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Keyword : keel
Results 1 - 5 of 46
Towards Unsteady Approach for Future Flutter Calculations
This paper describes insights into keel and rigging loads
obtained through a data acquisition system fitted on the
fleet of Volvo 65 yachts during the 2014-2015 Volvo
Ocean Race. In the first part, keel fin stress spectra are
derived from traces of canting keel ram pressures and keel
angle; these are reviewed and compared against equivalent
spectra obtained by applying methods proposed by Det
Norske Veritas - Germanischer Lloyd (“DNVGL”)
guidelines and the ISO 12215 standard. The differences
between stress spectra and their validity are discussed,
considering two types of keel: milled from a monolithic
cast of steel, and fabricated from welded metal sheets. The
second part discusses predicted and actual rigging working
loads for the Volvo 65 yachts, and considers how safety
factors vary between design loads proposed by DNVGL
and actual recorded loads.
Sailing is a sport and activity that takes a long time both
to learn and to master, as much of its competence-based
knowledge is acquired through experience. Experiencebased
learning is very important, time-intensive, and the
factors for success are often tacit and hidden. Should these
success factors become explicit and salient, learning would
occur faster and produce obvious competitive advantages.
This research was conducted by embedding on-going
research results into two competitive sailing teams racing
in different classes, one offshore keelboat racing with a
crew of eight, and a one-design Star-class racing yacht with
a crew of two. The data collection consisted of
observations, interviews, and video recordings. The results
were also verified with the crews to catch biases in the
analysis process. A jibe, a specific but common maneuver
was analyzed from the perspective of Common Ground
within Joint Activity.
Maneuvering a competitive offshore sail racer or a
previously Olympic Star-class yacht are tasks that fulfill
the requirements for Joint Activity. A high level of
Common Ground is required for the effective coordination
needed in order to perform at a high level and maintain the
safety of the crew and equipment.
Breakdowns in the coordination of maneuvers were
observed, although they must be recorded on video for
higher analysis reliability. To achieve greater validity,
more and different maneuvers should be considered within
the analysis.
By better understanding the factors for success, sail
racing teams can more quickly gain competence and thus
competitive advantages.
The research analyzes the teamwork found in sailing
from the perspective of Joint Activity and Common
Ground and provides insight into how to achieve
performance improvements more efficiently.
Exploratory Study on the Flutter Behavior of Modern Yacht Keels and Appendages
As a result of the tremendous increase in the speed of racing yachts over the last 2 decades, keel flutter has appeared as a
major technical issue for designers to address. Recently the IMOCA class rewrote its keel scantling rules, in part to address this issue.
Flutter occurs when different natural frequencies of a lifting surface (wing, keel, rudder, hydrofoil etc.) combine together causing a
coupling in the motion that draws energy from the surrounding fluid. The vibration or motion is self-excited and its amplitude grows
quickly, leading to dangerous and sometimes catastrophic outcomes.