Horizontal dipoles not only need no ground plane but become "sky
warmers" if mounted close to one. OTOH, single-element verticals need a
good ground plane to supply the missing half of the dipole. From what
I've seen here so far, most boat antennae, including Uncle Sam's, are
hybrids; neither vertical nor horizontal, some dipoles some not. So it
could be that you're *all* right, depending on the particulars of the
antennae you've seen. Sort of like blind guys describing an elephant
based on touch.

When we used to camp alot I'd put up a 1/4 wave vertical cut for 20
meters (32') with a lanyard that let me hoist an inverted V cut for 40
to the top of it. With one or the other (I'd lower the V for 20m) fed by
an auto tuner my child bride could work most anywhere on her 100w ICOM
706. Need Samoa? Switch on the 1.5KW amplifier.

Given the excellent groundplane our boat sits in I'd think that a 32'
vertical with top loading for lower freq's mounted on the stern pulpit
with a ground wire and sinker tossed off the fantail otta work FB. For
those who prefer complication the fore and aft stays otta make a great
inverted V if suitably insulated. Natch YMMV.

73, K3DWW