Frequently Asked Questions

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The two products use completely different principles.

The Hydrovane is an auxiliary rudder windvane which works completely independently of the boat’s own rudder. The main rudder is locked in position and the extra rudder is asked to do ALL the steering. The power to turn the Hydrovane rudder ONLY comes from the AIRVANE, which has very limited power.

The MONITOR is a servo pendulum windvane. The airvane input is only used to turn a small semi-balanced water paddle, which is a “POWER GENERATOR” that turns THE BOAT’S wheel or tiller. The harder it’s blowing and the faster the boat is going, the more steering power is generated. The WATER FLOW develops the POWER to turn the BOAT’S RUDDER.


A brief history of windvane self-steering principles

50 years ago the earliest windvanes had an airvane that was directly connected to the boat’s tiller or wheel. It was discovered that not enough power was produced to turn the boat’s rudder. The next basic step in selfsteering history was an airvane that was coupled to a smaller, auxiliary rudder like the Hydrovane, which was introduced around 1970. This principle was later improved by other manufacturers who added a trimtab to the auxiliary rudder (like the Auto-Helm, which is made by Scanmar). It is easier for the airvane to turn the small trimtab which then moves the auxiliary rudder, which then steers the boat.

The real breakthrough came when Blondie Hasler developed the servo pendulum system. The airvane turned only a small paddle which developed lots of power from the water pressure on it; this was used to control the boat’s own rudder. It is generally accepted that the winning principle for windvane selfsteering is the servo pendulum. With the exception of Hydrovane, which only makes one type of windvane, all the major manufacturers make servo pendulum windvanes, with a few making auxiliary rudder models as well.


Most experienced cruisers have personal experience with only one brand of windvane. To get a wider picture of windvane use we suggest that you look at past single-handed around the world races, the BOC and Around Alone. As a cruiser you probably do not plan to sail in the Southern Ocean but when you confront your first gale in your well planned fair-weather ocean voyage it will be comforting to know that your windvane has not only survived Southern Ocean conditions, it has also excelled in them on many different boats and in conditions ranging from light wind to heavy gales. During the period 1982 to 1999 these races were run every four years. Here are some windvane facts:
No Hydrovane was EVER chosen or used in these races, even though the Hydrovane was a familiar British product and had been around since 1970, the early days of windvane self-steering. (BOC stands for British Oxygen Corp. and the races were organized out of England.)
Only one (1) auxiliary rudder windvane was used all these years. It was in the 1986 race and the manufacturer discontinued this model and now only makes a servo pendulum gear.
With the exception of the single auxiliary rudder type mentioned above only servo-pendulum windvanes were used. In total, twenty (20) Monitors were successfully used and in the 1995 and 1999 races ONLY Monitor windvanes (12 units) were used. This was a result of stellar performance in two previous races. It should be pointed out that these windvanes were paid for. They were NOT free promotional products.

Heavy Weather

The Hydrovane rudder is very small if you compare it with the boat’s rudder - one size of auxiliary rudder cannot be expected to work well on all boats. It might serve in light to moderate winds on medium sized boats but not in bad sea and wind conditions on larger boats. Hydrovane has enlarged their rudder in order to sell to larger boats, and reports of shaft breakage or bending are becoming more common due to increased rudder area and higher loads.

The Hydrovane’s power comes only from the airvane which has a very weak signal strength, especially downwind with light apparent wind.

The Monitor’s power comes from the water pressure on the servo-paddle when it is rotated by the airvane. This power turns the boat’s rudder, which is designed to steer the boat in ANY conditions.


The Monitor has positive yaw dampening. In downwind conditions the Monitor will immediately recognize if there is a tendency for the boat to broach. This could happen in big seas, especially if the boat is over canvassed. If the boat starts slewing sideways (the start of a broach) the water paddle will be pushed in the opposite direction by the pressure of the water on it. This designed feature will instantly correct the course and the broach will be avoided. In this situation, the signal comes from the water, not the airvane!

Positive yaw dampening is one of the most important but least understood design features of the servo pendulum design. The Hydrovane does NOT have positive yaw dampening. If the boat starts slewing sideways at the beginning of a broach the pressure on the Hydrovane rudder will not counter the yaw, it will exaggerate it.

