Self Steering / Windvanes
Posted: Tue Jan 06, 2009 10:42 pmFrom: Paulus (Original Message) Sent: 12/6/2007 9:42 PM
Does have anyone experience with selfsteering devices such as a windvane? Can you build it your self and what is the principle based on?
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Recommend Message 2 of 3 in Discussion
From: Keitherson Sent: 12/7/2007 10:33 AM
Hi
There are 3 main ways to go with self steering
1/ an electronic tiller pilot - easy and accurate. About $700 -$1000
for a Top Hat. It uses a bit of power so you need a way to keep your
batteries charged
2/ Sheet to tiller steering - this uses the power of the wind taken
directly from the pressure on the mainsheet or sometimes the jib sheet
, a bit complex and you need to have the boat well balanced, but very
cheap, about $50 in rubber shock cord and rope.
3/ A Windvane - The principle is a complex subject but I will have a go
at a brief overview:
There are two main parts to a windvane steering system. The wind vane
and the water vane which is usually referred to as the oar. The wind
vane can either rotate about a vertical or horizontal axis. As the
force from the wind is small on vertical axis vanes they are usually
only used on Trim Tab designs where the wind vane directly turns a trim
tab on the rudder. These designs are simple and cheap to build, the
famous yachtsman Bernard Moitessier sailed one and a half time around
the world non stop using a simple trim tab vane that he built with a
broom stick and water pipe. Unfortunately they are only practical on
boats with rudders hung on the transom so no good for a Top Hat.
Most wind vanes these days are servo designs where the wind vane turns
the oar which turns the tiller by means of ropes. The oar turns on a
vertical axis and the main problem is that the pressure transmitted by
the wind in normal sailing conditions is very small so if this rotation
is directly linked to the tiller, the vane can easily be over powered
by bad sail trim or wave action. To overcome this, most modern designs
use an oar, that not only rotates on a vertical axis but is also
allowed to rotate on a horizontal axis AT THE SAME TIME. In other words
the wind vane twists the oar out of alignment with the water flow and
the oar is pushed sideways very powerfully by the water. The sideways
movement is linked to the tiller by ropes. The side to side action of
the oar, or pendulum action, gives these designs the name "pendulum"
and the fact that they are linked to the main rudder gives them the
name "servo" Most commercial designs these days are Servo Pendulum but
where it is difficult to link the wind vane to the tiller such as
centre cockpit yachts a wind vane may have it's own separate rudder,
in which case it would be a Pendulum Servo Auxiliary Rudder System.
With pendulum servo designs the requirement to have an oar rotating on
two axis at the same time is what makes the design complex and
expensive. However, if you wanted to experiment you could build one for
less than $100. The late Walt Murray provided plans for these which are
built out of PVC pipe.
http://www.mindspring.com/~waltmur/Self-Steering/. Also if you want to
experiment with sheet to tiller steering this is a good site
http://www.solopublications.com/sailariq.htm#main
On my Top Hat I have an outboard mounted in a cut out in the transom so
I can't easily mount a wind vane on the centreline of the boat so I
bought a Raymarine ST 2000 electronic tiler pilot which works well in
the harbour but can have problems outside in large waves. Also in
addition to the main battery and solar panel I have a smaller battery
with it's own solar panel so I don't get caught without power for the
radio and nav lights.
Keith
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Recommend Message 3 of 3 in Discussion
From: Paulus Sent: 12/8/2007 1:30 AM
Hi Keith,
Thank you for the detailed description. I've looked at Walt Murray's website and I'll give it a go. It doesnot look too complex and I'll post my experiences on the user forum.
Cheers, Paul
Does have anyone experience with selfsteering devices such as a windvane? Can you build it your self and what is the principle based on?
-------------------------------------------------------------
Reply
Recommend Message 2 of 3 in Discussion
From: Keitherson Sent: 12/7/2007 10:33 AM
Hi
There are 3 main ways to go with self steering
1/ an electronic tiller pilot - easy and accurate. About $700 -$1000
for a Top Hat. It uses a bit of power so you need a way to keep your
batteries charged
2/ Sheet to tiller steering - this uses the power of the wind taken
directly from the pressure on the mainsheet or sometimes the jib sheet
, a bit complex and you need to have the boat well balanced, but very
cheap, about $50 in rubber shock cord and rope.
3/ A Windvane - The principle is a complex subject but I will have a go
at a brief overview:
There are two main parts to a windvane steering system. The wind vane
and the water vane which is usually referred to as the oar. The wind
vane can either rotate about a vertical or horizontal axis. As the
force from the wind is small on vertical axis vanes they are usually
only used on Trim Tab designs where the wind vane directly turns a trim
tab on the rudder. These designs are simple and cheap to build, the
famous yachtsman Bernard Moitessier sailed one and a half time around
the world non stop using a simple trim tab vane that he built with a
broom stick and water pipe. Unfortunately they are only practical on
boats with rudders hung on the transom so no good for a Top Hat.
Most wind vanes these days are servo designs where the wind vane turns
the oar which turns the tiller by means of ropes. The oar turns on a
vertical axis and the main problem is that the pressure transmitted by
the wind in normal sailing conditions is very small so if this rotation
is directly linked to the tiller, the vane can easily be over powered
by bad sail trim or wave action. To overcome this, most modern designs
use an oar, that not only rotates on a vertical axis but is also
allowed to rotate on a horizontal axis AT THE SAME TIME. In other words
the wind vane twists the oar out of alignment with the water flow and
the oar is pushed sideways very powerfully by the water. The sideways
movement is linked to the tiller by ropes. The side to side action of
the oar, or pendulum action, gives these designs the name "pendulum"
and the fact that they are linked to the main rudder gives them the
name "servo" Most commercial designs these days are Servo Pendulum but
where it is difficult to link the wind vane to the tiller such as
centre cockpit yachts a wind vane may have it's own separate rudder,
in which case it would be a Pendulum Servo Auxiliary Rudder System.
With pendulum servo designs the requirement to have an oar rotating on
two axis at the same time is what makes the design complex and
expensive. However, if you wanted to experiment you could build one for
less than $100. The late Walt Murray provided plans for these which are
built out of PVC pipe.
http://www.mindspring.com/~waltmur/Self-Steering/. Also if you want to
experiment with sheet to tiller steering this is a good site
http://www.solopublications.com/sailariq.htm#main
On my Top Hat I have an outboard mounted in a cut out in the transom so
I can't easily mount a wind vane on the centreline of the boat so I
bought a Raymarine ST 2000 electronic tiler pilot which works well in
the harbour but can have problems outside in large waves. Also in
addition to the main battery and solar panel I have a smaller battery
with it's own solar panel so I don't get caught without power for the
radio and nav lights.
Keith
----------------------------------------------------------------
Reply
Recommend Message 3 of 3 in Discussion
From: Paulus Sent: 12/8/2007 1:30 AM
Hi Keith,
Thank you for the detailed description. I've looked at Walt Murray's website and I'll give it a go. It doesnot look too complex and I'll post my experiences on the user forum.
Cheers, Paul