The nimbler, sexier (see pic) SB3s should make for a much more lively boat within the cozy confines of the dockland venue, but the real difference will be the format of the racing.
This year, the Liffey Challenge is a random pairs event, pitting teams of two boats against each other in quickfire bursts of team racing.
In Random Pairs racing, the team with a boat in last place loses, so the goal is to sail your competitors into last place, while shepherding your team-mate into a better position. Racing is in very close quarters, highly aggressive, and dependent on skilful boathandling in tight spaces.
The Liffey Challenge sees spinnakered boats sail right up to the quay walls, using every inch of available space to get an advantage over the competition.
Racing begins at 11am today, continuing through the day, and if you can't make it down to the river in person - check out this webcam on the roof of Liberty Hall.