The Hydrovane works, to a limit – but it obviously cannot be expected to steer as well as the boat’s own rudder in rough seas. Hydrovane states on its website that in heavy weather an electronic autopilot, steering a compass course, can be used in conjunction with the Hydrovane for “greater security” or some-such!!!! Isn’t that a tacit admission that their unit has trouble steering in heavy weather? In addition, an autopilot attempting to steer a compass course will more often than not be fighting the windvane attempting to steer by apparent wind, putting additional strain on both units. Even if the autopilot is set to steer by the wind the autopilot and the Hydrovane will most certainly fight each other since the input will still be different most of the time. We would NEVER recommend using an autopilot at the same time as a windvane.


The Hydrovane is a nice and clean looking windvane with a proper appearance. Aluminum castings are used with stainless steel tubing. The Monitor is all stainless and has a four point attachment system which takes more room on the transom. However the load, which is already lower with a Monitor, is better spread this way. We also personally like the looks of shiny stainless and our favorite quote is: THE MORE IT BLOWS, THE BETTER IT LOOKS! In other words, our priority is PERFORMANCE.


One of the selling points that Hydrovane makes is that it is a “ready to go” emergency rudder. Scanmar has solved the problem in a different way. Together with race management for the BOC/Around Alone the M-RUD was developed for single handed around the world racers, who were required to carry an emergency rudder. The M-RUD is a conversion system that will turn the MONITOR into a rigid emergency rudder. The pendulum is locked with a stainless steel bracket and a rudder replaces the Monitor’s servo-paddle. Spectra support lines will make the installation easier and give additional support for side loads.

We feel that this is a much better solution instead of sailing around with the permanent emergency rudder always in the water. That is a little bit like sailing around for years with the life raft inflated just in case the boat would start sinking. When the M-RUD is taken from its storage bag under deck you know that it is just like new. The M-RUD was first proved itself in 1995 when a 50 foot BOC race boat lost its rudder and the M-RUD steered the boat for 2,300 nm to a safe harbor.

A permanent emergency rudder can be damaged if the boat’s main rudder breaks off. If this happens you go from two rudders to none. Damage could also be done to the boat’s main rudder if a log gets stuck between the two rudders. This happened to the owner of Scanmar during his own early circumnavigation with an auxiliary rudder type of windvane (not a Monitor). The boat’s rudder was damaged and the windvane shaft was bent.

On a boat with a MONITOR the log would most likely just push the servo oar to the side and the log would get free. If this did not occur, the MONITOR safety tube, which is designed to fail in an overload, would buckle and most likely this would prevent damage to both the boat’s rudder and the MONITOR.

If your main reason for buying a windvane is for the emergency function we suggest that you look into the SOS EMERGENCY RUDDER – A BETTER SOLUTION FOR A LOT LESS MONEY.


The Monitor is protected by:

Its own ability to swing to the side
. It is not a rigid spade rudder. It’s just like a boxer bending backwards to avoid a punch. It is a more forgiving principle.

The MONITOR has a sacrificial safety tube between the hinge and the water paddle. This mechanical fuse is an inexpensive replaceable part that is designed to buckle in an overload or collision. A replacement safety tube is included with a Monitor purchase but it is seldom needed. Most boats that circumnavigate do not have to use it.

The Hydrovane, and all other auxiliary rudder type windvanes manufactured today, HAVE NO OVERLOAD PROTECTION. The Hydrovane is a rigid spade rudder with no inexpensive and easily replaced designed failure point.


With the Hydrovane and all other auxiliary rudder systems it is very difficult or impossible to take the rudder in and out of the water at sea. The procedure is difficult even in a calm harbor. Most of the time the Hydrovane rudder is left permanently in the water. Mounting the rudder at sea is very difficult or almost impossible.

The Monitor paddle is very easy to take in and out of the water. From the safety of the cockpit you simply pull the red release line and then pull the paddle up to resting position with the safety line/pull-up line. You can even do it in full speed, easily!

To put the Monitor paddle back in the water you simply release the safety line and it will automatically swing down and lock in position. If you are going faster than about 4 knots you might have to luff the boat to slow her down and repeat the procedure.

Why is it important to be able to take the rudder/servo oar in or out of the water?

Maneuverability. We all know that it is difficult to maneuver a sailboat in a crowded harbor. With the addition of a second rudder, it will make the boat very hard to control, especially in reverse.

No vibration under power. The rudder/water paddle is located behind the propeller wash on all windvanes and is therefore subject to vibration under power. The solution is either to go much slower than you would like to or take the paddle out of the water. With the Monitor this is easy; not so with the Hydrovane and most other windvanes.

