Date: 25 May 2015. Inexpensive Line Cutter.
Richard on M/V Dauntless posted to
his website about the niftiest item, and I want one. All of us on
boats without line-cutters on our shafts worry that the rope from a
crab trap will ensnarl our propeller. That's bad. It can be very bad if
the rope manages to loosen the shaft from the coupler at the
A coupler is a piece of metal that
holds the shaft to the transmission so when the boat is in gear the
shaft will turn. The problem develops when a line gets caught in the
propeller. It can exert force and potentially dislodge the shaft
from the transmission.
Basically the line can pull the shaft
out from the transmission. Were that to happen the boat will
not move. Water could also come into the boat and that's not good
either! Worse case scenario, the boat might sink.
Coupler, Keyway and
Key plus Zincs
Coupler connects the aft end of the transmission to the
shaft. It either slides on (one piece) or is a "split ring"
meaning there are two portions that bolt together around the
Next, moving toward the
back of the boat is a blue arrow. That points to the
Key. The Key is a square piece of
stainless (or bronze) and it fits into the Keyway.
Aboard Seaweed, my key is 3.25" long and 5/16"
All that is just fancy
Boat Talk. A
keyway is simply a slot the square key fits into. It locks the
coupler and the shaft together so they spin at the same time.
There is a notch in the coupler and an equally deep one in the
shaft. The key fits in that slot.
Aft of there are two
zincs. Zincs are used to protect
the metal in the boat from stray current (electricity). It's a
part of the bonding system, which is not the focus of this
article. We'll cover that later.
electricity and zincs protect against electrolysis. The
bonding system is what keeps electrolysis from damaging our
I keep my spare zincs fastened on the propeller shaft inside my hull.
close to the stuffing box. The black rubber with stainless bands
is a stuffing box. And no, of course it is not square. This is a
boat, where the head is a place you put your butt! I don't try
to understand it.
The "real" zinc anodes are in the water. These two
are still useful and I recommend every boater keep their spares
inside and attached to the shaft. The reason to have bolted on zincs
inside the boat is to prevent the shaft from coming out.
If there were a catastrophe such as a line being
caught in my prop, those two should keep the shaft in the
boat. A shaft falling out (and it has happened to others)
generally sinks the boat.
Also, having spares inside
means should I need to replace a zinc anode at any time, I've
got one (or two) ready. And I can find them.
Keeping rope from wrapping around the shaft/propeller is a Good
Idea. Unfortunately all too often when the words Good Idea are
applied in a "marine application" the costs skyrocket. Fortunately
Captain Richard discovered SALCA.
aka Sacrificial Anode
Same link made smaller:
The ZincWarehouse.com SALCA page
Dauntless said "The one on the
shaft is a combination steel cutter attached to a clamp on zinc
anode. It costs only $60. Itís the second one Iíve put on and it
works wonderfully. Half eaten, it tells me itís doing its job and no
pieces of line wrapped around the shaft as had happened in the
This is his old SALCA at haul out,
prior to replacement with a new one:
Available at the
Warehouse, it's something you should consider if you don't have
a line cutter already. I know I intend to order one next week. This
is a Good Idea, and relatively inexpensive. I know it's a lot
cheaper than hiring a diver to remove a line wrapped around the
In looking at the unit, it appears
that the blade (split into two pieces) could be attached to a donut
shaped anode after the initial one needs replacement. It's stainless so I
suspect that by drilling holes through a donut zinc I could
through-bolt the blade pieces to a new zinc with relative ease. I'll
test that theory later.
Have you a SALCA or a standard line cutter on your
Are you glad you have it or was the unit a waste of money?
In the Bilges,
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