The Nacra17 class are making some changes to the Rudder Systems for the Paris Quadrennial.
There are two safety improvements the changes to the rudder/elevator system should offer:
- Teams should be able to sail downwind with the amount of rudder rake they prefer, instead of hoping to survive the downwind with the rudder rake optimized for the upwind.
- If a sailor falls into the water and hits the rudder or elevator, as has occurred from time to time, if the system is not at maximum lift then the spring within the system may give slightly on impact, somewhat decreasing the point loads on the sailor at impact. Note, this is a theoretical gain, and has not been tested.
The first change is to adopt an updated elevator, seen below (blue is old, green is new) .
The new elevator has blunted edges and a blunter central ‘torpedo’, along with being slightly offset to leeward.
The blunting is aimed at decreasing the chances of cuts should sailors fall into the water and be struck by the elevator.
The offsetting is to incrementally reduce the likelihood of being struck by the elevator.
The second change is an adjustable rudder rake system.
The existing rudder rake is adjustable, but the system and class rules do not allow for it to be adjusted during racing.
The change is simply a new top gudgeon and two pulley’s added to the transom. The pulleys lead the control lines forward for the crew to adjust while sailing.
This will also allow differential rake, with the windward elevator to have negative lift while the leeward elevator has positive lift, marginally increasing the power available to the sailors.
The update also increases slightly the range of adjustment offered to the sailors, going from 3.5 degrees total span to 4.5 degrees total span.
Overall, this should help the boat foil upwind in a wider variety of conditions, allow the boat to get foiling more easily, and do both without risking a rise in the optimum crew weight.
These changes may only be adopted after the 2021 World Championships championships.
No further changes are planned for the Nacra 17 until the conclusion of the 2024 Paris Olympics.
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