  A search for a new heavy particle decaying to a pair of vector bosons (WW or
WZ) is presented using data from the CMS detector corresponding to an
integrated luminosity of 35.9 fb$^{-1}$ collected in proton-proton collisions
at a centre-of-mass energy of 13 TeV in 2016. One of the bosons is required to
be a W boson decaying to e$\nu$ or $\mu\nu$, while the other boson is required
to be reconstructed as a single massive jet with substructure compatible with
that of a highly-energetic quark pair from a W or Z boson decay. The search is
performed in the resonance mass range between 1.0 and 4.5 TeV. The largest
deviation from the background-only hypothesis is observed for a mass near 1.4
TeV and corresponds to a local significance of 2.5 standard deviations. The
result is interpreted as an upper bound on the resonance production cross
section. Comparing the excluded cross section values and the expectations from
theoretical calculations in the bulk graviton and heavy vector triplet models,
spin-2 WW resonances with mass smaller than 1.07 TeV and spin-1 WZ resonances
lighter than 3.05 TeV, respectively, are excluded at 95% confidence level.
