When entering a strong thermal, you feel yourself swinging forward under your wing and being pulled up.
You must reduce you braking and give your wing speed during this phase. If you initiate a hard turn at this time, you risk a Spin (Recovery)…
Once installed in the thermal, reduce your speed but not more than minimum sink rate speed.
More important than using your wing’s best sink rate, you must concentrate on Centering the Thermal (using a Vario). When exiting a thermal, get ready to control the dive of your wing (ahead of you), by increasing the braking during the wing’s dive (release the brakes when the wing is at its most forward point)
If one follows the indications of his variometer : If it indicates an increase in the climb rate, open up your turn (you may even go straight). If the rate of climb diminishes, tighten your turn as we would otherwise be moving away from the center of the thermal.
There is no need to delay your response to your variometer, since it typically indicates the average over the last second of readings.
This technique is good for wide thermal lift without a sharp increase in climb rate at its center.
It can also serve to find better thermal cores when multiple thermals merge with altitude.
Photos
Source: Jérôme Daoust