In September and October, 2018, Nacra Sailing endeavored to test moving the rudder position on the Nacra 17 inboard from it’s current position.
2 positions were tested
- 80mm inboard from standard
- 220mm inboard from standard. (The 220mm position is the maximum inboard position available on the transom.)
Findings at 80mm in:
First test in 20kntos flat water
- Hard to handle the boat as rudder went in and out of wake of main foil.
Next tests 10-15knot
- Low drag upwind as the stock not sitting outboard of the sheer line of the hull. Down wind was not much different in low foiling
- High foiling the same issue with wake as test in 20 knots.
- Gybing was more unstable as hitting wake would turn the rudder.
Findings at 220mm in:
First Test in 10-23knots
- Much worse than 80mm position. It was very hard to hold the tiller when rudders where in and out off the wake.
- Also made the gybing very hard to do and would try and self steer.
Rudder 225mm adding a main foil bearing with 0 degrees of angle of attack.
- Was very similar to the 80mm rudder position in stability
- Hard to tell about 0 degrees main foil performance as only had up to 10 knots over the days we had them in. (need more testing).
- Down wind slightly harder to control in the gybes.
- Upwind was hard to tell performance difference as was light wind.
Overall
Tester Rupert White, feels like the current position of the rudders is the safest as the boat is much easier to handle when sailing in a straight line and when gybing. The unstable rudders would cause more danger while sailing than the position.