharram sold more than designs and his buyers instead bought into an entire philosophy. 
Today Hanneke runs the business with their son Jaime, but such is the way the boating market has changed since the Wharram heydays of the 60's and 70's the market for self-build has declined. A choice to buy Wharram plans to build your boat is now more than ever a lifestyle choice based on sustainability and beliefs. Keen racers and those looking for high performance sailing will not choose a Wharram design, and it must be said that sophistication, and luxury do not apply to Wharram designs either.  
The first Wharram design was the 24-foot Tangaroa on which the three adventurers Jim, Ruth and Jutta sailed to the West Indies. Flat bottomed with a tiny rig and cabins like rabbit hutches and their voyage must rank as one of the bravest in the history of modern boating. 
Living on a raft in Trinidad where Jutta had his baby, Wharram’s next design was the 40-foot Rongo. This brilliant design  is without doubt the basis for every Wharram since and if you look at her and the Tiki 34 and 46 the family likeliness shines out although the construction methods are now more modern ply epoxy glass sandwich and the build method evolved to be suitable for home builders but so much more sophisticated and nuanced than the designs that Wharram marketed in the 60's. 
After a tough voyage from New York to Ireland in 1959 Rongo was readied for around the world voyage. Jame had married Jutta, and they all set out around the World.  Jutta’s death by suicide in Las Palmas ended the voyage and Ruth and James crossed the Atlantic to Trinidad before sailing back to Ireland and then Wales in 1962. They had now sailed Rongo three times across the Atlantic covering over 12000 miles in her. 
After his abandoned World voyage James and Ruth lived with James' son on Rongo on a beach in North Wales. It must have been a very hard life indeed in a spartan plywood catamaran without any modern facilities, and I have no idea how they earned a living either. 
In 1966 James built a trimaran called "Tiki Roa" and took it to enter the 1966 Round Britain Race. Writing to AYRS and Multihull International, his ambitions for the double outrigger were frankly delusional. Its small sprit sail rig and V shaped hulls meant it was not going to succeed as a racer, and it had almost no accommodation either.  Post race James abandoned the concept and indeed became very much against double outrigger trimarans as designed by Kelsall, Crowther and Newick in particular.
At about the same time he designed a 22-foot catamaran called Hina and a 34-footer called Tangaroa. Both were very crude designs with spritsail rigs that were not a concept that could achieve the high performance sought by most multihull designers. He followed this with the 46-foot Oro and published articles in yachting magazines and his self-build design catalogue started to achieve sales and boats were built, and others sailed the Oceans in them. 
The building of a 52-foot Tehini in 1968 to 1969 took a lot of people's imagination. The film of this made by Ruth Wharram is now available on You Tube. Establishing a commune like existence of men and women around him was an alternative lifestyle which is now branded as being a hippy one and certainly the image of Wharram catamarans was one of hippy boats. Wharram wrote a lot about his view that the modern consumer society was doomed in the 70's. His philosophy of escape to live on sea communities fitted into the whole self-sufficiency movement of the 70's and Wharram was still preaching it and the pleasures of multiple relationships, sexual freedom and naturism into the 21st century.
Between the 70's and 80's the Pahi range was evolved too with hull shapes chosen to resemble genuine Polynesian concepts something they took further in the voyaging canoes they built for the 2008 Lapita voyage which was the antithesis of Heyerdahl's Kon Tiki expedition and proved the viability of double canoes with hulls based on examples of native canoes with traditional Polynesian style sails migrating East to West to Polynesia. 
In the 1990's Wharram and his wives (he always lived polygamously although married first to Jutta, then Ruth and lastly after Ruth passed away to Hanneke) sailed around the World in the 63 foot Spirit of Gaia although they were rebuffed when they attended a Polynesian voyaging rally where the Polynesian did not appreciate the English cultural appropriation of their traditions by a white Englishman.  Wharram lived his entire life fighting the "establishment" on behalf of ancient Polynesian concepts and to suffer discriminatory exclusion by those same people must have been an awful experience for such an enlightened man.  
Studying the journals of the AYRS, the pages of the UK's Multihull magazines and later the popular yachting press which finally started to appreciate Wharram in the 70's he shines out as a very opinionated character who seemed to be determined to pitch himself against convention at every level in his designs, his personal life and his confrontational approach. 
While the UK yachting community bought the grp catamarans from Bill O'Brian, Prouts and Sailcraft with their comfortable bridge deck cabins, Bermudan rigs, keels and centreboards and the trimarans of Piver, Kelsall and Crowther, Wharram railed against these concepts arguing the superiority of his plywood V shaped hulls, open slatted decks and lack of any protruding boards or keels. When he could not claim superior seaworthiness, he could say his designs were cheap and easy to build and he promised ordinary people the ability to build boats and live a fantasy-like lifestyle as "sea people".  
The books "Two Girls, Two Catamarans, in 1969 and "People of The Sea" in 2020 tell the story but as often with autobiographical writing I am left wanting to know so much more. 
