Vane Self Steering Gear


Our Hasler self steering gear was bought second hand. Viewed in pieces in a back yard in London it resembled a pile of scrap stainless steel with some very unusual plywood additions which badly needed stripping and painting. These units are designed to fit on conventional transoms and our boat has a canoe stern so additional framing would be required to support the standard unit around the rudder. I nearly did not buy it. With no past experience of vane steering I thought it was all too complicated and expensive. Luckily I changed my mind, went back and Hasler Vane No. 66 became mine.

I have since spent many happy hours watching our vane in operation and all credit must go to the man who designed it. When a twelve ton sailing boat is sailing along in strong winds with no human intervention, no power consumption and all forces working in harmony, to me there is no better feeling. Ours is a heavy boat to steer and being naturally lazy we now leave all that to Carly (you’re so vain). Crossing the Bay of Biscay last summer we had 30 hours of force six to eight on the beam with a large cross swell. Throughout we never touched the steering and found we had covered 120 miles in the right direction without leaving the safety of the companion way. Carly is the best helmsman we have on the boat, she doesn’t need feeding, nor does she get tired and go off course.


She does however need setting up correctly.
Firstly if not fitted correctly to the original instructions she will not work. Critical measurements are given in the instruction manual and these must be followed religiously.

Secondly the sails must be balanced and set correctly. Remember all that stuff about centre of effort over centre of lateral resistance. Well it’s all vital when using a vane. A long keel helps with directional stability as well.

Set the boat on the course you want. Set the sails correctly to that course. Drop in the vane and the self steering will keep the boat at the same relative angle to the wind. The windier it gets the more accurate the self steering becomes.

The big test is whether or not it works on a run, the hardest point of sailing for vane steering. Ours works on a run quite happily when there is enough wind to counter the waves but quite often we furl the main and use balanced headsails or spinnakers to make things easier for the vane.

Fine adjustment of the course made good can be completed with the fine adjustment line which alters the angle at which the vane is set to the wind. It can also be completed by adjusting the sails. Sheeting in the head sail will bear the boat a few degrees away from the wind. Sheeting in the main sail will turn the boat up in to the wind. Fine adjustment can be completed by any of these methods or a combination of all three. If the sails are not set correctly self steering will not work and a full understanding of sail set is necessary.
The cry from the cockpit that the vane steering is not working properly and the boat is way off course often follows someone messing about with the sail set.

Conditions the self steering vane does not like are:

When the wind is shifting around and gusting. The vane will follow the wind direction and you must allow the boat to alter course to suit the changing wind to keep the sails set correctly. Obviously in narrow channels and with other boats about, this is not practical.

When the wind is dropping and the waves are too big for the wind. The waves will knock the boat off course and the vane will not be able to react quickly enough to bring her back.
When there is no wind and you are motoring.

Hasler Self Steering

Wind Vane Steering for yachts was first developed as a practical device for model yacht races in the early thirties. It was not until 1955 that effective vane gears appeared on full size yachts – Ian Major’s Buttercup and Michael Henderson’s Mick the Miller.

When Blondie Hasler originated the Observer Single-handed Transatlantic Races it gave a great boost to vane gear development.

Blondie started developing Vane Gears in 1953 and remained leader in this field for a long time afterwards, gaining practical experience including four Atlantic crossings, single-handed in his radical junk rigged Folkboat Jester. Each of these crossings is believed to have set a new record for boats of less than 35 feet overall, culminating in a passage of 33 ½ days from Newport, R.I. to the Solent in July 1964. Out of a total of 12000 miles Jester was steered by hand for less than fifty miles.

The now well known Trim Tab system was the first to be perfected incorporating a differential linkage to eliminate the over-steering tendency of earlier gears. In the first Single-handed Transatlantic Race in 1960, Jester was fitted with a prototype Trim Tab Gear and advanced experiments were carried out, mainly with wind vanes of different sizes.The next milestone in the history of Vane Gears was Hasler’s invention of the Pendulum Servo system in 1961 . For the first time it enabled yachts with counter sterns to be steered effectively in all conditions without needing complicated modifications to the rudder and rudder stock.

Subsequently, the winner of the 1968 Single-handed Transatlantic Race, the 57 foot ketch, Sir Thomas Lipton using a BP1 Hasler Gear, was steered manually for only twelve hours during her record breaking passage between Plymouth, England and Newport. R.I. The next six yachts home were also steered by Hasler Gears with the exception of the Proa, Cheers (3rd) which had no vane gear at all.
Hasler Vane Gears have also been successfully used on a number of very long voyages including the great circumnavigation’s via Cape Horn, made by Bill Nance (Cardinal Vertue), Sir Francis Chichester and Sir Alec Rose.

