The leeboard is a necessary attachment to the sailing outfit.
In rough water a centreboard must strain a boat more than a leeboard does.
With this arrangement the leeboard could be raised and lowered and also shifted to the lee side on each tack.
The pleasure of sailing was thus denied to me for several years afterwards, and all through my ignorance of the leeboard.
The leeboard, like a centre board, is of course intended to keep the canoe from sliding off when trying to beat up into the wind.