J105 Owner Manual 2012.pdf - J/Owners

J/105 Owner Guide ...................................................................................................................................................................................................................................................... 14
Tuning the J/105 Rig
Following is a general guide to tuning your J/105 mast. Please consult your sailmaker for “fine-­tuning”
the mast to match the sails.
With the standard length J/105 headstay and the mast step situated in the middle, the mast rake
(as measured from the back of the mast at deck level to a plumb on the main halyard) should be
approximately 30 inches. Several owners have opted to install an additional toggle at the top of
the headstay, and then shorten the drum turnbuckle so to lower the drum as close as possible to
the deck. According to J/105 Class Rule 7.4 “the headstay system length, measured between the
centerline of the headstay pin on the mast to the intersection of the stem line and the sheer line
at the bow, shall not be greater than 13035mm nor less than 12985mm. We recommend the
maximum allowed headstay length for most conditions.
The upper shrouds are attached to the outer chainplate hole. The lowers are connected to the
inner hole. The intermediates are secured in the forward hole. Begin by hand tightening the
shrouds, being careful to keep the mast centered aloft. Check alignment by hoisting a tape
measure up the main halyard and comparing measurements to the port and starboard
chainplates. When the top of the mast is centered, sight up the mast track to check for alignment
of the lower part of the mast. Hand adjust the shrouds as necessary to center the mast.
After the rig is centered and hand tight, we recommend additionally tightening the shrouds the
following number of turns:
Upper Shrouds: +11 turns
Lower Shrouds: + 2 turns
Intermediates:
+ 8 turns
You’ll find it easiest to tighten the upper shrouds if you pump the backstay down 2-­‐3 inches first
to relieve load. Under sail, it is easiest to adjust only the leeward shrouds, then tack to adjust the
other side.
Once you have initially tuned your J/105, then go sailing in a brisk breeze, spending equal time
on both tacks. Even though rod rigging is the lowest stretch material possible, you’ll still see a
little loosening after the initial breaking in period. Be sure to sight up the mast while it is under
load to see if it remains in column.