  Longitudinal vector boson scattering provides an important probe of
electroweak symmetry breaking, bringing sensitivity to physics beyond the
Standard Model as well as constraining properties of the Higgs boson. It is a
difficult process to study due to the small production cross section and
challenging separation of the different polarization states. We study the
sensitivity to longitudinal $WV$ vector boson scattering at the high-luminosity
Large Hadron Collider in semileptonic final states. While these are
characterized by larger background contributions compared to fully leptonic
final states, they benefit from a higher signal cross section due to the
enhanced branching fraction. We determine the polarization through full
reconstruction of the event kinematics using the $W$ boson mass constraint and
through the use of jet substructure. We show that with these techniques
sensitivities around three standard deviations at the HL-LHC are achievable,
which makes this channel competitive with its fully leptonic counterparts.
