Johnhh wrote:

Thanks David,
my information on the "feel at the wheel" came from a Raymarine rep. and
Simrad documentation. I have no first hand knowledge, but suspect it is a
fairly minor difference. snip

The comment about hydraulic systems having less feel may have been in
reference to a hydraulic primary or hand steering system as compared to
a mechanical hand steering system.

In a hydraulic steering system the helm is mounted on the shaft of a
pump or directly coupled to a pump with a loop of chain. That is a
closed loop system with a cylinder that pushes or pulls (depending on
which way the helm/pump is turned) on an arm on the top of the rudder
post.

The "feel" of helm movements is lost in the high mechanical advantage of
a hydraulic system. It can be rendered further imprecise by factors
such as the presence of any pockets of air trapped in the system and any
weep against pressure that occurs in the pump or cylinder.

Properly installed and maintained, a hydraulic hand steering provides
very little or no feedback at the hand to turning forces. It feels like
power steering did on older (1960's or so) American cars, no change in
turning forces from lock to lock. Newer cars have variable ratio power
steering that gives an impression of feedback with turning forces that
increase as you get further away from the neutral position.

If you have ever steered a boat with hydraulic steering that is badly
worn or has pockets of air in the steering loop, you'll never forget it.

Your autopilot, hydraulic or electric, is trying to maintain a heading
and will normally push and pull the same arm on the rudder post that
your manual steering does.

If a linear drive has any clutch slippage or hydraulic weepage the
course computer will make frequent to nearly continuous steering inputs.
The rudder wants to fall back to center and the AP keeps working to
steer to the set heading. If that happens you'll see it on an ammeter
as David describes.

Jack

--
Jack Erbes in Ellsworth, Maine, USA - jackerbes at adelphia dot net
(also receiving email at jacker at midmaine.com)