The Basics

The J105 class is a "one design" which means that all of the boats are the same. However, over 600 J105s have been built since 1992 and JBoats have made substantial changes over the years. Akula is a 1992 boat, number 16 off the production line. This fact has both positive and negative consequences for racing.

Spinnaker Handling - The J105 has a 89m² asymmetrical spinnaker tacked to an extendable bowsprit. In under about 12kts of wind, we sail hot angles to keep the speed up. Between about 12 and 25kts we sail as deep as we can without collapsing the chute - typically between 155 and 162 TWA this is where the trimmer really gets a workout. In over 25kts Akula will plane and we heat-up the angle again to get her flying. Takedowns in high wind conditions can be challenging. Check here for the Akula sequences.

Hull - Akula's hull is pre-scrimp and is lighter and stiffer than the newer boats. In fact, to get to the proper racing "sink" Akula requires 2 batteries, full fuel & water tanks and 508lbs of lead ballast. J105s are available in galley aft and galley forward configurations. Akula is "galley aft", which is better for weight distribution by keeping the fuel tank centered over the keel.

Under the water - Akula's keel and rudder were untouched from the factory. I had a limited scope bottom job done in 2005 to make them work better. The keel is oversize at max width and per specifications in the last third of the foil chord. The training edge is  bevelled - more details here. The J105 Keel offsets are here. The rudder offsets are here.

Rig - Akula has a 1998 mast and rigging, and a 2004 boom. The rig settings are per the North Tuning Guide with some custom settings that depend on the wind speed.

J105 Polars

Gear Changes

Sail Settings

Quick Tune - turns cumulative from Base