In ahoy writes:
On 23 Jul 2005 07:06:52 GMT, (Lauri Tarkkonen)
wrote:
In Larry writes:
"Robert or Karen Swarts" wrote in
:
Anyone care to discuss the relative reliability of
autopilots(electric/electronic) vs wind vanes for sail boats? Are wind
vanes still widely used?
BS
Lionheart, an Amel 41' ketch, is steered with a B&G Network Pilot electro-
hydraulic autopilot directly on the steering post under the aft cabin bed.
Its hydraulic cylinder is attached to the rudder post bellcrank with a
small ball joint, a miniature trailer hitch ball. Even if the entire
steering cable system fails (it looks like a heavy outboard flexible system
with dual enclosed flexcables), we can still steer the boat from the helm
or from the remote control box, providing there is DC power to run it. DC
power is two banks of L-16H 6V monsters. Power R' Us.
The only problem we've had with it is the chinzy way B&G attaches the
linear feedback sensor to the hydraulic cylinder, which comes loose
eventually and must be retightened and calibrated if you're not careful.
They buy this sensor from another manufacturer and don't seem to know how
to attach it to their cylinder, reliably.
As to operation, I have no trouble sleeping right on top of the running
hydraulic pump system, which only runs when the cylinder needs moving. You
can't hear it out of the aft cabin in the rest of the boat. From the
center cockpit, it's as if a ghost were at the helm...(c;
There are 3 modes....computer/chart plotter...or...its own compass
sensor...or...B&G Network Wind instrument on top of the mainmast, which
steers it on the wind like an extraordinary windvane would. All this is
selected from the Pilot's panel display, same size as the other B&G Network
sailing instruments in the helm's panel. It accepts NMEA0183 data very
well from our computer under The Cap'n nav software, either the RAymarine
RL70CRC radar/chart plotter, or the old Garmin 185 GPS/Chartplotter/Sonar
or from the Yeoman paper chart plotter's waypoints under our chart table
cover.
As with any autopilot, when the going gets rough, it's as useless as any of
them when it gets lost.....and you're left to steer by hand lock to lock
trying against hell to hold her on a course....with the wind sensor
spinning around crazy, the compass sensor being churned by being thrown
about and all the rudder in the world unable to steer the damned boat....
You cave the best argument for the windvane. The autopilots how
expensive one you ever buy, is for the fair weather. When the going gets
rough, the windvane will carry you trhough.
- Lauri Tarkkonen
I was looking at the Monitor windvane at a dock but I couldn't see the
whole thing. Does it have pully's to an inboard quadrant? Or does it
just move the little paddle aft of the rudder? Thanks and keep up the
good work.
Monitor is a servo-pendulum type (like Windpilot, Aries and some others)
windvane. The working principle is as follows: The wind tilts the vane
on one side or the other when the boat is not it the right direction of
the wind, the movement of the vane is only twisting the "padle" in the
water and when it is tvisted the boats movement throught the water will
push it to one side or anothe depending on the direction of the tilt of
the wane. The padle pulls the rope that pulls the tiller (or if you have
a steering wheel the rope is on a drum on the wheel and it rotates) and
it is then turning the boats rudder. So the steerin is not done by the
padle, it is only controlling the rudder.
Next time yuo are out boatin, take a padle or an oar and pull it through
the water with the side forward. It will go straight with very little
movement, if you twist it a bit you will find a very strong force
pulling it to the side. Imagine this fors applied to the rudder of the
boat. Notice that the power needed to twist the oar or paddle is very
minimal. But the power created by the paddle/oar is quite a big.
- Lauri Tarkkonen