1. Section 12, Tuning the Rig

2. Figure 12–1 Tuning the Rig Tuning the mast:
Adjusting the mast and standing rigging to enable proper adjustment of sails with running rigging. Mast must be in proper position intended by designer. Set mast perfectly vertical athwartships, checking with plumb bob.
Check balance while sailing. Correct excessive helm by adjusting jibstay/backstay. Raking forward reduces weather helm; tilting aft reduces lee helm. Remove/replace mast wedges during adjustment if mast goes through deck.
Check jib set under sail while close- hauled. If leech curls inward, tighten luff until curl just disappears. If curl persists, tighten jibstay, but not too tight. Simultaneous looseness in foot and leech indicates jibstay too tight. Check speed with accurate knotmeter, loosen jibstay one turn and recheck. Too tight a jibstay will cause speed to drop. Check for slight weather helm, adjusting rake as required.
At dock adjust shrouds if necessary to be sure mast is vertical athwartship. Adjust uppers first, then lowers. Use steel tape measure attached to halyard to measure, adjusting as required to make port and starboard equal. Use cotter pins in turnbuckles and tape over.
While sailing check that mast is straight on all points of sail.
Figure 12–1 Tuning the Rig

3. Explain the purpose of a jumper strut/stay.
Figure 12–2 Jumper Struts

4. Describe the process of shroud adjustment to be sure the mast is vertical athwartship.
Explain how to determine when the tension in the shrouds is about right.
List the steps in tuning the rigging of a boat with multiple spreaders.
Figure 12–3 Turnbuckle

5. Vocabulary
Cotter Pin. A split pin, the ends of which are bent after insertion through a hole.
Jumper Strut. Horizontal spar on the forward side of the mast to which the jumper stay is attached to keep the upper part of the mast straight.
Toggle. A U-shaped fitting linking a turnbuckle with a chainplate; it permits movement so the turnbuckle is not bent when the stay is pulled out of line.
Turnbuckle. A tension-adjusting device for tightening wire rigging or cable, composed of threaded rods inside a threaded barrel.

6. Supplemental Illustrations for Section 12, Tuning the Rig

7. MEASURE TO EACH SIDE TO SEE IF MAST STEP IS CENTERED.
USE HALYARD AND RULER ON EACH GUNWALE TO SEE IF TOP IS CENTERED.
TIGHTEN SHROUDS AND STAYS.
SIGHT UP MAST TO SEE IF MAST IS STRAIGHT. ADJUST SHROUDS AND STAYS AS NECESSARY TO STRAIGHTEN.
REPEAT UNDERWAY AND READJUST AS NECESSARY.

8. End of Section 12 Slides