Some of them are still sailing today. It is a high performance boat but isn't so fast that it needs a huge piece of ice. You do not need to be a 20 year old Olympic athlete to be competitive. Many of the fastest sailors are in their 50's and 60's. The DN is a reasonably strict one design boat so this years winner will not be next years barge.
Most sailors find racing offers the most challenging and exciting aspect of the sport.
The class has approximately 1000 members in North American and another 1000 members in Europe. The Association publishes several newsletters and a yearbook each year. The current newsletter and yearbook will be sent with membership. If there is a club in your area, contact them. They can offer ice condition information, racing programs and building advice.