Years of sailing with winches large enough to pull 2+ tons taught me a
few lessons about self tailing and hand tailing. Fortunately my or
others screw ups resulted only in flailing sails, not the disaster that
can happen with heavy vertical lifting. Although an out of control boom
can be a lethal device as a friend was killed by one.
I would never use a self tailing winch for overhead lifting. While the
grip systems usually work, "usually" is not safe enough. They are also
sensitive to the size, type of line and its condition. Then the release
from the self tailing mechanism requires actions which often cause a
jump in the load part of the line. The person releasing the line is in
an awkward position to control the line and has fingers close to the drum.
The person doing hand tailing needs to be thoughtful, alert,
communicative, physically capable, and trained. Just as any other
ground crew member. The functional problems I encountered with sailing
winches were overruns, jams, and run-offs. An overrun is when a line
gets under a turn nearer to the load (basically a half hitch knot).
These can be very hard to safely or slightly release. A jam can happen
when the turns get so tight together (or too many turns on the drum)
they need hand massaging or a turn unwound to release and slip.
Run-offs are when loops slip off the open end of the capstan and the
tailing load jumps or becomes the total load. These are sometimes
caused by the line handler not paying attention to the angle of the free
line to the capstan, or jumps in the load.
Is a spool drum winch better? - it depends. Different kinds of jams
occur for winches of the type used on vehicles and tractors (experience
with this), which btw are not overhead load rated. A crane winch spools
wire rope with perfect lays to not have those problems. Like my
HDX589's feeder to the spool. However, working with wire rope has a lot
of downsides for handling and rigging. Not the way to go IMO for
amateur radio sized towers and loads especially with the rope technology
now available.
The pro team that did my big tower used ropes and a capstan with power
up/down. That capability with a good operator avoids the problems
mentioned with lines on capstans. The loads were up to 350# antennas
and controllable in less than a inch up/down. A convenient tie off on a
cleat was on the winch mount and that was backed by a safety tie off.
The tower sections weighed up to 1000# and went up with a crane.
Although they had the gin pole and winch capacity for them the crane was
faster, cheaper, and safer. For more than 25G towers and bigger than
tribanders, I think these are the ways to go.
Grant KZ1W
On 9/12/2017 19:23 PM, Richard (Rick) Karlquist wrote:
I have been reading about how nice capstan winches are,
but I have no experience with them. They seem very
dangerous since the line comes loose and the load
falls down in case the line handler's attention wanders
for a second. It seems especially dangerous to be
lowering a heavy load when the handler has to pay
out the line just fast enough, but not too fast.
A foot switch is suggested, but it doesn't work as
a dead man safety. The winch stops but the line
still slips if not held back.
Seems like an accident waiting to happen, like free
climbing a tower. Can someone with experience explain
how these capstans could possibly be safe?
Rick N6RK
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