  A simple way to couple an interface dynamo model to a fast tachocline model
is presented, under the assumption that the dynamo saturation is due to a
quadratic process and that the effect of finite shear layer thickness on the
dynamo wave frequency is analoguous to the effect of finite water depth on
surface gravity waves. The model contains one free parameter which is fixed by
the requirement that a solution should reproduce the helioseismically
determined thickness of the tachocline. In this case it is found that, in
addition to this solution, another steady solution exists, characterized by a
four times thicker tachocline and 4-5 times weaker magnetic fields. It is
tempting to relate the existence of this second solution to the occurrence of
grand minima in solar activity.
