COMPARE HYDROVANE TO OTHER SELF STEERING SYSTEMS
SPS – Servo Pendulum Systems – A device on the transom with a line to the boat’s wheel or tiller – common brand names: Aries, Cape Horn, Fleming, Monitor, Neptune, South Atlantic, Sailomat, Windpilot SAR – Servo driven Auxiliary Rudder – Often called a ‘double rudder’ system – a servo blade powering an auxiliary rudder – means 2 separate blades in the water on the back of the boat – common brand names: Fleming, South Atlantic, Windpilot HV – Hydrovane auxiliary rudder self steering system – A vane that directly powers and guides its own rudder
Are not autopilots the easiest solution for steering? After all, they are the ‘devil we know’.
With the advent of autopilots it was felt that the demise of the older mechanical self steering systems was only a matter of time. But it is now apparent that is not to be – they both have their place. Especially for ocean passages, you cannot beat the quiet simplicity and reliability of a good self steering system – the boat being powered by the wind and steered by the wind. The autopilot is still a very desirable tool to have on board. It is the only solution for motoring and very adequate for short coastal trips. A mechanical self steering device is the ideal solution for long passages. It is worth pointing out that only the best quality autopilots that the racers use can compare with a good mechanical steering system. The deficiencies in most autopilots is outlined in section 6 below.
Why not invest in one of those high quality autopilots?
Three reasons: 1) The cost is big (double or up to quadruple conventional systems), 2) reliability issues persist and 3) the power needs are a bit of a tyranny. NKE in France led the way with a system that the high speed racers could use. Brooks & Gatehouse now has such and perhaps Ray Marine is competitive. Those are hydraulic systems with multiple boat and wind sensors that are fed to a computer that analyzes the data. To keep the systems going they need lots of power and a back-up system as break downs are considered to be inevitable. When the back-up is needed the ‘sailor’ then must find a fix for the de-commissioned unit as it inevitably will be needed to be put back in service.
Why is Hydrovane different from other self steering systems?
- Does not use a servo oar – not an ‘SPS’ nor an ‘SAR’
- Only system powered by the wind. Vane directly turns its own rudder. That rudder steers the boat. The main rudder is locked in place – does not move.
- One of the few that does not need to be located amidships. Can be installed anywhere on the transom…….. anywhere!
- Will deliver its certain amount of steering power to any boat.
Any boat? Well, it will deliver its power to any boat but there is a size limitation and some issues with certain multihulls. The only exceptions are:
- Big boats: heavier than 20 to 25 tons/18,000 to 23,000 kg.
- Some multihulls: performance boats that can rapidly accelerate or decelerate and some have configuration issues.
Isn’t that the same for the other systems?
No, most other systems are of the servo pendulum style. They must be installed amidships or pretty close to it.
Is that such a big issue – being installed amidships?
Well, it is for the modern boats with platform style transoms because the assemblies would partially obstruct what is otherwise a feature of the boat.
Are there any other limitations to installing a Servo Pendulum System (SPS)?
Yes, the boat’s main rudder must be easy enough to turn. A servo system actually only pulls a line by about 10 inches/25 cm. – about enough to move the ships wheel a half a turn in each direction. Although they do not move the wheel by much (typical wheels have 3 revolutions – stop to stop) it is enough to do the job …. or put another way, many helmsman do a lot of over-steering. The point is that with only those 10 inches to work with any detracting factor, such as stiff steering or long lines prone to stretch, then, the system cannot perform satisfactorily.
Are you saying that a servo pendulum system does not work on some boats?
Yes. Any of the servo pendulum manufacturers can advise on the suitability of their system for your boat or for that matter you could go to any of the web forums to ask that question.
What characteristics of a boat are best suited for Servo Pendulum Systems (SPS)?
The ideal configuration would be a tiller steered boat with a spade rudder very near the transom. For such a boat wheel steering instead of a tiller is probably just as good. Put another way, a center cockpit boat, with the wheel far from the SPS and a rudder entirely fixed to the trailing edge of the keel would probably be too much for an SPS to handle….. at any speed.