The first commercially produced Hasler Pendulum Servo Gear was sold in May 1962 and the first Trim Tab Gear in March 1963.By December 1970 over 600 gears had been supplied to yachts all over the world. Sizes range from the yacht (12′) Nonoalca, sailed by Captain Verity from the USA to Ireland, to the 59′ ketch British Steel . Also among the largest is the yacht Islander which has already been sailed single-handed by the owner, Cmdr. Tom Blackwell from England to Australia via Panama.

Most of the wind vane self-steering sytems used today are based on the servo pendulum vane gear designed by Blondie Hasler in 1961.

How a Pendulum Servo Gear works

In this particular system a Servo Blade ‘s’ is hung vertically over the stern with its shaft passing through a Servo Frame ‘f ‘ (see drawing on right). It can be turned like a rudder by the Servo Tiller ‘a’.
The Servo Frame also has fore and aft bearings ‘x’ and ‘y’ which allow the whole assembly to swing from side to side like an athwartships pendulum.

Steering ropes ‘w’ are connected to the top of the Servo Frame and lead from it through sheaves ‘c’ to the tiller.

Initially the vane is free to weathercock on its shaft for manual steering. If the vane turns when the latch is engaged, the servo blade also turns. The flow of water past the immersed blade forces it to swing sideways ‘d’ pulling the ropes, tiller and consequently the rudder, bringing the yacht back on course.

How a Trim Tab Gear works

When a Trim Tab Gear is at rest with the Vane ‘V’ unlatched the Tab ‘t’ simply trails in the water flowing aft from the rudder ‘r’ (see drawing on right) without impeding manual steering.

As soon as the Latch ‘L’ is engaged and the tiller left free the vane gear will steer. If for instance the yacht veers off course to port, the vane will be turned in a clock-wise direction by the wind.This movement is connected through to the tab which turns to port. The resulting servo power swings the yacht’s main rudder in the opposite direction bringing the yacht back on course.

A differential linkage between the vane and tab on the Hasler gear overcame the oversteering troubles experienced with some other Trim Tab gears then available on the market.

Linking in an Autohelm

When the wind drops and the motor goes on the vane becomes useless and a few years ago we added an autohelm to the vane mechanism for use when motoring or sailing in light airs.

The biggest problem was how to support the Autohelm unit in such a place that it can be reached to connect and disconnect and for fine adjustment. A remote control would be a good addition to our system but we found this too expensive.

A weekend standing up in a dinghy saw a support arm made out of timber fitted to the self steering frame. The drive arm of the autohelm drops on to a pin fitted at point X on the diagram so it controls the direction od the paddle. The autohelm can then easily be lifted off the pin and left supported in a rope sling when the vane is in use

To everyones surprise the system is very effective and we have the smallest, cheapest autohelm unit driving a 12 ton boat with minimal power consumption.

The autohelm replaces the vane but all the power still comes from the servo pendulum. With the autohelm attached the vane is disconnected and swings free.

This system has now been tested over 4000 miles in all conditions. Using the Autohelm when sailing in light winds works well. This system has the added bonus that as the wind increases the Autohelm “auto ejects” by bouncing off the pin and that is the time to start using the vane.
We were lazy before…….we never have to drive now.

The final phase of this installation is to have a support arm built in stainless steel as it is in a vulnerable collision location and can take high loads.

When I fitted the Autohelm there was very little information available on the web and Auto Helm themselves maintained that they could not support this type of installation.

Our Autohelm unit will spend its entire life on a reciprocal course to the one it thinks it is on, i.e.going backwards, but you soon get used to pressing the wrong course adjustment button.

Surveying a vane steering system.

It is basically common sense. The frame and securing bolts can be hammer tested in the usual way and obviously need to be rigid. Inspect welding for cracks.

The control lines from the pendulum to the tiller take a huge force and need replacing regularly. Check all eye splices, blocks and block security. It is normal for the control lines to be attached at the after end of the tiller (in fact there is a critical measurement for this) and this positioning gives you an idea of the forces involved. Try steering a heavy boat holding the aft end of the tiller.

Check teeth on cogs and free movement of mechanism.

Check the system for engaging and releasing the vane. Accidental engagement can cause a lot of damage, particularly if the boat is left on a mooring.

Check for play in the servo pendulum paddle as the securing bracket is susceptible to opening up.
Check vane and paddle for wood rot.

It is not possible during the course of a land based survey to determine if the vane steering system works effectively. This can only be determined from sea trials.

Mike Chadwick
BMSE Surveyor

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