01Headsail luff
Headsail threads sit in pairs near the luff, one on each side. Windward faces the wind; leeward faces away. They swap sides when the wind changes sides.
A LITTLE TOOL FOR A BETTER FEEL FOR SAILING
Read the wind. Find your trim.
Drag the wind arrow. Watch the sails change and get trim advice for your wind.
WIND & SAILS
Drag the wind arrow around the boatYou can also use the arrow keys.
Drag the wind around the boat. You can also use the arrow keys.
POINT OF SAIL IN THE MODEL
m/s
018 m/s
Moderate windThe wind you feel aboard
Boat & displaySloop · 2 sails
Choose a boat
One mast, a mainsail and a jib.
LET THE AIR SHOW YOU
Read the wind with telltales
On the boat right nowThe threads follow the flow
With the guide’s automatic basic trim, the threads illustrate smooth flow along the sail. On a real boat, you read the threads and make the adjustments.
Learn to read the telltalesCompare balanced, undertrimmed and overtrimmed sails
Small threads make airflow visible. Compare three simple headsail settings and see how to adjust the sheet.
PRACTICE · UPWIND ON A FIXED COURSE
Same heading and wind in all three examples. Here we change only the headsail sheet.
Airflow toward the leech
Both threads follow the sail
Threads on both sides point towards the sail’s trailing edge. This is a useful basic setting to start from.
1
WindwardStreaming aftSolid telltale · windward side
2
LeewardStreaming aftDashed telltale · leeward side, seen through the sail
What to adjustKeep the sheet setting and watch boat speed and balance.
The examples only change the practice illustration and are independent of the boat’s automatic basic trim.
02Mainsail leech
The mainsail telltale sits on its trailing edge. It should generally flow out behind the sail. If it stays hidden behind the cloth, the top may be too closed: ease the sheet to open the leech and check again.
The boat’s threads illustrate basic trim. The examples apply with wind forward of the beam; they are not a universal rule in a wind shadow or deep downwind. Also read boat speed, heel and helm pressure.
Understand the trimThe why, what to look for, and what to adjust
A smaller wind angle calls for closer trim. If the boat loses speed, slightly easier can help the airflow recover.
are small threads that show airflow. Look for them streaming aft along the sail.
The controls depth in the lower . affects the position of that depth. The affects . Make one small adjustment at a time and feel how the boat responds.
YOUR BOAT. YOUR WAY TO LEARN.
One mast, a mainsail and a jib.