Tuesday, 7 September 2010

DNA light weather performance

pic by Megan Brewin
Pic by Fredirico Rafaelli

I got a few questions about the light weater performance of the DNA which will be answered here.
Most people have seen that the boat is fast in medium and strong breeze, but how does it in the light stuff?

In Cesenatico we had sometimes very light stuff and Stevie did great but not better than Glenn.
In those conditions the rig really matters, the more power you get from the rig the better you go especially downwind. Both Glenn and Stevie did use very powerful rigs. Both boats have the fore beam behind the middle of the boat and both helmsman where clearly in front of the fore beam while drifting downwind. The DNA has quite some volume and can be sailed without wake that way.
In theory the DNA has some what more wetted surface due to its square bottom and transom, but in reality if you can get the transom out of the water is the same as the Tool or other high voulme boats and still better than a Flyer 1 or 2. In the ligt stuff you have to pull up the boards downwind, the boat is slow if you don't.  If you do it the boat wil glide very smooth over the water with no wake and no noise.

Upwind you would expect that the straight boards boats are quicker, but we have not seen that to our surprise and that of others. Once you pop a hull the boat is fast. Due to its flat bottom the boat has a bigger resistance for going down and therefore you can pop a hull just a bit earlier than on the  'older' designs.
If you sit or hike out in front of the shrouds, the transom is out of the water and boat is longitudinal stable and feels very light. The lack of noise is quite amazing, so little wave drag and low induced drag.
We are not sure what the best setting is for the boards, if you add rake you will get more lift (and height) but that will be cause more drag as well.  Somewhat less rake is less drag which should be faster theoratically but we have not seen that in races. What makes a difference is pull up the windward board once you can foot to the first mark.

The ligh weather performance is one of the reasons we did not further reduce the amount of rocker. The boat has less rocker than the Nikita, but also has a bigger overall volume to compensate for that.

The wind limit as stated in the Championships Rules has gone up from 4 knots to 5 knots. In 5 knots you certainly can pop a hull upwind so no more drifting in the big Championships.

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