Monitor Windvane

Monitor — The Self Steering Solution

There are many different systems of windvane self-steering. Trim tab, auxiliary rudder and servo pendulum systems are just a few. The development of the servo-pendulum principle represented a break-through in windvane self-steering. As the boat moves faster with stronger winds, the power of the servo oar increases and this gives ample power to turn the boat’s own large rudder.

The Monitor steering system is powerful and has positive yaw dampening which makes it possible to steer straight in difficult downwind conditions. The more it blows, the better the Monitor likes it. Consensus of opinion is that the servo-pendulum principle is the best method of self steering for most boats.

A self-steering gear in a class of its own.

  • Works without electricity
  • Can be repaired on-board
  • Makes no noise
  • Extremely dependable
  • Loves heavy weather
  • High resale value
  • BOC tested

Servopendulum Principle

The most efficient way to steer a boat is to use the boat’s own rudder which was designed to steer the boat in the first place.

The servopendulum works as follows:

Imagine yourself holding an oar with its blade behind a boat that travels forward. You will do fine as long as the edge of the blade is aligned with the direction of the boat. If you twist the oar, even a fraction, the water will hit the flat surface of the blade and you will be unable to keep the oar straight – it will swing to the side. A tremendous leverage is created from the blade, through the shaft, to the end of the oar where you are holding on.

A servo pendulum gear uses this great leverage to keep the yacht on course. An oar or paddle is suspended like a pendulum from the stern of the boat. As long as the yacht is on course, the oar blade trails on the center line. The airvane is the sensor that controls the servo pendulum oar. When the boat wanders off course the airvane will sense this and rotate the oar. The flow of water hitting the blade broadface causes the pendulum oar to swing to the side with great force. The pendulum is connected through lines to the wheel or tiller and the resulting movement of the yacht’s rudder brings the boat back on course.

BOC–Around Alone (AA)

Monitor has been the favorite windvane in the BOC/AA the singlehanded around the world race. Why is that so important for a cruiser?

We are very proud of our record in the BOC/AA. In the 50-foot class there were Monitors on three boats in the 1986–87 race. In the 1990-91 race we had five Monitors in the race and in the 1994–95 there were seven Monitors with no other windvane in the race!! WHY?

Because in the two previous races the Monitor performed and other vanes had not, or they were never selected. In the 1998-99 race there were fewer boats. Five of them had windvanes and once again, they were all Monitors. Almost all other commercially-available windvanes have never had a single unit in these races! We consider ourselves very fortunate to have been involved in the BOC/AA. In our first BOC/AA, we were nervous because our equipment would be tested in conditions far beyond anything previously experienced. Monitors had sailed around Cape Horn many times, but these BOC/AA boats were bigger, they were racing and they stayed in the Southern Ocean for many months! It was an international event followed by the media and gear failure could not be covered up.

Fortunately, we never had a BOC/AA disaster. More importantly, we learned that there was room for improvement. It has been a fantastic opportunity for research and development. Instead of waiting for 5–6 years for the feed back from a circumnavigation with a normal cruising boat, we could check the equipment in 9 months—equipment that had seen 28,000 miles of conditions more severe than most cruising sailors would experience in a lifetime. BOC/AA became our “R&D Department.” We would like to point out that all the BOC/AA Monitors were purchased. They were not “sponsored” by Scanmar—BOC/AA sailors would not take any equipment unless they thought it was the best. The Southern Ocean is extremely unforgiving and dangerous.

The Only Windvane in the BOC

The BOC is considered the ultimate equipment test and it is obvious that this benefits cruisers and racers alike.

The Monitor must be considered the best windvane on the market because we are the only manufacturer able to back up this statement with such an impressive endorsement.

More than 31 changes and modifications have resulted, and today’s Monitor is a big improvement over the earlier model, even though these units perform well and are still sailing. The BOC has tested our equipment beyond imagination and this will benefit the regular cruising sailor who is bound to be caught in bad weather eventually. When this happens it should be comforting to know that you are not the test pilot. The BOC has helped Monitor to evolve into a truly finished product.

Since 1986 the Monitor has been the windvane of choice for the racers in the most grueling gear test known to sailors—the BOC. In this singlehanded around-the-world race men and equipment are tested beyond imagination. Few sailors will ever encounter the conditions that these sailors experience for months in the roaring forties and screaming fifties. In three consecutive BOC races the Monitor windvane has been used in the most difficult sailing conditions known to man and boat. This has given us at Scanmar International invaluable feedback, helping us to build the strongest and best performing windvane on the market.<

In the 1986–1987 BOC Mike Plant, Hal Roth and Mark Schrader used the Monitor and proved that a properly designed windvane could handle a 40 – 50ft boat in ultimate conditions.

In the 1990–91 BOC the Monitor was the favorite windvane. Among the eight Class II (40–50 ft.) boats that finished the race, seven had windvanes. Five of these vanes were Monitors.

Robin Davie – Cornwall

With the 1994-95 BOC Challenge now over, it is worth reflecting on the great service, mileage and performance that your Monitor has given me during its 2nd Circumnavigation, which brings its total mileage up to 85,000 miles.

“In the severest 60- to 70-knot southern ocean storms the Monitor has done the steering, keeping Cornwall tracking downwind at its full 8 kts hull speed regardless of the sea and swell which at times looked to me like traveling mountains of water and surf.

