AC72 sail area reduction concept
[Source: Pete Melvin, AC72 Class Rule Consultant] To: Prospective America’s Cup teams, contributors to the rule, and other interested parties
We now have a suitable proposal to incorporate into the AC72 Class Rule regarding a wing area reduction method. After performing additional research into the feasibility of the previous 4m removable tip concept, we concluded that this concept would not significantly improve the safety and controllability of an AC72 in higher winds, and therefore eliminated the removable tip in the latest draft (2.0) of the AC72 Class Rule released Oct 6.
Attached are diagrams showing the wing measurement grid and conceptual sailplans for the standard and small wings. The small wing will effectively be very similar in profile of the standard wing but with the height reduced by approximately 10 meters. We believe this wing reduction method includes the following benefits over other choices:
1. A reduction of 10m in wing height will significantly improve the safety and controllability of an AC72 in higher wind speeds. The minimum hull-flying true wind speed is estimated to increase from approximately six knots (with the 40m wing and Code 0) to twelve knots with the 30m tall wing without headsail.
2. Competitors can utilize existing lower sections of the wing spar and simply add a new, smaller upper section of wing spar.
3. Competitors could convert a standard wing to the small wing while using as much of the standard wing parts as possible.
4. When a small wing is used, only one Gennaker is to be on board the yacht.
We recommend that the following also be implemented:
* Requirement for teams to have a small wing be delayed until late 2012 or early 2013. This may allow teams time to modify an existing standard wing.
* The Regatta Director to determine what wing is to be used by Competitors for a regatta or on days within a regatta.
* The Protocol be amended to allow for an extra two small wing mast sections be included within the wing spar limits and to allow the change from a full
wing spar to a small wing spar without that spar being counted as a new wing spar.
This does not limit teams to only two small wing spar sections but reflects the requirement to allow wing spar development over both wing configurations.
Please let us know your thoughts about this sail area reduction concept , and send your comments to me at the ACRM email address for class rules matters (email@example.com) by no later than next Monday, 11 Oct, 2010.