J/Boats J/88, Owner'S Manual

Page: 16 / 58

J88 OWNER MANUAL 16
Tuning the Rig
Tuning the Mast
Following is a general guide to tuning your J/88 mast. Please consult your sailmaker for “fine-tuning” the mast
to match the sails in varying wind conditions.
BEFORE YOU BEGIN INSURE THE MAST THROUGH BOLT IS PROPERLY INSTALLED TO PREVENT
THE MAST FROM JUMPING OFF THE MAST STEP.
With the standard length J/88 headstay (turnbuckle ½ open) the mast rake as measured from the back of the
mast at deck level to a plumb on the main halyard should be approximately 12-14 inches.
For shroud location the “Uppers” (V1) are attached to the aft outside chainplate hole, the “Lowers” (D1s) are
connected to the hole on the portion of the chainplate that angles inboard. The “Intermediates” (D2s) are
positioned in the forward location at each lower spreader and attach to the forward outboard position on each
chainplate.
Begin by hand tightening the upper 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. Adjust the shrouds as necessary to center the mast.
After the rig is centered and hand tight, we recommend additionally tightening the shrouds. Here is a good
conservatively tight all-purpose setting based on the initial J/88 sea trials as measured with a PT2 Loos Gauge.
Shroud Wire Load Loos Gauge
Uppers (V1) 6mm 1850 lb. 40
Lowers (D1) 6mm 860 lb. 33
Intermediates (D2) 5mm 229 lb. 17
Typically the Intermediates should remain loose until the Uppers and Lowers are close to their intended
tensions. Thereafter the Intermediates can be taken up to hand tight and adjusted after going sailing and
checking the mast on both tacks for straightness.
You’ll find it easiest to tighten the Upper shrouds if you apply some backstay tension first to bend the mast and
thereby reduce load. Under sail, it is easiest to adjust the leeward shrouds, then tack to adjust the other side.
The shroud turnbuckles are best adjusted with a crescent wrench and strong screw driver. It is also a good idea
to use grease on the threads of the turnbuckles to help reduce friction as the loads increase.
Once you have initially tuned your J/88, go sailing in a brisk breeze, spending equal time on both tacks. Even
though compacted strand wire rigging is a low stretch material, 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 confirm that the mast remains in
column. Make the appropriate adjustments as necessary.
A note about the standard Dyneema backstay. When reaching and running you may notice a vibration sound
that can take place due to the larger relative diameter of the backstay vs. wire. There are some tricks to making
this go away like wrapping shock cord up the backstay about 2’ or so like a hockey stick grip. This harmonic
typically only happens in some decent breeze (15 knots or so) and is considered normal.