Charles Cunningham and his son Lindsay started experimenting in catamaran sailing in 1951. They first developed an 18ft catamaran which they named "Yvonne" after Charlie's daughter. After initial testing several alterations were made including an increase in length to 20ft, and the addition of "V"-bottoms. Finally in 1954 a set of plans were drafted and became available to the increasing number of catamaran enthusiasts. The Cunningham's built "Bleep Bloop" and sold the original "Yvonne". By late 1956 there were sufficient Yvonne class catamarans to warrant holding an Australian Championship in an effort to gain recognition around Australia.

In Western Australia interest in catamarans was quick to gain a foothold with six Yvonnes being built in 1957. Claremont Yacht Club was the original home for the cat's but they moved to the better facilities at Nedlands Yacht Club in 1961. The fleet in W.A. sail from The Cruising Yacht Club in Rockingham, with fleets once sailing from Geraldton, Safety Bay, Princess Royal Sailing Club, Nedlands and Claremont.

The state of Victoria has a strong fleet sailing from the Frankston Yacht Club, whilst South Australia has recently re-established a fleet from Victor Harbour Yacht Club.

Developments over the years have mainly been in the methods of construction and the types of materials used, leaving the distinctive lines and looks of the Yvonne unchanged. All wooden construction has now given way to fibreglass foam sandwich construction with the last 25 boats built being of this type. The newest 5 boats have been built in the association's full hull mould which has again simplified the construction method.

Possibly the most distinctive development has been the adoption of a new profile mainsail in the 1997/98 season, which has resulted in a more up to date appearance and a much more manageable rig. The 2004/5 season sees the introduction of the new assymetric spinnaker design. After trialling for about 3 years, a masthead design has been adopted with an area of about 23 sq. metres. The only restrictions at this point (September, 2004) are: 1) sail perimeter not to exceed 19500mm, 2) mid-girth not to exceed 3500mm, 3) top of halyard sheave bearing not to exceed 7100mm from base of mast, and 3) front of pole tack sheave bearing not to exceed 1800mm from the bow, measured from the midpoint between the two bows.

Conduct of the Australian Championships has reverted to a 3 states (WA, Victoria, SA) rotation system. The 50th Australian Championship will be held at Victor Harbour, South Australia in 2005/06 in what promises to be a landmark and well represented event.

Reg.# Name State Y1 Yvonne (Prototype) Vic Y2 Why Two (Bleep Bloop) Vic Y6 Felix SA Y8 Toowit Toowoo Vic Y9 Fantasy Vic Y11 Duet Vic Y14 Sea Wyfe Vic Y15 B.B. or Flash Vic Y18 Companion Vic Y19 Seas'f'Two Vic Y33 Wee Two WA Y43 Feline WA Y45 Dolphin WA Y47 Felix WA Y49 Unknown Qld Y50 Fair Winds Qld Y51 Jo-Anne Vic Y60 Schuss Vic Y79 Alluna WA Y81 Wongdoolie Vic Y85 Hellcat WA Y87 Chatrois WA Y90 Alpha Omega / Tui IV Vic Y93 Bob Cat Vic Y120 Hellcat Vic Y131 Moonglow Vic Y133 Imp WA Y138 Atalanta Tas Y144 Hi Fi SA Y153 Bali Hai SA Y156 Calypso Qld Y172 Moby Dick Qld Y176 Saracen WA Y177 Weona WA Y181 Minon WA Y186 Cutty Sark SA Y187 Vivace Vic Y195 Silhouette WA Y197 Jedda SA Y200 Kewarra WA-SA Y201 Riot WA Y202 Unknown SA Y204 Unknown SA Y208 Mauna Kea SA Y228 Duo Vic Y231 Double Trouble WA Y232 Toggle Woggle Vic Y233 Sea Witch WA Y241 Bloody Mary SA Y247 Sundowner WA Y248 Wongdoolie II Vic Y260 Diondra SA Y264 Vixen III SA Y265 Tamure SA Y270 Mistral WA Y271 Walkabout III WA Y275 Banshee WA Y276 Rotorene WA Y277 Windward Vic-SA Y283 Gemini Tas Y285 Kitten (Mach I) WA Y286 Roaring 40 (Tomkat) WA

Reg.# Name State Y287 Achilpa WA Y288 Unknown Tas Y291 Vamoose II Vic Y300 Pegasus Vic Y301 Southern Cross SA Y303 Aderwyny-More Vic Y304 Kitten Qld Y306 Su-Ton WA Y307 Co-Re VI WA Y313 Aloaha Qld Y315 Puma WA Y316 Contessa WA Y317 Felix II WA Y318 Hustler Vic Y321 Sea'f'Two Vic Y327 Terita Vic Y328 Gi Gi Vic Y333 Temptress II Vic Y340 Ditto II Vic Y346 Saladin Vic Y349 Spindrift WA Y350 Simba SA-NT Y351 Kon Tiki SA Y352 Sussanne SA-WA Y353 June-Eric SA Y359 Unknown Vic Y364 Skat Cat WA Y365 Alpha Omega II Vic Y366 Sans Souci Vic Y367 Patrica Vic Y368 Ros I Vic Y375 Unknown SA Y383 Capri III Vic Y384 Cinderella WA Y385 Checkmate Vic Y391 Caduceus V SA-WA Y397 Katmandu Vic Y401 Bronny SA-WA Y403 Pyewackett SA-ACT Y404 404 SA Y405 Patri SA Y406 Vixen IV SA-Vic Y408 Tawarri Vic Y413 Karina Vic Y416 Judy D Tas Y417 Skeeta V SA Y418 Zero SA-Vic Y422 Andromeda Vic Y426 Fitzy Vic Y428 Tabby WA Y429 Chinook Vic-WA Y432 Foxy Lady Vic Y433 Aztec Vic Y434 Barbarella Vic Y436 Touche Vic Y437 Sea Lion Vic Y438 Yucatan Vic Y440 Pacer Vic Y441 Cheeky Vic Y442 Psycho Vic Y444 Poseidon Vic

