Will DN iceboat rig be fast in the water?

by Gordon Upton
Every now and then, something comes along in sailing that really gets people talking.

Back in 1937, in the Detroit News hobby shop, a small ice yacht was first built that would become the most popular design ice yacht class in the World. The DN is now raced wherever the lakes freeze over, and they are fast, with 100kph not uncommon, and this is largely due to its unique rig design.

In the last couple of winters, it has gained the attention of the Dutch composite designers and carbon boat builders Holland Composites, a notable supplier to the A-Cat Class. But can the DN rig with its massive sidebend work in this development class too?

Three-time A-Cat World Champion Mischa Heemskerk has been their chief test pilot for Holland Composites, and is trialing a version of that DN rig before the 2024 A-Cat World Championships in Punta Ala, Italy.

This version has an 8’5m carbon tube mast – 500mm lower that the standard A-Cat mast – with side fairings to make it into a wing mast and a luff grove. It is stayed at the usual class hounds point, but has no spreaders commonly seen on the masts.

Instead, it has adjustable Dyneema lower shrouds that are trimmed to allow a considerable range of sideways bend. This allows the power of the mast to be much more fine-tuned when going upwind and providing more controllable rig power. The lowers are then tensioned up to straighten the mast when going downwind.

So far, admittedly in the highly skilled hands of Heemskerk, the rig looks to be of a similar performance to the current setup. This is no mean feat, as the modern A-Cat rig is a hugely efficient driving power source already, so most modifications frequently result in a drop in efficiency.

Their DN rig is still in the early stages of testing though, but the rig shows potential. It could bring easier, more controllable foiling power to the A-Cat if it can be optimized. This is a long road now to explore all the aspects and nuances of the design.

Can it perform across the 5 to 22 knot class wind range? Will it work as well on the more popular and numerous Classic non-foiling version of the boat? With the mast designed for up to 2.5m of sidebend, can mast breakages be reduced, together with associated insurance costs?

There are as ever, more questions than answers, but this is the excitement of a high-end development class sailing boat. We all await in anticipation. We might see if the DNA team opt to use it in the World Championships. Maybe once we get used to that bizarrely bent mast, things could slowly change?