The highlight, or lowlight, depending on how you look at it, was undoubtedly my dismasting and jury rig sail some 2500 miles from halfway between New Zealand to the Falkland Islands and around Cape Horn. All I had to do was rig a very strong jury rig, point Cornwall in the right direction and the Monitor did the rest. There were three storms over 60 knots, and with the Monitor steering I never had to steer, and never felt endangered.

At the opposite end of the scale in near calm conditions, with engine problems and flat batteries for the final 4 days into Uruguay and again for the final 10 days approaching Charleston, the Monitor steered in conditions of very light winds and light airs, so that I was able to continue my normal daily routine, and did not need to resort to steering myself.

Of course everything wasn’t perfect, and I did manage to break several plywood vanes, or rather the breaking seas over the stern in the Southern Ocean did, and similarly when a nasty cross sea picked up Cornwall and chucked her sideways the safety tube on the paddle buckled, but then that is what it is supposed to do. I very quickly and easily had the spare tube fitted and Cornwall back on course.

Knowing the lack of reliability experienced with electronic autopilots by my fellow competitors during two BOC Challenges, I am left in no doubt that both of my BOC circumnavigations would have been very much more difficult had it not been for the Monitor being the main and principle self-steering gear on the Cornwall.

Similarly, I firmly believe that serious cruising folk who are going to cross oceans should fit a Monitor, learn to use it and be familiar with it, so that when the inevitable autopilot breakdown occurs they too will be able to keep sailing without being shackled to the wheel 24 hours a day. They, like me will come to love their Monitors, and will find themselves using the autopilots less and less.”

BOC–AA Conclusions

In spite of the successful and continuous use of Monitor windvanes in the cutting-edge BOC races, one still may hear “that the windvane is a gear of the past, the future belongs to autopilots.” Why? Experienced cruisers certainly do not agree. They have learned that they must be able to fix everything on board themselves and that one thing you can depend upon is an autopilot to fail sooner or later! In isolated areas there are no specialists to repair complicated electronics. Out at sea you are helpless unless there is an electronic genius on board.

For example, the BOC makes three stops in major cities and factory representatives go over all the autopilots. If necessary, bad units are replaced. In order to make sure that breakdowns at sea can be handled a large number of complete back-up pilots are carried on board together with a variety of electricity producing equipment and batteries. The additional costs in time and money are obvious. In contrast, no boat has ever needed more than one windvane and a few spare parts for maintenance.

Boats With Wheel Steering

The Monitor is designed to work with any well designed mechanical steering system with less than four turns lock to lock. Cable and quadrant, rack and pinion and worm gears are the most common. With more than four turns, a complicated block system in the lines from the Monitor to the wheel is required. This would give more movement at the wheel. In general, we do not recommend such a system because of increased friction and complexity.

The pendulum lines are connected to the Monitor wheel adapter, which is made in stainless steel and designed to fit wheels with 3, 4, 5, 6, or 8 spokes of any diameter. It will fit on either side of the wheel. If it is mounted on the inside, it is out of the way and hardly noticeable.

If the boat has a cockpit mounted autopilot, the Monitor wheel adapter normally goes on the outside. The drum is 1-3/4″ (44mm) deep and has a diameter of 7 inches (18 cm). The pendulum lines, which are included, are wrapped around the wheel adapter. The adapter has a non slip clutch with a split second release which is engaged when the Monitor steers and disengages when you want to steer manually.

A servo-pendulum gear like the Monitor cannot be connected to the wheel if the boat has hydraulic steering. The reason: there is slippage in the hydraulic and often too many turns lock to lock. With a bypass system on the hydraulic pump, the lines can be led directly to a permanent emergency tiller on deck and the tiller can face either backwards or forwards. Such a system is excellent provided that it does not interfere with the interior layout of the boat. (Scanmar’s SAYE’S RIG is often the best windvane for large, midship cockpit boats with hydraulic steering.)

Boats With Tiller Steering

With a tiller steered boat the tiller can face forwards or backwards to gain more space in the cockpit. A small stainless steel plate is attached to the tiller 20–30 inches from the rudder shaft.

It normally is attached on the bottom side of the tiller. It can be done with large wood screws or through bolted. Wrap around stainless steel ties are also enclosed for the person who does not want to drill holes in the tiller. The plate has a jaw which is designed to accept the links on the stainless steel chain. The chain is tied to the starboard pendulum line on one side and to the port line on the other. The reason for the chain is that it is very easy to adjust for trim by moving to the next link without undoing any lines. When the Monitor is disengaged you simply pull the chain out of the jaw and let it hang under the tiller.

Can lines in the cockpit be avoided?

Yes they can, but in our opinion, lines in the cockpit are necessary with the servo pendulum gear and the disadvantage is very slight. Keep in mind that with the Monitor doing all the steering you do not spend much time at the helm where the lines are! You only do it when you set or change the course. You spend most of the time at more convenient places – at the navigation station, in your bunk, in the galley or under the dodger.

It normally is attached on the bottom side of the tiller. It can be done with large wood screws or through bolted. Wrap around stainless steel ties are also enclosed for the person who does not want to drill holes in the tiller. The plate has a jaw which is designed to accept the links on the stainless steel chain. The chain is tied to the starboard pendulum line on one side and to the port line on the other. The reason for the chain is that it is very easy to adjust for trim by moving to the next link without undoing any lines. When the Monitor is disengaged you simply pull the chain out of the jaw and let it hang under the tiller.

If you are interested in purchasing a windvane, or just want to know more information, please contact us discuss your needs.