Big Pimpin’
Here’s the latest from the Ask Ullman Series – If you have a question for the experts over at Ullman Sails about anything from sail construction to sail handling and tactics, send them to the Ed and we’ll get ‘em answered.
Ullman Sails’ Larry Leonard sat down to answer this round:
Q: We heard you got onboard Abu Dhabi Racing for a few inshore race days in Cape Town last November as a guest VIP. We all watched the virtual tracker from our couches or desks at work. What tactical or boat handling tips to be learned from watching the Volvo fleet? What surprised you the most when you jumped onboard in Cape Town?
A: The biggest surprise was the shape of their downwind sails and their VMG angles. These boats are very fast off the wind. As a result they sailed at very low apparent wind angles. Most of the time they sail at 90 degrees apparent.
To sail these VMG angles the downwind sails must be designed to be more reaching oriented then your typical IRC or PHRF boat. So the sails are much flatter and set using bottom up and top down furlers.
In terms of tactics I think we all saw how AIS and the other tracking information available to the boats minimized risk-taking and separation in the fleet. Constant contact between all the boats removes any tactical advantage a boat may have. Prior to this race boats only had to check in and report their position every 12 hours. This time every move a competitor made was reported by AIS. This made it almost impossible to take advantage of a different strategy.
Q: I would like to know more about proper telltale placement on main and jib. Everybody seems to have their idea of where they should go, or even if they’re needed at all. Surely there is a definitive answer?
A: Telltales are just one of the tools that measure performance. Telltales are evenly spaced along the luff of the jib, at 25%, 50%, and 75%, and approximately 400mm aft of the luff tape. By observing them, the helmsman and trimmer can tell when the wind is no longer attached to the sail and can make adjustments in their heading or trim to correct this problem.
On the mainsail telltales are placed at the end of each batten and sometimes at 50% of the chord at 25%, 50%, and 75%. The most important telltale is the one placed at the end of the top batten. This telltale should fly most of the time if the sail is trimmed properly and with the correct amount of twist.
Q: How often should we be thinking about altering the position of the draft in our sails? Multiple times a leg? Once a leg? Once a race? More or less in heavy breeze compared to light air?
A: Altering the position of the draft in a sail is fluid and changes with every change in sail trim. This is normally achieved by adjusting the halyard or Cunningham. Tensioning one of these controls moves the draft forward while easing moves the draft aft. Seeing these changes is made easier by looking at draft stripes that are normally located at 25%, 50%, and 75%.
Realistically on the racecourse you cannot pay such close attention to changing the draft position with every change in sail trim. Instead, finding settings for various points of sail in practice, pre-start and in-between races is the best way to ensure you at least know where the draft should be for any set of conditions.
