Self Steering - Hydrovane Selfsteer

WHY IS THAT? WHY ARE THOSE CONVERTS THAT SWITCH FROM A SERVO PENDULUM SYSTEM HAPPIER WITH A HYDROVANE?

Certainly for all those reasons listed above - but we want to emphasise that all servo pendulum systems, when matched against a Hydrovane, are comparatively unsophisticated . Once engaged they do a meandering sort of course correction without any means of tuning or straightening its course. In a flat sea you are stuck with a ‘snake wake’ – extra miles traveled – but far worse is the exacerbation of the yaw in a heavy sea – meaning a more uncomfortable (how can one gauge comfort in a bad sea?), longer and less safe passage.

With a Hydrovane you can straighten that wake to within a few degrees of a perfect course in a calm sea but far more importantly is the significant reduction of yaw in a heavy sea because:

NATURAL STABILITY - Only with the main rudder fixed can the boat be stable in a bad sea. You can imagine the stability produced by having the main rudder fixed in its balancing direction.
SENSITIVTY ADJUSTMENT - The vane axis can be set in a position that greatly tempers the response of the vane. The vane is the sensor that triggers all activity. The Hydrovane vane axis can be adjusted from a vertical position to up to thirty degrees off vertical. That adjustment does not sound like much but what it does is dramatic. It changes the physics of the transmission of the sensory instruction from the vane to the delivery system that turns the rudder. In comparison all servo pendulum systems lack this adjustability for sensitivity and are set at a fixed axis setting - no ability to adjust for sensitivity. Hopefully we shall see you at a boat show someday where we can demonstrate to you this major affect.
RUDDER SETTINGS – The Hydrovane has three different settings for the degree of rudder angle - can change amount of steerage applied.

The natural stability of the fixed main rudder combined with the unique ability to tune the system for sensitivity and steerage sets Hydrovane apart.

HYDROVANE IS SOPHISTICATED - with ease, it gives a more comfortable ride:

More direct course - faster
Calmer - less yaw
... safer!

I TOO HAVE HEARD THAT SERVO PENDULUM SYSTEMS ARE MORE POWERFUL THAN THE HYDROVANE. IS THAT TRUE?

This is a complicated question because the quick answer is deceiving. The answer is yes, a servo pendulum does generate a lot of power - but only when the boat is moving quickly through the water. The converse is the case when the boat is moving slowly - it is deficient in power - a condition that is worsened if there is any excess friction in the system - stiff rudder, arduous connecting lines etc.

We have too often heard owners of servo pendulums that are very proud of their units but advise that when off the wind they only work in a minimum of 15 or 20 knots of wind!! See our comments elsewhere on the ideal application of a servo pendulum system - high friction systems have significant weaknesses.

In comparison with a Hydrovane this power issue only becomes relevant for larger boats as the Hydrovane system is more than adequate for lighter boats. We suggest maximums of 40,000 lbs. or 18,000 kgs. for the Hydrovane - and always happy to tell you about many 50,000 lb. or 23,000 kg. boats that also have glowing reports about the performance of their Hydrovanes – having adapted to its limitations – see section on Oversize Boats. The Hydrovane’s power is limited to the size of its rudder and the speed of that rudder through the water. As explained above it is a more efficient system than the servo pendulum systems but it can only do so much. The question is whether a servo pendulum would outperform a Hydrovane on your boat - and in what conditions?

If you have ever had the chance to see a servo pendulum operating in bad weather you would better appreciate where that comment about its power comes from. Its activity can be described as perhaps violent as it wrenches the wheel/tiller from one course to the next. One certainly wants to stay clear of that section of the cockpit. We do suggest that there is some overkill in that performance – excess yaw which is self inflicted – again see explanations above. On those same boats if they had a Hydrovane the demonstration would not appear so spectacular – but if you did stick you head over the stern you would marvel. The comparison is like the difference between the less skilled hard working rookie and a skilled athlete that makes a play look so easy as the Hydrovane rudder nimbly flops back and forth with immediate response to dramatic course changes but confidently not over-reacting to the ‘fakes’ that would have fooled a human helmsman.

If your boat is over 35,000 lbs or 16,000 kg. you should consider the pros and cons of the two systems. If your steering system is at all stiff or the rudder is not balanced you will find that a servo pendulum will certainly impress you in heavy weather - at least it better impress as it could disappoint in lighter airs. A big boat with a system that is only good off the wind in 20 knots + means so little usage ….. and too much of the autopilot. If the Hydrovane has a shortage of power in challenging conditions the remedy is more conservative sailing - a bit less sail - but better course travelled, more comfortable....and probably no slower - just not such an aggressive ride.

Our customers with larger boats who have had experience with both systems have a hard time in comparing the heavy weather performance – as it is all so difficult in those conditions and they would have adapted the steering system to the conditions – meaning that if the Hydrovane was being overwhelmed they would make appropriate adjustments as they would with a servo pendulum.

For big boats the ideal application for a servo pendulum system is like the boats used by long distance solo racers: a balanced spade rudder on a balanced boat that is steered by a tiller that is located near the transom - the tiller should be so light to the touch, even in bad conditions. In that configuration a servo pendulum is at its best.

