Hub ↑

Sail trim

Pick a course, then shape the sail with the lines. The speed tells you what is working.

From the side. Red telltales are on the outside of the jib, green on the inside. On this tack the outside is the port side, so the colours match the navigation lights.
From above. The sail drawn at three heights: foot, middle and top. The gap between them is twist.
Course
Wind

Picks Light, Medium or Strong from the wind on the Bay now.

Upwind

0.0 knots

Heel 0°
Depth
–
Draft
–
Twist
–
pulled inlet out
hard onoff
pulled inlet out
aftforward
tighteased
hard onoff

The fast settings for all three courses, at this level and wind.

Wind ranges are the true wind. Speeds are teaching figures for a small dinghy, not data for any class. In the view from above, the wind comes from the right.

The names

The sail

Head
The top corner.
Tack
The front bottom corner, at the mast or the bow.
Clew
The back bottom corner, where the sheet or outhaul pulls.
Luff
The front edge. The wind meets the sail here.
Leech
The back edge. The wind leaves the sail here.
Foot
The bottom edge.
Battens
Stiff strips in pockets that hold the leech in shape.

The rig

Mast
Holds the luff of the mainsail.
Boom
Holds the foot of the mainsail.
Forestay
The wire from the bow to the mast. The jib’s luff runs along it.
Jib
The small sail in front of the mast.

The lines

Mainsheet
Sets the angle of the mainsail. Upwind it also pulls the leech tight.
Vang
Holds the boom down and the leech tight, most of all when the sheet is eased. Also called the kicker. A gnav does the same job, pushing down from above the boom.
Jib sheet
Sets the angle of the jib.
Jib car
The sliding lead for the jib sheet. Forward closes the jib’s leech; aft opens it.
Outhaul
Pulls the clew along the boom. Tight makes the lower sail flat; eased makes it full.
Cunningham
Pulls the luff down near the tack. It moves the draft forward and opens the top of the sail.

Reading the sail

Telltales
Wool or ribbon on the sail. Both sides streaming means the wind is flowing well. Here red is on the outside of the jib and green on the inside, matching port and starboard on this tack.
Luffing
The front of the sail lifts or flaps. The sail is out too far.
Stalled
The flow has broken away from the back of the sail. It is pulled in too far.
Depth
How full the sail is. Full is powerful; flat is fast in a breeze.
Draft
Where the deepest part of the sail sits, front to back.
Twist
How much more open the top of the sail is than the foot.
Slot
The gap between the jib’s leech and the mainsail.