Actually, they have no effect on stability, given by the hull shape.
leeboards prevent drift to leeward as there is no sharp keel.
when you tack, you raise the one that was on the lee side, and lower the other one
Ditto, lee boards are a dagger board, center board or modern keel, device to allow the vessel to sail, with minimal drift to lee. Deployed on the leeward side, in a run not needed as there no side directional shift.
Hallo @AlgirdasHello dear colleagues. I'm a beginner modeller, I've only been building wooden ship models for about 4 years (when I have time) and I want to ask you WHAT IS THE PURPOSE OF THIS PART ON THE SHIP?