Power is only an issue for larger boats
Most boats are not ideal applications for a servo pendulum
Powerful display of a servo pendulum is deceiving - some of which is overdone - to rectify self inflicted over-steering
Hard to compare power in heavy weather - the elements produce such opposition – technique is to de-power the vessel so that steering system can manage
Hydrovane system is more efficient in its use of power
Hydrovane is tolerant of many inadequacies that would hurt the performance of a servo pendulum
Be wary of acquiring a system for its power and suffering inadequate performance in normal and lighter conditions

Email received Dec. 21, 2005:

Please evaluate your Hydrovane with the Pacific Plus from WindPilot. This unit also has a servo, which I believe makes it work better in heavy weather with my boat which is 11,64 long. This unit is also over 1000 Euro cheaper.

I am pleased you are trying to evaluate and compare the Hydrovane with Windpilot’s Pacific Plus. We are going to the Düsseldorf boat show for the first time next month. We expect to often hear your same questions in Germany. I do believe the next best system to a Hydrovane is Peter Forthmann’s Pacific Plus. Peter says of it:

“A double rudder system is a perfectly balanced unit, a closed system with no variable components. A double rudder will still have plenty in reserve long after conditions would have overwhelmed a servo-pendulum system.”

You have expressed two concerns: 1) Power 2) Price. I will address those issues and also point out some other differences.

POWER – RUDDER IS SOURCE OF POWER – NOT THE SERVO BLADE – A double rudder system gets all its steering power from its auxiliary rudder – 1) its size and 2) the degree it turns. In comparing the Hydrovane and Windpilot rudders I believe they are both about the same size- about .25 sq. m. (although we will have a new rudder soon that is extended by an extra 15 cm. or 20% more power). The Hydrovane rudder has three settings for the amount of rudder needed: 15 degrees, 30 degrees and 45 degrees. Windpilot is fixed at 30 degrees. On the measure of size of rudder they have equal power. By their ability to provide steerage the Hydrovane can be turned to a greater degree – hence it has more power – probably not significantly more – but more!

BOTH SYSTEMS HAVE MORE POWER THAN THEY NEED TO POWER THEIR RUDDERS IN MODERATE TO HEAVY WEATHER - Many are confused by the source of power for those rudders. The servo system can produce much more power but that is either unnecessary or meaningless to this discussion because both the Windpilot and Hydrovane rudders have all the power they need – meaning both have adequate power to turn on command – any extra power is a waste – with one exception explained later. Hydrovane’s rudder is powered directly by its very large vane. Windpilot’s vane is much smaller and only used as a sensor that instructs its servo oar. The movement of the oar powers its auxiliary rudder. So its power increases with boat speed and Hydrovane’s power increases with wind speed. The result is that both systems have more than enough power to turn their rudders – so, the notion of a more ‘powerful’ servo system is bogus as the extra power is simply not used. As both the Hydrovane and Windpilot have more than enough ‘power’ to move their rudders – and if both rudders are moving on command and both are of the same size then they are equal in ‘power’. As mentioned the Hydrovane probably has an advantage in that it can apply a greater rudder angle if needed and Hydrovane’s new rudder will have more power yet – although I am not sure if you actually need our larger rudder for your Feeling 39. In conclusion, Hydrovane and Windpilot systems should be equal in power with a slight advantage to Hydrovane in conditions that require greater amounts of rudder.

There is one exception to the need for the extra power of the servo system and that is the larger high performance racing ‘sleds’ which can achieve 10 knots+ in only that much wind when reaching. In those conditions the Hydrovane’s vane would have little apparent wind – hence insufficient power. Hydrovane has alternative methods of dealing with those conditions – but we need not deal with that now. Of course, your boat would never have this problem.

RUDDERS - The Hydrovane rudder is cast nylon in a true NACA hydrofoil shape. It is made of solid nylon which is truly unbreakable. Incidentally that is why we dare to build a larger rudder. I believe the Windpilot rudder is plastic on foam – not a true NACA foil shape. In comparison the Hydrovane rudder is stronger and a more hydrodynamic shape. Those differences are subtle though as I am not saying the Windpilot rudder is weak nor is its shape detrimental – just not quite as good.

HYDROVANE IS TOPS IN LIGHT AIR PERFORMANCE – SO LITTLE FRICTION - Power is also a major issue in light airs – as much sailing is done in light airs. The Hydrovane system has so little friction it can perform in 3 to 6 knots of wind. The Windpilot needs a certain amount of boat speed to perform. We believe no system can match Hydrovane’s light air performance.

PRICE – Our prices are about equal I believe – if you compare a Hydrovane to the Pacific Plus II – as it should be. I do notice a typo in Windpilot’s comparison chart – the same in Peter’s book – I believe he is referring to a lighter version that we no longer produce. Hydrovane should be rated for boats up to 50 ft. (15.25 m.) not the 33 ft. (10 m.) as shown by Windpilot. (Actually there are many owners of bigger boats up to 25 ton (22,700 kg.) boats that are pleased with the performance of their Hydrovanes.)