Isn’t that why some manufacturers offer a Servo driven Auxiliary Rudder System (SAR)? The SAR works on all boats whereas an SPS is somewhat limited in the range of boats it is suited for.
Yes, exactly. There are four of the SPS manufacturers who offer both SPS and an auxiliary rudder system that is powered by a servo blade:
- Windpilot – Germany
- Fleming – Australia
- South Atlantic – Argentina
- Royal Perfect – Germany
- Sailomat – US – terminated production some years ago
They can work on any boat (up to a certain size) because they are auxiliary rudder systems?
Yes, an auxiliary rudder is indifferent to whatever boat it is on. An auxiliary rudder delivers its certain amount of steering power unaffected by whatever it is attached to – unless it suffers the flow of ‘dirty water’ (water that for some reason is moving in an adverse direction).
Then, like a Hydrovane, they are suited for almost any boat?
Well, any boat as long as the unit can be positioned amidships. Because of the servo blade which itself must be amidships or very near to it.
Why must the servo systems be amidships?
If the servo blade ever jumps out of the water it will have nothing holding it in place – letting go of its control of the wheel/tiller. That ‘letting go’ for a few seconds would be of less consequence if the boat was on course and the blade was trailing but if the blade was in the midst of a course correction it would suddenly lose control of the wheel which, if in heavy conditions, could cause a crash gybe or such.
Is the auxiliary rudder type of servo system better than the standard servo pendulum systems?
Those manufacturers say they are. We cannot help to concur that an auxiliary rudder system is very desirable. Not only having a back-up rudder in place but nothing makes a boat more stable than having a fixed main rudder……. And the bonus that the boat’s main steering system gets long holidays when otherwise it would have been working its tail off.
But if an SPS does all that these other auxiliary rudder systems do why have the extra expense?
Exactly, there are so many very happy owners of the basic servo pendulum systems who have no real incentive to change. It’s a good testament to self steering of the excellent performance they get from their systems. Well, we do have to ask them or for those contemplating what to purchase we ask:
- The expression is ‘the harder it blows the better it goes’. Too much of our sailing is in lighter winds. The big question is: ‘What boat speed is needed to get reliable performance?’
- Space on a boat is at a premium – especially cockpit space. What value would you attach to regaining that territory?
- Tensioning of those lines to the wheel is so critical. Some are comfortable with that chore, others find it annoying at times and to some ………….. a never ending challenge.
A big virtue of the SPSs is their price – cheaper than the SARs but better yet is the bargain of finding a good used one. Used SPS’s are plentiful, much more so than the SARs – always a good supply available at good prices.
That expression: ‘The harder it blows the better it goes’ is used for both servo versions – the SPS and SAR. Does that mean ‘the less it blows the less it goes’?
Actually, that expression is used for all self steering systems including the HV. For any of the servo systems they need boat speed to perform. For the SPS that minimum boat speed is critical. On an appropriate boat a speed of perhaps 2 knots might be the threshold for performance and the number only gets higher depending on the power needed to move the boat’s rudder. For the SARs the 2 knots or so is the same for all. An HV is not affected by boat speed – only needs 4 to 6 knots of apparent wind on its vane in order to perform.
Can a Hydrovane that is offset really perform as well if it was amidships?
Lacking evidence to the contrary but having that nagging doubt we finally had a chance to experiment to find out for sure. With our engineer and an engineering student from the Southampton University (UK) engineering department we finally found a volunteer with a Beneteau with a platform transom. We fabricated a devise that allowed us to re-position the Hydrovane on the transom and proceeded to test performance. Our engineer in particular felt there must be better performance at the amidships position. Well, his intuition, like all of us, was wrong. The Hydrovane rudder when turned only needs water pushing against it to do its job. The turning force does not change at whatever location. Why would it?
OK, my intuition was wrong on that one but why wouldn’t a big offset be disastrous when the boat is heeling and the Hydrovane is on the weather side and possibly its rudder jumps out of the water from time to time?
