DN NA Class

what is the purpose?

To help hold your head up.
More discussion here: http://dnamerica.org/forum/index.php?topic=784.0

The DN is physically demanding.
It reminds me of running when I was a mere youth. The faster you want to go, the more it's going to hurt.
High loads at high speed require lots of upper body strength to handle the main sheet with precision.
Want an edge at the start?
Racers who make running part of their physical training program are exceptional starters. Many also ride mountain bikes in the off season for leg strength.
All the top racers, and also mid-fleet racers like myself, work out regularly.
Once I was asked why I didn't have shock cord on my helmut.
"I work out at the YMCA three times a week," I said.

Stress physical fitness year round; it's good for iceboating, it's good for life.

Randy Rogoski

Tried it, don't like it.

I find the pressure aggravates my bone spurs in the neck.  I get very sore the next day.

I exercise so I don't need it.  Curls with heavy helmet on in the months prior to the season, and lots of sailing time during.

I also like to hold my chin guard with the idle hand when the neck gets tired.  Less windage than the hand-on-head technique.

Some love the bungee neck support.  The experienced guys using it include a small pulley so they can look over their shoulder at marks and in tacking and gybing situations.  Some make a strapbasket or a loop of bungee to get in.  Some use a trapeze harness.

I would suggest getting a good down-hill ski helmet with a chin guard from ReliableRacing.com  their stuff is good.   Good helmets are light and protective.  Look for conformance to a standard for more protection.  Their clearance stuff is cheap, too.

Ken