CAN OFFSET AND LESS OBTRUSIVE – A significant advantage for you is how the Hydrovane will compliment your platform not obstruct it. The Hydrovane shaft and brackets will also double as ideal handholds.

SUMMARY AND OTHER ADVANTAGES OF A HYDROVANE OVER A PACIFIC PLUS

Same steering power in moderate to heavy winds – with slight advantage to Hydrovane for its larger rudder angle….and a bigger rudder is coming soon
Hydrovane superior in lighter winds
Equivalent pricing
Ability to offset to enhance swim platform – not obstruct it.
More easily accommodate a dinghy on davits.
Simpler structure – less items to break
Less obtrusive – less vulnerable to collisions in a marina
More sophisticated course control – Hydrovane’s unique 1) sensitivity adjustment and 2) rudder steerage adjustment are not available on Windpilot – produces straighter course, less yaw, more comfortable, safer

CAN A HYDROVANE FUNCTION IN TANDEM WITH AN AUTOPILOT ON THE MAIN RUDDER - BOTH ON/ENGAGED AT THE SAME TIME?

Most certainly. That is a feature of only auxiliary rudder systems - and is such a convenience! In situations of fast changing weather conditions or even the simple process of engaging and disengaging the HYDROVANE an easy management technique is to click on the autopilot. Once sails have been adjusted and control achieved then the autopilot can be turned off. Finally you take the wheel or tiller and find that ‘sweet spot’ or position to locked it off. It is that simple.

In major storms many have used this technique when the Hydrovane appears to be challenged to the maximum and needs all the help it can get. That is often the case in the early hours of a storm when the seas are square and chaotic. Once the storm has blown for a while and the seas become more regular then the autopilot can be turned off. Incidentally, the HYDROVANE is proven to be quite capable of steering the boat in very high winds.

This technique is also ideal for the aggressive sailors – for surfing conditions – to compensate for rapid changes in apparent wind direction. Many set the autopilot to respond only for course deviations greater than 10 degrees or more - so the autopilot is dormant most of the time and only activates when needed.

Unlike other systems a HYDROVANE and an autopilot easily function in tandem/together
When used in tandem each helps the other – in total, enormous steerage power – or less work for each
Ideal for dramatic weather changes requiring major sail adjustment
Many use this technique even for engaging and disengaging the HYDROVANE
Comforting to use in storms when uncertain – can turn off once control is regained
Ideal for aggressive sailors in surfing conditions or to be safe when carrying too much sail - set for course deviation of greater than ten degrees

Note - This technique is not to be confused with retrofitting a tiller style autopilot onto the HYDROVANE. That is an entirely different feature. To clarify - this tandem function involves the engaging of the main autopilot that operates the main rudder while, at the same time the HYDROVANE is also engaged and operating - two rudders are better than one.

IF MY BOAT IS LARGER THAN THE RECOMMENDED LIMITS AND I DID INSTALL A HYDROVANE WHAT KIND OF PERFORMANCE CAN I EXPECT?

The Hydrovane only delivers its certain amount of steering. For heavier or faster boats its abilities diminish with weight and speed. In 2006 we introduced a bigger rudder and in 2007 we improved the balance of that rudder. The Hydrovane system is now more capable of handling bigger and faster boats. We too would like to know where the saw-offs are.

We do know of many boats in the 25 ton (23,000 kg.) range that are pleased enough with their Hydrovanes – and theirs are all with the old smaller rudder. They are ideal candidates to upgrade to the new rudder for improved performance.

Generally, we can say that bigger boats would probably find a HYDROVANE could steer their vessels at least ‘most of the time’ if not ‘all of the time’– subject to the ‘balance’ of the boat. If the vessel is losing control then the solution is to re-visit the trim of the sails or maybe ease off the sheets or probably reduce sail. That is the compromise – speed. Of course, the more ‘balanced’ the boat is the more sail it can keep up.

Another technique that is only possible with an auxiliary rudder system is to use your autopilot simultaneously/ in tandem with the HYDROVANE. Yes, with the HYDROVANE engaged you may also turn on the autopilot on the main steering system – then you will have two rudders steering the boat instead of one – tremendous steering power. This is helpful for big boats in a storm when there is concern whether the Hydrovane can handle the job. Once sails have been adjusted and control regained or the storm settles down, the autopilot can be turned off. This technique is also useful for normal operations like engaging and disengaging the Hydrovane or when making sail changes.

Finally, the other major reason to have a HYDROVANE is the back-up/emergency rudder and steering system. No matter how large the boat a HYDROVANE rudder and its overbuilt structure would be quite capable of getting any cruising yacht safely back to port. The importance of a boat having steerage is second only to its ability to float.

Should function, at the minimum, most of the time
Sail more conservatively, probably more comfortably, perhaps a bit less speed
When challenged, can employ the autopilot to run in tandem/simultaneously with windvane
Have a truly reliable, 'ready to go' back-up emergency rudder and steering system

Comparison - HYDROVANE and Servo Pendulum Systems

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CONSIDERATIONS -Autopilots and Mechanical Self Steering