Top left: Spooned keyways are designed to distribute loads
and minimize stress risers. Left: The burnishing indicates that
this propeller shaft taper has been lapped. Lapping provides
a customized fit between a propeller or coupling and shaft.
Above: Chris Brown holds cutless bearing mandrels used to
support bearings while they are machined.
STRAIGHT LINE DOES NOT LIVE BY
ALIGNMENT ALONE
At this point, you might believe that all Straight Line
does is check shaft alignment, and you’d be forgiven for
coming to this conclusion because I’ve yet to mention
their other specialties. In additional to carrying out
alignments, the folks at Straight Line also remove,
install, and lap props; repair and replace stabilizer
fin bearings and seals; replace and balance motor
mounts (did you know motor mount loads need to be
balanced?); and install and service torsional dampeners.
In addition to their crack optical alignment crew,
Straight Line has an equally crack machine shop
crew. These two aspects of the program are more
than symbiotic; one cannot survive without the other.
No matter how well aligned a shaft may be with its
bearings, if the manner in which the shaft mates to
the engine is flawed in any way, the shaft and engine
as a unit will not yield the ultra-precision that is
necessary and the standard for Straight Line. Toward
that end, the machine shop’s repertoire includes shaft
straightening for those up to 6 inches diameter and 35
feet long; coupling repair and fabrication; cutting of
shaft tapers, coupling bores, and keyways (keyways cut
by Straight Line on all shafts over 2 inches include a
stress dissipating “spoon” design); coupling pilot repair
and replacement (this is an often overlooked aspect
of alignment, the fit of the shaft coupling’s recess to
the transmission coupling’s protrusion); and strut and
rudder repair.
DETAILS, DETAILS
A few of the small, yet valuable, touches I noted
while poking around the shop spoke volumes about