Reg.# Name State Y445 Squall SA Y448 Caduceus VI (Bagheera) SA-WA Y452 Up-Tight SA Y453 Bronny II (Maverick) SA-Vic Y454 Stirrer (Tomkat II) WA Y455 Mauna Kea II SA Y457 Sabre (Allikat) SA-WA Y458 Artful Dodger (Marlin) WA Y459 Caduceus VII SA Y460 Putska WA Y462 Sundancer (Sundowner) WA Y464 Charger Vic Y466 Ragtrader Vic Y468 Pink Pussycat Vic Y469 Pacer WA Y470 Corsair (Attitude) Vic Y472 Katkandu (Tigress II) WA Y473 Taurus SA Y474 Rhapsody (Moggee) WA Y477 Bushwhacker SA Y480 Bootlegger Vic Y481 Kestrel (Sidewinder) SA Y482 Nyphea SA-Vic Y484 Fair Dinkum SA Y485 Top Cat SA Y486 Phoenix Vic Y487 Sabre II SA-Vic Y488 Felis Velox (Scaramouche)(Predator) SA-Vic-WA Y490 Posiedon II Vic-SA-WA Y491 Mauna Kea III (Cazaly) SA-WA Y492 Warian Vic Y493 Eclipse (Sundowner) SA-WA Y498 Excellerator (Asylum) WA Y500 Touch of Glass WA Y501 Ricochet (Ric O'Shea) WA Y510 Merlin Vic Y511 Goolagong II (Cougar) WA-Vic Y512 Felix WA Y513 Tomahawk WA Y514 Another Moggee WA Y515 Red Zeppelin WA Y516 Tz-Aire Vic Y518 Feral WA Y519 Phoenix Vic Y520 Dark & Stormy WA Y521 Synergy WA Y522 Hi-Tech WA Y523 Mr Touchy Feely Vic Y524 Assegai Vic Y525 Secret Men's Business Vic Y526 Millenium WA Y527 Tinkerbell (Tinker's Cuss) WA Y528 Punk in Drublic WA Y529 Buzzard WA Y530 Primus WA Y531 Kinetic WA-SA Y532 Shooter WA Y533 ? ? Y534 ? ? Y535 Pleasure & Pain WA Y536 Trois aux Biches WA

2003/2004 National Championships
The 48th Australian Yvonne 20 Catamaran Championships were sailed at the The Cruising Yacht Club in Rockingham, Western Australia from the 28th of December to the 4th of January. The new National champion is Tomahawk, sailed by Kevin "Goof" Phillips and crewed by Lindsay Snow. Results are shown below.

Place	Sail#	Boat Name	Crew	State	Ht1	Ht2	Ht3	Ht4	Ht5	Ht6	Ht7	Final Pts
1	Y513	Tomahawk	Kevin Phillips/Lindsay Snow	WA	2	2	7	1	1	1	4	11
2	Y522	Hi-Tech	Jeff Payne/Ben Hooper	WA	3	1	5	2	2	2	5	15
3	Y530	Primus	Neil Brett/Andrew Booth	WA	6	4	6	3	4	3	2	22
4	Y528	Punk in Drublic	Ashley Snow/Brendan Woods	WA	1	5	1	5	6	5	8	23
5	Y521	Synergy	John & Dean Buonvecchi	WA	4	3	15	4	9	10	1	31
6	Y531	Kinetic	Paul & Michael Hawkins	SA	7	7	2	6	17(DNF)	6	6	34
7	Y536	Trois aux Biches	Dave Randall/Geoff Woods	WA	5	17(DNF)	3	7	5	13	3	36
8	Y532	Shooter	Rob McGavin/Ross Taylor	WA	11	6	12	9	3	4	9	42
9	Y535	Pleasure & Pain	Steve Gorbould/Bodie Logan	WA	10	9	10	11	7	15	10	57
10	Y520	Dark & Stormy	Graham & Alistair Hunt	WA	9	10	8	17(DNF)	17(DNS)	9	7	60
11	Y514	Another Moggee	Adam & Daniel Taylor	WA	15	11	13	8	11	7	13	63
12	Y529	Buzzard	Glenn Randall/Jason Taylor	WA	8	8	4	10	17(DNF)	17(DNS)	17(DNS)	64
13	Y515	Red Zeppelin	Ryan Wall/Scott Gorbould	WA	12	13	9	14	17(DNF)	8	12	68
14	Y518	Feral	Rob Squirrell/Chris Timewell	WA	14	12	11	13	10	12	11	69
15	Y501	Ric O'Shea	Les Thomas/Trevor Taylor	WA	16	15	16	12	8	11	15	77
16	Y527	Tinker's Cuss	Roland Cooper/Jon Stocker	WA	13	14	14	17(DNF)	17(DNF)	14	14	86