Yes, intuitively problematic but in reality it is not a big issue because:
- The boat, with its main rudder fixed, has considerable directional stability. Even if the rudder jumps out of the water for a few seconds not much would happen in regards to course.
- A boat heels most when heading upwind – but that is the easiest point of sail for steering. Most boats almost steer themselves when going to windward.
- Using a self steering system one discovers that excess heeling – carrying extra canvas – is counterproductive – boat is not well balanced – needs less sail for the same or even better boat speed.
- Steering is far more critical when going downwind – but the boat does not heel so much when off the wind
The big ARC rally reports a low percentage of the boats with self steering – and worse, those with self steering are often not that enthusiastic. Why?
There is something peculiar about the ARC. Most boats in that Rally could have used an HV and a good portion could suit other versions of self steering. For all the HV users there is no reason why each one of those boats should not have given the Hydrovane a rave review. For instance, have a look at the email from the Motiva 49 that lost its rudder in the last ARC – go to http://www.hydrovane.com/emails-testimonials/ and scroll down to the February emails – here is the heading:
EMAIL RECEIVED FEBRUARY 2013 & DECEMBER 2012 – Motiva 49 – steel, 24 tonnes (52,800 lbs.) – lost main rudder in 2012 ARC “… the vane was working just great for the first five days ….. in what I will describe as rough weather; nothing extreme; 4-8 m waves and winds 25-40 knots and from behind” “…everybody on board was amazed by its easy operation and the fact that it seemed to steer better than our autopilot.” “It was a great help after the rudder loss surely. Combined with our drogues (we lost our second one) and trimmed sails we managed to hit Cape Verdes, after all!” “…without it we might have ended up on the shores of Senegal.” “Anyway, I think it is a good story thanks to the Hydrovane.”
Of interest, the Motiva 49 had his Hydrovane delivered to Las Palmas and installed days before the start ….. and the Motiva is well over our recommended weight limits. We know that many ARC participants are typically less experienced at offshore sailing , boats well crewed, lots of new gear ….. steep learning curves. We advertise that ‘It just works’ as many discover but others suffer from:
- Improper installations
- Untested – Never used their HVs before
- Never having sailed without an autopilot – skills at sail trimming need improving
If those boats are having problems why do we not hear from them? We would walk them through the POOR PERFORMANCE section on our website at http://www.hydrovane.com/instructions/tips/#6 to solve the problem. We are always happy to work with those customers until they have their unit working properly.
That lack of self steering systems on such a major ocean crossing rally does say something. In all their preparation why wouldn’t more boats cotton on to the advantages of self steering?
The sequel to that rally and others tells the story. The best example is the Pacific Puddle Jump rally where each entrant has probably already done a feeder rally like the ARC or Baja HaHa and is committed to cross the largest ocean of them all – the South Pacific …… and onwards. The route for that rally is a multi-start from both Mexico and Panama – 3,000 miles to the Marquesas, all meeting in Tahiti (nearly 4,000 miles done to that point and still a fraction of the way across). Anyways, these more experienced sailors predominantly have self steering systems. It is common to see all boats in a South Pacific anchorage with self steering.
Why are all these systems so expensive?
Volume! The market is too small. A manufacturer is lucky to sell 100 units in a year. If they could sell 1,000 or more the prices would be so much better.
All the auxiliary rudder systems are more expensive yet. Why is that?
The difference in loads on the different types of systems is enormous. An SPS is only pulling a line by 10 inches/25 cm. – doesn’t take that much. An auxiliary rudder is by itself turning the boat – certainly a ton or more of pressure on it at times. In order to cope with those loads without breaking the materials used must be of higher quality. That is most likely the reason that Sailomat stopped making their SAR – getting too expensive to keep it all together.
In the evolution of this technology it seems that the auxiliary rudder systems (SAR & HV) are the most evolved but the SPS are still holding their own?