In the late 70's there was a series of capsizes involving trimarans which following the success' of Kelsall, Crowther, Newick, Shuttleworth and Andrew Simpson were riding high. Tabarly, Tom Follet, Walter Greene, Phil Weld, Alain Colas and the amazing Mike Birch were winning ocean races and they all raced double outrigger trimarans. The prospect of wave induced capsize was an issue. The development of multihulls was still experimental. Outrigger buoyancy and the shape of the hulls, and the volume of the hulls were still being developed. Wharram and Hanneke wrote an article on stability that concentrated on the idea that sail areas should be kept low an idea James had argued consistently as early as 1967 after the CSK catamaran Golden Cockerel capsized in the Solent while racing. They espoused a theory that only double outrigger trimarans were subject to wave induced capsize which was far too simplistic. The problems of roll inertia caused by the heeling of trimarans and low buoyancy outrigger floats certainly produced some wave capsizes but many combinations of wind and waves caused other multihull capsizes too.   Starting in 1968 James sold designs like Hina, Tangaroa, Narai and Oro were very simple with low rigs, and tiny cabins. Many were built by inexperienced “Wana be” sailors, and they did not always have the seamanship skills to sail the boats resulting in some disasters. However, many of the builders were able to achieve long ocean voyages all around the World. From the early 1980s after his life in Ireland with five women in a commune failed and he broke up with all but Ruth and Hanneke, James moved to Cornwall for the last 40 years of his life and designed small day sailing catamarans starting with the Tiki 21. He marketed the idea of holiday escapes and weekend sailing for people who did not reject land-based lives with jobs. Throughout his life James pitted himself against the mainstream and was critical of luxury catamarans which dominate the multihull market saying they were for western "land" people who wanted a boat that was like their apartments.  He was very critical of designs that could capsize easily because they were over canvassed, but the reality was that his designs could capsize too when owners or builders enlarged their rigs to improve speed and windward performance. The Wharram tenets of flexibly connected hulls, low multi masted (most were ketches or schooners) and often gaff rigged or at times junk rigged or using a version of a Polynesian sprit sail (and in his earlier designs using the spritsail itself) . The lightweight Tiki 21 and 26 models were both capsized in the hands of crews that did not appreciate that they had limits; this is true of most multihulls that inexperienced sailors or contrarily experienced mono hull sailors fail to detect that they are on their stability limit because they do not heel over. . Wharram never changed his opinion that multihulls had to be sold as safe family boats and freedom from capsize was an essential starting point. He could be quite forthright and was clearly not a man to suffer fools gladly particularly when those fools were his competitors like Arthur Piver, Derek Kelsall, John Shuttleworth and Richard Woods all of whom he criticised for being "city men" and that he thought put speed over safety from capsize to sell designs. James dismissed the arguments that multihull development was to be found in test tanks and computer programs and preferred to look to principles he derived from study of Polynesian designs and empirical sailing experience for all the answers. Relying upon his own experience and voyages he claimed to know what made multihulls seaworthy because of his sailing - a view which of course did not  give credit to the experience and ocean voyaging of other designers particularly Piver, Kelsall, Newick, Crowther and Shuttleworth all of whom had long voyages, and had also done trans-Atlantic's and other sailing experience that distinguished them as sailors who designed boats. James always established his credentials based on his Atlantic crossings and implied he had more Ocean experience than others. Perhaps the others chose to be more modest about their seagoing experience because they were also aware that their knowledge and expertise was very much evolving and it is evident particularly in the writing of Kelsall, Shuttleworth and Newick that they were aware that they still had a lot to learn. Pat Patterson for example was famous for his bestselling Heavenly Twins family cruising catamarans, but he had sailed extensively with two circumnavigations and several Atlantic crossings to his credit in his own designs about which he was incredibly modest. Comparing the state of the art in multihull design in the 60's with what is being designed and built now shows that the view that multihull design development had a long way to go in the 70's was quite correct.

But throughout his career James clung to his design principles established in the 50's of V shaped hulls, open slatted decks and canoe sterns with flexible beam connections. That said James’ sales success, the number of boats built to his plans and above all the number of voyages made in his designs are his epitaph. Many people empathised with James' values and his political, philosophical and lifestyle ideas teamed with his devotion to Nature and learning lessons from Stone Age sailors to build boats that owed nothing to modern mainstream yacht design. 
My limited experience of meeting him was about 22 years ago and I was happy to find that rather than the outspoken, opinionated and controversial man that I though he was, in person he seemed very approachable, and charming and he clearly had that effect on many that he met. He was seen by some as a "great" guru like figure. I do believe he cultivated his role as the great Jim leading his tribe of Sea People to a better place than suffering in mainstream wage slavery.  The early journals of the Polynesian Catamaran Association are available online and are an interesting read. They tell the story of how James gathered many aspiring catamaran sailors and builders to his designs. He had a vision of a great body of people sharing their experiences and voyaging and sharing the results. Sadly it did not quite work as he so inspirationally wrote. Some sailors of his designs lacked skills and experience. Unlike many designers he seems to have encourages his builders to be creative with the designs too which produced some odd interpretations of the plans -some more successful that others which caused breakups at worst and ugly aberrations of the designs. The film about the building of Tehini shows that the craft was rather roughly built with tar all over the hulls and roofing felt and tar used on the decks -not something you would see at Camper & Nicolson! The strange triangular cabin tops made her look very homemade and indicate that she was indeed built to a very tight budget. It is no surprise that the vessel was very short lived launched in 1969 she was deemed too rotten and unsafe to sail by 1985 and in about 1990 she was burned. Wharram's Rongo had been built in 1957 and was effectively a houseboat on a beach ten years later. In 1969 James gave her away to the Sea Scouts who sank her. when they tried to take her to sea. But some builders assembled beautiful craft to his plans and the Spirit of Gaia was built to professional standards and sails in Portugal under Hanneke's command.   
