Tuning: NACRA F17

Nacra F17 Carbon Mast Tuning Guide.               Effective date:  June 20, 2008


The information provided comes directly from years of testing and sailing.

By Bob Curry, 2004 / 2007 NACRA F17 North American Champion

Rudder Alignment

Rudder alignment should be set to 1/32”to no more than 1/8” toe in.  With rudders down and locked, measure fore & aft on the rudder, 12” down from the bottom of the lower casting and level with the bottom of the stern. The tiller arm to cross bar space should be equal on both starboard & port sides before tightening the set screws.

Daggerboard/Rudder Tuning

Careful tuning of the daggerboards and rudders is important to prevent cavitation. Rounding of the leading edge seems to be more important than getting the trailing edge sharp. For the trailing edge, thinning of the foil from about 1” forward to an edge about 1/16” thick seems to work best.



- Skipper sitting on the side> Boards totally down.

- Skipper hiking almost on trapeze > Boards totally down.

- Skipper on trapeze > Boards totally down.

- Skipper on trapeze and full cunningham > Raise the boards 6.0” up above the deck.



-Always raise the leeward board about 12.0” up above the deck and the weather board all the way leaving just enough board down to fill the trunk below the hull.

-Mast rotation always fully opened/released and enjoy the ride!



You turn the adjustable eye that is screwed into the lower rudder casting 1 Ό” out. You measure

between the black rudder case to the center of the adjustable eye.  This is a good starting point for most skippers.


Mast Set-up


With 175 lbs on board, recommend that you use 2 1/2” of spreader rake.

With 187 lbs on board, recommend that you use 2.0” of spreader rake.

With 198 lbs on board, recommend that you use 1 Ύ” of spreader rake.

With 210 lbs and above on board, recommend that you use 1 ½” of spreader rake.

Measure between the mast-track and diamond wires.  Place a sail batten from wire

to wire and measure the distance.  It is recommended not to use less than 1.0” spreader sweep.


Diamond tension:

To measure the tension of the diamond wires, use a Loose & Co tension gauge which

you put onto the wire and let go. (the expensive one with the two wheels)

This one gives you the most accurate readings. The numbers that work on this tension meter are:

32-36, until 15 knots

36-39, from 15 to 25 knots

39-42, from 25 plus

The carbon mast is very stiff sideways and flexible fore/aft.


Mast Rotation:

- Skipper sitting on the side= mast rotator pointing at middle of daggerboard case.

- Skipper hiking almost on trapeze= mast rotator pointing at end of daggerboard case.

- Skipper on trapeze= mast rotator pointing in the middle between rear beam and

daggerboard case.

- Skipper on trapeze and full cunningham= mast rotator pointing at intersection of

rear beam and outside of the hull.  Lighter skippers will not have this rotation so far back.  Move the rotation forward to open the top section of the sail.

Rig Set-up

The NACRA F17 seems to like a tight rig and the boat performs better with the tight shrouds.  Too tight and the mast won’t rotate downwind!

Mast Rake

Basic setting for now is the upper screw of the rudder spring on the transom.  Or with a rudder attached to the boat and in the kicked up position, 15-20” behind the transom measured on the top of the trailing edge.

To measure, you take your trapeze line and find the intersection of the front of the bridle tang and the hull.  You swing the trapeze line to the back and hold it against the transom or trailing edge of the rudder to see where it touches.


End pole: The end pole snuffer system, I found the sail to stay powered up by raising the spinnaker to full hoist and then using a 9”-12” pigtail at the tack.  The spin works best when grabbing the luff and rotating tightly to 90 degrees.  Always set your spin for a port rounding. 


Have a great sailing season!

Bob Curry

Team Nacra USA, F17 #723

Questios: see Ask Bob