IRC Rule: Symmetric vs Asymmetric

Published on April 23rd, 2020

For Afloat.com, Barry Hayes of UK Sailmakers Ireland goes through the different options for racing boats going ‘Symmetrical’ or ‘Asymmetrical’ with their spinnakers. What’s best for IRC and why?


In the past 15 years, spinnaker options have increased considerably. Prior to that, it was fairly straightforward. You bought a light air symmetric spinnaker, a heavy air version of the same, and maybe a reaching spinnaker. In recent years, however, asymmetric spinnakers have become a lot more efficient and some yacht builders, particularly J Boats, feature them almost exclusively on their models.

The following is an analysis of which option is better for racing inshore/offshore.

First the pros and cons of each option:

Asymmetric Spinnakers

Pros
• Easier trimmed and handled
• IRC rating allows larger asymmetric spinnakers for the same rating, relative to symmetric spinnakers
• Very efficient when reaching as the shape allows better exhaust of the air across the leeward side of the mainsail.
• Code zero models (very flat asymmetrics for close reaching) is a must for offshore boats

Cons
• Needs a sprit or prodder to set them properly away from the bow.
• They don’t run as deep and efficiently as symmetric spinnakers.
• In heavy air, they sometimes can wrap around the forestay when gybing
• Time is always lost gybing, compared to boats with poles

Symmetric Spinnakers

Pros
• Once above 12 knots, they are very efficient running with pole pulled back.
• Tactically, they offer an experienced crew greater options downwind.
• Very little time lost while gybing.

Cons
• Expensive on IRC rating – On a J/109, converting to a symmetric costs about 7 points if you want the same sized spinnaker
• Not as efficient when reaching due to shape
• More difficult to hoist and trim properly

Full report… click here.

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