Yes, that is true. If money is not a constraint, then you do get more with an auxiliary rudder type system. We would argue that for the bit extra of cost the sailor gets a lot more with an auxiliary rudder ……. and you know which one we tout. A little history – the evolution of self steering systems:
- BASIC SERVO PENDULUM SYSTEMS – After various efforts with trim tab systems Blondie Hasler invented the servo pendulum system in 1961. It was Nick Franklin who achieved the first successful commercialization of self steering with his Aries gear that was introduced in 1968. Selling 1,000 per year in his best years (before autopilots) and a total of 11,400 by the time he quit in 1992. Today Aries units are built in Denmark. Similar systems have been produced for years by perhaps a dozen other companies. The main brands still produced today are Aries, Cape Horn, Monitor, Sailomat, South Pacific and Wind Pilot.
- SERVO DRIVEN AUXILIARY RUDDER SYSTEMS – In 1976 Sailomat came out with the Sailomat 3040 the first of the servo blades driving an auxiliary rudder. Production was terminated in 1981. Failures due to the far greater loads on the system were probably the cause. In 1986 Peter Förthmann of Windpilot introduced their version which is still in production. Since then some other servo pendulum manufacturers have developed their upgrades: Fleming in Australia and more recently South Atlantic in Argentina ……. and maybe more to come.
- HYDROVANE’S AUXILAIRY RUDDER SYSTEM – Derek Daniels started developing the Hydrovane in 1968. Most features of the current model were seen by 1980 although refined in the 1986 model. Derek’s notion from the beginning was for an auxiliary rudder powered by a vane. It was a simple concept that has taken much development to achieve. The Curry’s bought the business in 2002 and have made a number of improvements with more on the drawing boards.
2. Compare Hydrovane to a Servo Pendulum System (Aries, Cape Horn, Monitor, Sailomat, Wind Pilot Pacific etc.)
All self steering systems sold today are tried and proven. The Hydrovane is one of the most expensive – 25% to 40% more than good servo pendulums. Here are some of the reasons why:
- EASIER TO OPERATE – A unique completely ‘user friendly’ system
- NO LINES IN THE COCKPIT – just ‘click’ into gear – no constant adjusting and re-tensioning of the control line
- OFF CENTER – Can be installed ‘off center’ – to accommodate boarding ladders, swim platforms etc.
- EMERGENCY STEERING in place and ‘ready to go’
- CLEAN PROFILE – permits use of davits, boarding ladders, swim platforms etc.
- RELIABILITY – nearly unbreakable
- UNMATCHED COURSE CONTROL – only system able to adjust power and sensitivity – can ‘straighten your wake’
- NATURAL STABILITY with fixed main rudder – less yaw, more comfortable, faster and safer
- HEAVY WEATHER MODE – immediate and tempered course correction minimizes yaw – better boat motion, shorter passages
- LIGHT AIRS – so little friction in the system – can perform in as little as 4 to 6 knots of apparent wind
- EASY INSTALLATION – Flexibility in positioning of brackets – no critical location requirements. Suitable for situations that are difficult or impossible for other systems: off centre, hydraulic steering, external rudders, centre cockpits and stiff steering, multihulls
- TANDEM WITH AUTOPILOTS – can be used in tandem with autopilot on main steering – helpful in storms, convenient for sail changes or even when engaging and disengaging the HYDROVANE.
- NEGLIGIBLE MAINTENANCE
REPORTS FROM THOSE THAT SWITCH FROM A SERVO PENDULUM SYSTEM TO A HYDROVANE
Those that have switched to a Hydrovane – were happy enough with their servo pendulum systems but wanted to get the lines out of their cockpits with the bonus of knowing they have an effective back up steering system. Once they have experienced the Hydrovane they report to us:
- PLEASURE in no longer having those lines in the cockpit.
- SURPRISE at how easy it is to engage and disengage – remembering the hassle of tensioning and fiddling with those lines.
- “MAGICAL” they say about its performance downwind in light airs.
