Several photographs of the ferries show a signal was carried on the mast. The purpose of this
signal Three Vertical Balls has proved difficult to determine.
Assistance was sought from various forums dealing with shipping and the following explanations were offered:-
- indicates a vessel navigating stern foremost
- it should signify a vessel aground in or near a fairway.
- Rule 11 paragraph (e) three black balls in a vertical line, ship aground.
- usually indicated on restricted waters a cross trade (Ferry?), so the three balls maybe is the
daylight signal according to local pilotage laws?
- Rule 4. A vessel engaged in laying or picking up cable or a
navigation mark, surveying or underwater operations, or a vessel
engaged in replenishment at sea or in the launching or recovery of
aircraft carries, in lieu of her steaming lights, two all-round red
lights with an all round white light between them, each visible at least two miles.
Perhaps an adaptation of this, the vessel in question having limited ability to manoeuvre.
However the most likely explanation comes from Ian Campbell who
helped with the explanation on how to identify individual each ferry. Ian advises :-
"The 3-ball signal doesn't
exist in current "Collision Regulations", but I was told
they indicated that the ferries would give way to river traffic in
both directions. Otherwise, for example, a westbound tanker going
to Grangemouth would have to give way to a northbound ferry. And
that fits with the fact that the balls were removed for travel to
and from Leith for annual overhaul. Incidentally, Dundee never
carried these 3 balls, but perhaps that was just because it had no
The possibility that the balls indicated navigating in
reverse (not true). So far as their appearance was concerned,
northbound ferries were not in reverse. They had double sets of
navigation lights which were switched over for each direction, and
for daylight journeys there were both green and red panels on each
end of the bridge. Again, Dundee was the exception, but it turned
round for the northbound journey."