Hello Jeff. Here is what Wikipedia said:
rowlock[1] UK:
/ˈrɒlək/, sometimes
spur (due to the similarity in shape and size),
oarlock (USA)
[2] or
gate (Australia) is a brace that attaches an
oar to a
boat. When a boat is rowed, the rowlock acts as a
fulcrum, and, in doing so, the propulsive force that the rower exerts on the water with the oar is transferred to the boat by the thrust force exerted on the rowlock.
On ordinary rowing craft, the rowlocks are attached to the
gunwales. In the sport of
rowing, the rowlocks are attached to
outriggers (often just called "riggers"), which project from the boat and provide greater leverage. In sport rowing, the rowlocks are normally U-shaped and attached to a vertical pin which allows the rowlock to pivot around the pin during the rowing stroke. They additionally have a locking mechanism (properly known as "the gate") across the top of the "U" to prevent the oar from unintentionally popping out of the rowlock.
Originally, rowlocks were two wooden posts or
thole pins that the shaft of the oar nestled between. Single THOLE PINS may be used when the oars have holes cut into the loom which then sits over/around the THOLE PIN. (Captain Dennis Robinson FNI, Master Mariner)
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hope this will help.