- NO REGRETS – nothing lost in performance
- CONFIDENCE AND COMFORT in knowing that a back-up steering system is in place
3. Compare Hydrovane to an Auxiliary Rudder Servo System (Fleming, South Atlantic, Windpilot Pacific Plus etc.)
- OFF CENTRE – All servo systems should be installed on the centerline or very close to it. – see http://www.hydrovane.com/our-product/off-center/ for an explanation. At least 60% of Hydrovanes are off center. Even extreme offsets of 40 inches/1000 mm or more have no effect on performance.
- RELIABILITY – RISK OF STRUCTURAL FAILURE – The servo driven rudders have two items in the water with the aft servo blade a distance behind the auxiliary rudder. The challenge is to make that much more structure strong enough. Even if plenty strong the two items in the water adds to their vulnerability. The HV is very compact, close to the transom with a record of only the rarest of failures: several years since a bent shaft at sea (only one or two since the switch to a Super Duplex steel in 2009 and no factures) and many more years for a broken rudder. In fact our new heavier design of rudder (2009) has yet to have a breakage.
- RISK OF DAMAGE IN MARINAS – Bigger structures are simply more vulnerable.
- YAW DAMPENING – All servo systems have little or no method of adjusting their performance. They will always over steer or understeer to whatever extent is inherent – hence a certain extra yaw. The auxiliary rudders are big improvement to the yaw as ‘nothing stabilizes the boat motion more than having a fixed main rudder’. Only the Hydrovane can adjust its performance to the extent that in a flatish sea it can steer a straight course which translates to a straighter course in bigger seas. This is done because the HV has two methods of adjusting its performance: 1) 3 Ratio settings (3 gears so to speak) that provide changes to the amount of rudder applied and 2) its Variable Axis (all other systems have fixed axes) can adjust the responsiveness of the vane from a ‘nervous nellie’ in the vertical to a very tempered response when fully inclined to deal with ‘washing machine’ conditions in heavy weather…….. and any position in between.
- POWER –The steering power for all auxiliary rudder systems is dependent strictly on the size of its rudder. Coincidentally, all the systems we are comparing to seem to have about the same size rudders. That means that they all have about the same steering capacity as long as they can turn their rudders. Such power issues are a big issue for the conventional servo systems as each boat needs a certain boat speed in order to have enough power to do its job. That is one of the main reasons why the servo manufacturers developed servo driven auxiliary rudder systems – to solve the lack of power for those certain boats (center cockpits, stiff steering etc.). All systems have all the power they can use when the wind is strong. The differentiation is in lighter airs. The HV needs about 4 to 6 knots of apparent wind to perform. The servo/auxiliaries need perhaps 2 to 3 knots of boat speed. Hydrovane is now developing an extendable vane for the speedsters – light big boats that can do 7 or 8 knots reaching in less than 10 knots of wind leaving little apparent wind for the HV vane. Experiments have proven the effectiveness of bigger vanes.
- REMOVABLE RUDDERS – Only Hydrovane’s rudder is designed to be removed when not in use – and so easily dropped off by ‘popping’ out its locking pin – it just drops off…… and equally easy to reinstall – stick the rudder onto the shaft stubb (5 in./125 mm) and insert the pin. All other systems have cumbersome arrangements that mean the rudders are more likely to be left on when not in use which means: growth on the rudder, extra wear of bearings, affects steering when motoring and rattling noises when at rest in sloppy anchorages/marinas.
- RUDDER – The HV rudder is a solid single piece of nylon poured in a mold to make a shape that is a true NACA profile that slips cleanly through the water with minimal drag. None of the other rudders can match the HV version, for strength or shape. As mentioned already we have yet to see the current version break – even after severe impact with whales.
- SEMI BALANCED RUDDER – The Hydrovane rudder is not only a true foil (like the wing of a plane) but its shaft hole is in a position that minimizes the power needed to turn the rudder.
