Bethwaite started sailing 18ft skiffs in 1974 crewing on KB, before moving on to the boats 9Sports, Singapore Airline, and Mutual Acceptance. Bethwaite won his first 18 ft Skiff World Championship as crew in 1987 and again as skipper in 1990 and 1992. He held several positions relating to the 18 ft class, including secretary of NSW 18 ft Skiff Sailing League, manager of the Super Skiff Series, and Skiff Grand Prix. At this time, Grand Prix Sailing was covered on TV. Internationally, his partnership with Alex Gad developed media driven sailing events throughout Europe, the U.S., and Mexico that resulted in three Sport-Tel awards.^{[citation needed]}

In 1980 based on a stretched Tasar Dinghy hull, he designed the first of the trilogy of Prime Computer 18 ft skiffs. It had a crew of two rather than the usual three which made sailing the boat difficult when handling the spinnaker pole and its complex wire bracing. It was this complexity that made Bethwaite design the Prime Mk2 with a fixed bowsprit and asymmetric spinnaker. To keep the weight down, the hull was made of balsa wood and weighed just 130 pounds (60kgs).

Prime Mk3 was also made of balsa wood, had a wingspan of 26 ft, and weighed just 99 pounds (45kgs). This was later used to make a plug for the standardized B18 class.

In 1994, Bethwaite designed the 49er which was a new high performance skiff.^[6] In 1996, it was one of 15 entries considered by the ISAF selection competition for the upcoming 2000 Sydney Olympics. ^[7] The Olympic committee selected the 49er.^[8][9][10] From the 2000 Olympics and onwards, the 49er sailed with country flag designs covering the entire spinnaker, making it clear which boat was which.^[11]

In 1998, the smaller 29er was designed for the international youth market.^[12] The 29er has been given International Class status^[13] In 2004, he worked with Martin Billoch and Chris Mitchell to design the SKUD 18, a ballasted skiff for disabled sailors.^[14] From 2008 through 2016 this boat has been raced at the Paralympic Games.^[15]

In 2012, ISAF held trials for a women's high performance boat to race at the Olympics. Bethwaite submitted the 29erXX, a souped up 29er with bigger sails. Although this boat lost out, the winning entry, the 49erFX from Mackay Boats (which developed a new mast and suit of sails) does feature Bethwaite's 49er hull.^[16]

Julian continues his father Frank’s pioneering designs in a similar manner – constant improvements looking for more speed from simplified designs. Here’s one example:

• The annual cost (1986) of an 18ft skiff was $120,000, and this high price had a negative impact on the sport, so Julian “consumerised” his Prime Mk3 to create the B18.
• The enormous loads from the boom vang required a “ram-strut” in front of the mast. This worked well but prevented a self-tacking jib.
• GPS data highlighted a needed improvement then tacking and jibing because the speed dropped from 14-15 knots to 2-3 knots, mainly because the crew had to stop to re-sheet the jib.
• The rig was re-engineered to manage the enormous load pressures which made room for a self-tacking jib. This ensured that the boat did not slow down.
• The crew could now move without restriction, enabling the ability to stay on a plane through a tack or jibe.
• Maintaining at least 7 knots through the manoeuvre meant that large rudders were no longer needed, so they were reduced in size, had a more of a slab design found in commercial planes, lower drag, and a more balanced feel.
• Skiffs would raise the centerboard at times for more speed. This made spinnaker sets and drops more difficult. With better acceleration through tacks and jibes, the centreboard size could be reduced which eliminated the need to raise it, so the extra space made tacking and jibing even faster.
• The crew was now able to run from side to side without stopping so the skipper could turn the boat faster. This enabled faster and deeper, and tacks and gybes.
• The increased speed made the spinnaker more sensitive to changes in the wind pressure and strength, so the spinnaker could now be smaller and flatter, resulting in even more speed.
• As a result, the spinnaker pole length was reduced which moved the center of effort back. This made the boat more balanced and easier to steer, so the rudder had less drag in the water.
• With the improved balance, the skipper could sail the boat heeled to windward, which improved speed again.
• The shorter mast, shorter pole, smaller foils, and smaller sails reduced the loads on the boat, which resulted in lighter boats, and a lighter crew weight to control them. This meant that the boats could point higher without losing speed.

Up until then, 18ft skiffs carried as much sail area as possible which them spectacular to watch but difficult and expensive to sail. These incremental improvements resulted in what Frank called “the end of the big boat era.” In 1997 this simpler, faster design was made the standard for all 18ft skiffs. The reduced costs made them available to a wider and more competitive global market.

List of designs edit

• 1978 assisted Ian Bruce and his father, Frank, with the design of the Laser 2.
• 1980 started skiff designs that included three two-handed Prime Computers designs that pioneered the asymmetric spinnaker system.^[17]
• 1987 designed the B14 skiff.
• 1988 designed the B18 skiff, a consumerised Prime Mk3.
• 1994, designed the 49er skiff.
• 1998 designed the 29er youth skiff trainer.
• 2005 collaborated with Martin Billoch and Chris Mitchell to design the SKUD 18.

• 1999 awarded the Royal Institute of Naval Architects Award for Outstanding Achievement in Small Boat Design (for the 29er and 49er).^[18]
• 2000 awarded the Australian Sports Medal.
• SeaHorse award for innovation and safety for KeyBall trapeze system developed with Allen Brothers.^[19]

• 1st Cherub Australian Championships 1975
• 1st Tasar Australian Championships 1977-8
• 1st Euro 18 ft skiff Championships 1992
• 1st B14 Australian Championships 1992
• 2002 – 2015 designed Trilogy, a 32 ft (11m) trimaran that won 9 OMR (Australian Multihull Regattas).

• 1st Cherub World Championships 1970. (Crew)
• 1st 18 ft Skiff World Championships (crew) 1986 Entrad
• 1st Grand Prix Champion (crew) 1987 Goodman Fielder
• 1st 18 ft Skiff World Championships 1990  AAMI
• 1st Grand Prix Champion 1990  AAMI
• 1st 18 ft Skiff World Championships 1992   AAMI
• 1st Grand Prix Champion 1993  AAMI