No wear when not steering. When hand-steering, under autopilot, at anchor or at the dock you will get no wear on the Monitor since nothing is in the water. In addition, you will not get any growth on the paddle so it never has to be painted.


The MONITOR is made of 316L stainless steel, the best material for a saltwater environment when mixing of materials will cause corrosion. Hydrovane is using stainless tubing mixed with aluminum castings that would have to be replaced if there is collision damage – and if you’re half-way around the world, shipping can be a problem. Stainless steel can be cut and welded almost anywhere in the world, but welders competent in aluminum welding are comparatively uncommon.


Swim ladders in the middle of the transom can cause a dilemma for the sailor who wants to put a windvane on his boat. Hydrovane has solved this by telling their customers that you simply put the windvane off-center. Scanmar will not do this because we strongly feel that this is faulty advice. We will tell our customers to move the swim ladder off center and put the windvane in the correct place, in the middle of the transom. There must be a reason why you have never seen a sailboat design with one off-center rudder. If you have seen a design with a rudder off-center it is a race boat and we can guarantee that there is another rudder off center on the other side, a total of two rudders.

The reason for this is obviously that when the boat heels, a single off-center rudder could go out of the water or at least have a heavily reduced rudder area in the water on one tack. On the other tack the rudder is too deep and increased drag and higher loads are the result. In big waves and strong winds you need the full rudder in the water. We feel that Scanmar is more honest, or maybe we are just more knowledgeable. Our priority is that the windvane should work properly. Swim ladders can be mounted in many places on a boat. On a boat with a swim platform we can understand that this can be the preferred boarding location but the better solution is to move the swim ladder off-center or install a Monitor with the optional Swing-Gate mount.




It's true that the the Hydrovane has no operating lines connected to the boats wheel or tiller, since the Hydrovane's rudder is supposed to steer the boat in all conditions. The MONITOR is designed to use the mechanical advantage that the boat’s wheel has. The windvane is connected to the boat’s wheel by means of an adapter with a built-in on-off clutch, allowing instant changing between hand and windvane steering. Hiding the lines by running them directly to the rudder quadrant might seem attractive, but you could not then easily undo them when you wish to hand-steer, and it is an advantage to be able to easily inspect the lines at all times. The lines are normally run forward both on the same side of the boat leaving the other side of the wheel always free, and the lines can be easily unrove when the windvane is not being used.

In reality lines do not seem to be a problem once you start using a MONITOR. The only time you have to be at the wheel is when the windvane and sail trim are set up. When that is done the windvane takes over and the person on watch can retire from the steering position. He or she can spend time on the fore-deck, under the dodger, cooking, navigating, reading or resting in a bunk. Supervision is reduced to looking for ships and a glance at the compass now and then. When you are in port you want to be able move around freely on the boat and then the pendulum lines can be coiled just like the sheets and other lines that are only used at sea. The Monitor’s water paddle can be raised and lowered remotely from the cockpit, so the paddle is safely up when not in use. The Hydrovane's rudder is permanently fixed.


The ARC is a good start to help mostly inexperienced cruisers in their first ocean crossing. It is a fairly easy voyage most of the time. The weather is normally quite good and most boats have a crew of several people. Many boats also have several autopilots and some of the ‘ocean virgins’ like to steer, so the windvane might not be as severely tested as in regular short-handed cruising. Quite a few sailors in the ARC have had Hydrovanes and we feel that this has a lot to do with the exposure that Hydrovane has purchased by being the only official windvane recognized by the ARC organizers. When Scanmar inquired about advertising in the ARC communications, which are given to all the participants, we were told that only one manufacturer in each equipment category was accepted and Hydrovane had purchased that right from the ARC.


Scanmar never sells our products based on which has the higher price. Priority #1 is that we sell the right and the best product for the boat. We have three different brands of windvanes, they work on different principles, and are suitable for different boats and steering systems. We have the benefit of being able to recommend the RIGHT gear for YOUR boat. The prices of our windvanes are more or less the same so price should not be the deciding factor. If you want to compare the Hydrovane with our auxiliary rudder windvane, the Auto-Helm, you will find that our windvane is about a third cheaper. If you have investigated windvanes and come to the conclusion that the MONITOR is the best windvane on the market you will be pleasantly surprised to find out that the MONITOR price also is about a third lower than the price of the Hydrovane.