  We present a preliminary computation of potentials between two static quarks
in $n_f=2$ QCD with O(a) improved Wilson fermions. We explore different
smearing choices (HYP, HYP2 and APE) and their effect on the signal to noise
ratio in the computed static potentials. This is a part of a larger effort
concerning, at first, a precise computation of the QCD string breaking
parameters and their subsequent utilization for the recent approach based on
Born-Oppenheimer approximation (Bicudo et al. 2020 \cite{Bicudo:2019ymo}) to
study quarkonium resonances and bound states.
