135% vs 150%
Many times in very light winds a sail will experience a ''separation'' of air flow due to its too full shape. This is not a stagnation or stall as commonly found when incorrectly setting the angle of attack. The separation will show sometimes as a recirculating ''reverse flow''. For ultra light winds and once ''up to speed'' it sometimes will benefit to flatten the sails to prevent such an airflow separation. The larger the draft and the larger sail will become more unstable for flow attachement under these. Lightweight Tell-tales mounted all along the sail will show such separation. Tell-tales made from mini-audio cassette tape will work best, as tales made from ripstop may be too heavy in ultralight condition. When flow separation conditions are evident, this is time to FLATTEN a sail.