The Jefa rack and pinion system should always be
delivered with the stopring. The stopring will prevent the output lever
from going over the dead point. If this happens, the yacht will not be
able to steer any more with all due consequences. The stopring will
prevent the steering pedestal from damage, but when no rudder stops are
fitted, all forces will have to go through the draglink and in the event of a collision, the draglink could get damaged. Fitting rudder
stops in combination with the stop plate will protect both the pedestal
and the rudder.
As the output lever and the tiller lever are not pointing 90° starboard
or port when the rudder is midships it is important to understand about
the offset angles used with the rack and pinion system. The rack and
pinion systems uses a principal known as "wide angle geometry"
which gives very direct steering near midships and an increasing
mechanical advantage (reduction) as the rudder approaches full travel.
This results in the most direct, positive system available to a
helmsman.
To accomplish this effect the pedestal output lever is shorter than the
tiller lever in a ratio of 1.54:1. At midships therefore the tiller arm
and output lever are not pointing 90 degrees sideways, but instead are
angled slightly forward. This offset angle is known as B° and varies
dependent on the distance between the pedestal and the rudderstock. The
shorter the distance the greater the offset angle B. (Please click on the picture for a
larger view)
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