- PLATFORM/STEPS MUCH MORE USABLE – All servo systems are anything but an enhancement to the transom – generally an obstacle that occupies more than its fair share of space. For boats with a scoop or platform transom the Hydrovane will make the platform/steps safer and more usable:
- OFFSET – Can be offset to one side to preserve the platform/steps, passageway and swim ladder
- HANDHOLDS – The 2 inch (50mm.) tubes of the shaft and the struts of the brackets can be configured to enhance the platform – not obstruct it……. will double as ideal handholds – finally easy to board and de-board your dinghy.
- PRICING – All these auxiliary rudder systems are about the same price – a good bit more than the standard servo systems – a difference that is well worthwhile for its improved performance and their ability as emergency steering.
- EMERGENCY STEERING – The HV comes with its Tiller installed. Push the Ratio out of gear and its Tiller directly turns the rudder – just like a dinghy. It is emergency steering that is ‘in place’ and ‘ready to ‘. The servo auxiliary systems require a little more doing to achieve the emergency rudder. The standard servo systems that offer an emergency retrofit end up costing as much as a Hydrovane with a very cumbersome structure to install in the event of an emergency.
- COMPACT PROFILE – We would like to say that the Hydrovane has an elegant appearance.
4. 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 non auxiliary rudder 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.
- 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. BACK TO INDEX
5. Compare non-electronic steering systems to autopilots
DISADVANTAGES OF HAVING ONLY AN AUTOPILOT
We all are happy enough with our autopilots: set the sails, turn on the autopilot ……. the boat seems to be doing OK – what am I missing?
- SAILING ABILITY IS NOT SO GOOD – Unless your autopilot has a wind sensor it is not a very good sailor. In fact, it is a crummy sailor because the wind is never coming from a fixed direction. The wind’s direction is always meandering. Conversely, with a wind sensor style self steering system your course will always hug the wind – always holding that same angle to the wind – means the sails are always in trim – optimized for the conditions – boat will sail faster with a pleasanter, consistent boat motion. The self steering system becomes the instructor. If the steering is struggling the solution is found in the sail trim. The sailor becomes more sensitized to sailing performance, innately improving trim.
- OVERWORKED – With an auto pilot, if it is struggling to hold course, the crew is never the wiser – hence the burn out of autopilots. The bottom line is that sailing with an autopilot is a crude form of sailing – good enough – but no incentive to improve sail trim or performance.
- VICTIM OF ELECTRICAL FAILURES – The autopilot could be just fine but a myriad of other failures could mean the batteries do not have enough power to keep the autopilot going.
ADVANTAGES OF USING NON-ELECTRONIC SELF STEERING
- RELIABILITY – No worry of break-downs that can render the autopilot useless
- ELECTRICITY – Major reduction in use of electricity
- INDEPENDENCE FROM ELECTRICITY – In the event of electrical failure the steering will be just fine
- REDUNDANCY – More than comforting is the confidence given in knowing that your boat, with self steering, has enormous redundancy built in against the unforeseen. A perfectly fine autopilot can be crippled by thousands of unrelated failures: bad fuel, clogged filters, slipping alternator belt, dead batteries, engine/generator issues …………. on and on ………
- HEAVY WEATHER – Solves much of heavy weather steering challenges
- BOAT MOTION – Steers a better course to the wind.
- COURSE – Magnetic course is not good enough – The wind direction is never constant. When sailing, the course should always be the same angle to the wind – requires a wind sensor not a magnetic course.
- CALM – Peaceful and quiet operation of self steering – no motors or engines
- CONFIDENCE – Security of steerage – creates confidence in the boat’s equipment
A STORY – Told to us by George Day of Bluewater Sailing Magazine. A story of smaller boats with Self Steering beating a bigger boat with only an autopilot.
