  The Georgi-Machacek (GM) model is used to motivate and interpret LHC searches
for doubly charged scalars decaying to vector bosons pairs. The doubly charged
scalars are part of a degenerate fermiophobic custodial fiveplet with states
$H_5^{\pm\pm}$, $H_5^\pm$, and $H_5^0$ and common mass $m_5$. The GM model has
been extensively studied at the LHC for $m_5 > 200$ GeV but there is a largely
unprobed region of parameter space from $120$ GeV $< m_5 < 200$ GeV where light
doubly-charged scalars could exist. This region has been neglected by
experimental searches due in part to the lack of a benchmark for $m_5 < 200$
GeV. In this paper we propose a new "low-$m_5$" benchmark for the GM model,
defined for $m_5 \in (50, 550)$ GeV, and characterize its properties. We apply
all existing experimental constraints and summarize the phenomenology of the
surviving parameter space. We show that the benchmark populates almost the
entirety of the relevant allowed parameter plane for $m_5$ below 200 GeV and
satisfies the constraints from the 125 GeV Higgs boson signal strengths. We
compute the 125 GeV Higgs boson's couplings to fermion and vector boson pairs
and show that they are always enhanced in the benchmark relative to those in
the Standard Model. We also compute the most relevant production cross sections
for $H_5$ at the LHC, including Drell-Yan production of $H_5$ pairs. The
process $pp \to H \to H_5 H_5$ contributes in a small region of parameter
space, but is small compared to the Drell-Yan production cross section. Finally
we compute the branching ratios of $H_5^0 \to \gamma\gamma$ and $H_5^{\pm} \to
W^{\pm} \gamma$. The width-to-mass ratio of each of the $H_5$ states is below
1\% over the entire benchmark, so that the narrow-width approximation is well
justified.
