All four designs attracted plenty of analysis when images surfaced of some of the AC75s foiling. Big differences in the boats are apparent.

After the Defender Emirates Team New Zealand and the US Challenger NYYC American Magic, the Italian team of Luna Rossa Prada Pirelli launched their boat on October 3.

Patrizio Bertelli, president of the Luna Rossa Prada Pirelli team, said at the launch: "This is our sixth America's Cup challenge, but launch day is as exciting as ever: it is the magical moment that brings together many months of work and dedication and the anticipation of finally seeing on the water what was until now only a design".

A couple of days later in Portsmouth, Julia Ratcliffe, the daughter of the syndicate owner Jim Ratcliffe, did the honours to name Ineos Team UK's AC75 'Britannia', in homage to one of Britain's most famous racing yachts.

As the Protocol of the 36th America's Cup doesn't allow the teams to hide their boats, the new AC75 monohulls were photographed and the images went viral.

The most recent launches from Luna Rossa and Ineos are again different from Emirates Team New Zealand and NYYC American Magic's interpretation of the AC75 Class Rule.

America's Cup media have reported that design teams have spent a lot of time exploring different hull shapes within the Class Rule limits, looking for a shape with minimal drag in light-wind displacement mode while also addressing the stability needed to generate thrust for take-off.

Differences in hull shapes are most evident as there are no significant limits on hull structure other than a handful of standard AC rule limits.

"There's a huge amount of innovation in the design and build of the AC75 - more than we saw in the AC50s in Bermuda," Emirates Team New Zealand head of design Dan Bernasconi said at the launch of their AC75 in Auckland.

It is evident that the Kiwis and the Italians are choosing one approach, while Ineos Team UK and American Magic have designed their boats for other reasons. It's also rumoured that Emirates Team NZ has been training without the use of foils.

Ineos Team UK's hull appears to be the most radical. According to America's Cup media, the bottom has a very clean scow like line similar to NYYC American Magic, while the deck layout has a completely new design, with a very flat and low bow, slab sides and a straight sheerline towards the stern. The British hull seems wider, with the foil rotation points (whose distance is fixed as per the Class Rule) appearing to be inside the hull compared with the other teams that have a dimple treatment where the carbon foil arms stick out from the hull.

Luna Rossa Prada Pirelli's design has gone in the opposite direction with a boat similar but more radical than the Defender's. Despite a more traditional bow, the sheerline is quite pronounced and tapers towards the transom.

Newcastle Cruising Yacht Club has kicked off its Sailing League, with the region's best sailors going head to head on Elliott 6s. Launched on Monday, the series will decide who represents Newcastle in the Australian National Sailing League early next year. The Sailing League features some of the Hunter's best skippers, including Joe DeKocke, Richard Howard, Glen Collum, Janease Graham and Harry Miller, racing in a six-week point score series. Newcastle Cruising Yacht Club will hold youth racing on Monday, with open age racing on Tuesday and women's racing on Thursday nights in the harbour's western basin.

Palm Beach Motor Yachts is set to introduce the latest model to its range, the Palm Beach 70. The boat was designed to appeal to customers looking for a larger Palm Beach. The interiors of the latest model will be finished with golden teak throughout her three-stateroom layout. The spacious flybridge has numerous social areas to welcome family and friends aboard both in large gatherings and in more intimate spots. The yacht is expected to achieve a 32-knot cruising speed and a top speed of 38 knots with IPS, while still offering efficient cruising. The Palm Beach 70 will be introduced to the world at the Fort Lauderdale International Boat Show starting on October 30.