Self Steering Systems Steer a Better Course – Always Trim to the Wind Three boats left Fiji together all heading to New Zealand – 35, 45 and 55 footers. The smaller two had self steering but not the big boat which depended on its autopilot. .. The course was mostly to weather. The smaller boats beat the larger boat by a considerable margin because of their self steering. . The reason is that the self steering systems allowed those boats to hug the wind, always keeping their sails trim – optimizing both their sail trim and course. With an autopilot the big boat had to keep falling off its course in order to keep its sails full – to avoid being headed. .. At the dock or at an airfield watch the Windex at the masthead or windsock at the end of a runway. They are constantly changing direction. The wind direction is constantly in flux. .. If the course of those three boats could be plotted minute by minute the result would show the course of the boats with self steering looking akin to a plotting of the stock market – very jagged with considerable diversion in direction. Whereas, the autopilot generates a virtual straight line course – which one might assume is shorter and faster – but not so. The big boat was hardly ever in trim – almost always untrimmed, sailing inefficiently – neither optimising its sails nor its course – meaning slower boat speed and actually off course. Conversely, the boats with self steering, although sailing ‘all over the place’ they fully exploited their sail trim keeping their boats precisely at the same direction to the wind – optimizing boat speed and achieving the best possible course – and also much better boat motion. .. . Another example of the superior speed of self steering over autopilots see Tony Gouch’s website story “Windvane vs. Autopilot” – http://www.taonui.com/ . . NOTE – Many autopilots do have a wind sensor option which would solve the above issue – subject to any positioning and electronic issues. For whatever reasons, not many wind sensors are sold for autopilots. BACK TO INDEX
6. COMPARISON HYDROVANE VERSUS SERVO PENDULUM SYSTEMS
|SUITABLE FOR||All Sailboats including: centre cockpits,hydraulic or a any other steering system, offsets are no problem, slower multihulls Hydrovane is indifferent about what boat it is on||All sailboats except: hydraulic steering, steering that requires many turns of the wheel, stiff steering, long distance from transom to wheel, other high friction systems, no offsets – Performance can vary considerably on different boats|
|MAXIMUM DISPLACEMENT||About 50,000 lbs./23,000 kgs.||Varies – some over 40,000 lbs./18,000 kgs.|
|MAXIMUM LENGTH||55 feet/17 m. or so||Varies – some to 60’/18 m.|
|COMPLEXITY OF INSTALLATION||2 Brackets – Flexibility in position||Multiple arms and blocks Location critical|
|COMPLEXITY OF EQUIPMENT||Simple shaft and drive unit with vane and rudder attachments||More complex structure on transom linked to wheel/tiller by system of lines and blocks|
|INITIAL SET-UP||Should perform on 1st sail||Could be tuning process|
|COURSE DIRECTION||Easy – precise worm gear control||Varies – many have a simple line control|
|COURSE CONTROL – SENSITIVITY & POWER||1. Adjustable Vane Axis Yes – Adjust sensitivity of vane – vertical (0 degrees) for light air to 30 degrees for storm 2. Adjustable Ratio Control Yes – 3 power/steerage settings for rudder – 1:1 for 40 degree rudder, 2:1 for 25 degree rudder, 3:1 for 15 degree rudder||No – Fixed at 20 degrees No – Fixed – typically at 2:1|
|CHAFE OF CONNECTING LINES||No lines to wheel/tiller||Require regular tensioning and replacement|
|OTHER WEAR AND TEAR||Self steering unit Minimal||Self steering unit Generally durable|
|Main rudder system Major reduction in usage||Main rudder system Under constant use|
|STEERING||To weather/upwind Excellent||To weather/upwind Excellent|
|Reaching in bad seas Good||Reaching in bad seas Good|
|Running Good to Excellent||Running Good to Excellent|
|Heavy wind Excellent||Heavy wind Excellent|
|Light wind Excellent||Light wind Varies – Excellent to poor|
|Very light wind Good||Very light wind Good to poor|
|EMERGENCY /RUDDER||Yes – ‘Ready to Go’||Some have a retrofit system – generally, no emergency rudder|
|ADAPTABLE TO AUTOPILOT||Yes – to tiller supplied||Yes – but can be finicky|
|DURABILITY||Well built – over engineered||Varies – generally well built|
|OPERATE SIMULTANEOUSLY WITH MAIN AUTOPILOT||Yes||No|
|OFF CENTRE INSTALLATION||Yes||Generally No – always discouraged|