Petty quarrels in the Association and disappointing editors that came and went were an issue and eventually after the collapse of "James Wharram Associates" in Ireland James, who saw himself as terribly betrayed at the time although by the time he wrote his final book in 2020 he or Hanneke who co-wrote it, was able to see where a lot of the blame lay in James himself and his arrogance and a mistaken belief that taking part in the Round Britain Race courting publicity (in 1966, 70, 74 and 78) would give him the credibility and recognition he obviously wanted.

In fact all these racing adventures just showed up the shortcomings of the Wharram designs, the disastrous trimaran in 1966; Tehini would not go to windward with her junk rig in 1970 and abandoned the race again on the first stage; in 1974, Maggie Oliver one of his closest female companions sailed her and suffered the structural failure of the main beams and retired citing blown out sails;  in 78 a grp foam sandwich Tane Nui started to fall apart with major structural problems  and the 35 foot Pahi prototype proved so wet and exposed her crew had a terrible time and finished well down the fleet as one would expect for a boat with no keels and just small ineffective dagger boards and a tiny rig. 
James took over running the PCA in 1982 editing the Sea People Magazine himself. The association came back to life although there were rumbles that the breakdown in the association was caused by James because its editor decided to open up to other influences especially the Multihull Ocean racing and Cruising association. Other designers were also influential in the home build market like Kelsall Shuttleworth and Wharram's former protégé Richard Woods who had started up in competition (as James saw it). Kelsall was also marketing his own range of self-build designs in GRP foam sandwich. In time James handed over the PCA to others having believed that he had got it back up and running. Unfortunately, this developed into a dispute because James felt he was having his own business stolen by others who took up roles in the PCA and built their own website and business around Wharram catamarans. 
Others portrayed James as the controlling personality but the reality was that James' idealistic ideas for the PCA did not work because the whole enterprise cantered on the idea of James Wharram and that the boats were his concepts and designs. 
While James had been busy throughout the 1990's both running his own professional production business and sailing around the World in stages he believed that others in the PCA had started to build their own business about the Sea People community dream and also "improved" the designs creating their own rigidly monocoque versions some with the deck cabins he so loathed  and so  James was forced to take legal action (he told me) to protect his business identity and his intellectual property rights to 'Wharram Catamarans'. This dispute and the arrival of the Internet really killed off the PCA.  However what has grown up in its place over the past 25 years is a big community of people sharing stories of their Wharram Catamarans, their experiences building them and sailing them, on several social media and Internet sites. It seems that the spirit of what James intended when he formed the PCA in the 60's is alive and well in a thriving Wharram interest community like nothing else in the multihull world. 
It must be said that Wharram's wooden catamarans suffered extensively from rot due to what was essentially poor design with metal fittings and bolts being breeding points for water ingress and rot. By no means were they the only plywood multihulls to suffer rot because this type of construction especially back in the 70's before epoxy resin took over, is afflicted with rot when water ingress occurs. But also, the primitive low aspect ratio rigs and lack of keels meant that close winded sailing and powerful windward ability were never really attainable by Wharram catamarans. Strangely James was never a designer who drew his own designs. He would imagine what he wanted and was a boat builder, but he relied upon his associates and later Hanneke to do all the drawing of the plans and Ruth and Hanneke did all the mathematics. 
Later designs tried to address this with careful epoxy sealing of all the holes and lashing to avoid the metal bolts and fitting that caused rot. 
James wrote copious articles and papers with the help of his associates which with his books leaves a great record of his ideas. By the mid 1990's he and Hanneke produced their best designs after the Pahi 63; the home build Tiki 34 and 46 and the Islander professional designs. Later they developed especially "ethnic" designs like the Wanderer and Mana 24 a kit boat.
His final book People of the Sea is a fabulously produced gallop through his eventful life which encompassed great self-belief, courage, and the consequences human flaws too.
Sadly, as old age and dementia caught up with him, he was brave enough take his own life which in the context of Assisted Dying coming into UK law in 2025 shows that James was in many things a man well ahead of his peers.
James may not have really invented modern catamaran, but his story is heroic and unique to World multihull development. What he did was brilliantly promote his own types of multihulls (he designed catamarans, at least one proa and a trimaran) and his personal design concepts that are unlike any others. But above all James personified the spirit of adventure, self-sufficiency, and striving to live the life you desire. His individuality made him stand out and he clearly struck a note that many people were attracted to and was a most influential and inspiring character.