Windvane Report E-Book

Peter Foerthmann

• Herausgeber: tredition
• Kategorie: Ratgeber
• Sprache: Englisch
• Veröffentlichungsjahr: 2021

Seitenzahl: 220

Beschreibung

Peter Foerthmann has been the first port of call for bluewater sailors seeking advice in steering matters for decades. His unrivalled expertise - the product of a lifetime developing and manufacturing windvane self-steering systems and contemplating their every complexity - continues to draw enquiries from all over the world. Now available in six languages, his specialist books present the state of the art and provide reassurance - should any be needed - that the fundamental rules of physics still apply in a world increasingly dominated by bits and bytes. This book recounts both the author's personal history of almost half a century in the windvane self-steering segment of the international marine industry and the story of how a business that once built everything by hand has managed to transform itself into what must surely be one of the smallest high-tech engineering companies in existence. The Windvane Report shares the milestones of the author's progress over the decades and recounts some of the remarkable disputes that have erupted in the sector as well as discussing and comparing important technical developments in the field. A roller-coaster ride through the highs and lows of a life on and by the water, this book offers the reader a wide-ranging insight into how Windpilot and the man behind it came to be what they are today.

Leseprobe

PETER FOERTHMANN

WINDVANE REPORT

A journey through time

Copyright: © 2021 Peter Foerthmann

Umschlag & Satz: Sabine Abels – www.e-book-erstellung.de

Photos: Peter Foerthmann

Verlag und Druck:

tredition GmbH

Halenreie 40-44

22359 Hamburg

978-3-347-33080-1 (Paperback)

978-3-347-33081-8 (Hardcover)

978-3-347-33082-5 (eBook)

All rights reserved. No part of this publication may be reproduced, translated, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the publisher and author.

Contents

Foreword

50 years of mechanical self-steering at sea

Prevailing system types today

Auxiliary rudder systems

Servo-pendulum systems

Double rudder systems

Types of boat

Long-keelers

Fin and skeg

Deep fin keel and spade rudder

Centreboard or internal ballast

Catamarans

Force transmission to the main rudder

Windpilot and Autopilot together

Combined Solution on Monohulls

The ultimate limits of windvane self-steering

The emergency rudder factor

A quick history lesson

Effective self-steering

In extremis – losing the rudder

Comfortina 32 “Be Atitas” – rudder attacked and broken by orcas in the Atlantic

Bandholm 27 Seawind – broken rudder in the North Atlantic

Catalina 42 “Blue Sky” – emergency rudder required in the North Atlantic

Arion 29 “Element” – lost rudder on the Baltic

Choosing a system – misguided advice

How I see it

Hand-built or industrially manufactured?

A static market

Windpilot – a brief history

Copycats

Don’t look back in anger

Sailomat

Windmaster, Germany

Niro Petersen, Germany

Voyager

Fleming

Neptune Windvane

South Atlantic

Beaufort

Intrigue and court cases

Windpilot USA

The land of sharp elbows

Doris and Dirk

Sales channels

A singlehander’s lonely fight

Windhunter power generator autopilot hybrid

The high court case

The Icons

Hydrovane, Canada

Aries, UK

Monitor, USA

Aries, Denmark

Golden Globe Race 2018

Wave systems

Knock downs, Rollovers and Pitchpoles

Designated points of failure

Overload protection: Achilles’ heel

Aries

Conclusion

A score of comments on the Windvane Report

Istvan Kopar – Puffin – USA

The final Subterfuge – A low blow after the bell

The Puffin riddle

The hare and the tortoise?

My Waterloo moment

This message will self-destruct in X minutes

Creative licence

Interview: taking stock of the GGR

Riding the razor’s edge – Why the man from Windpilot says No

Assessing the damage

Completed the course

La longue route

The Story of a disgrace

The Key

The press and the Golden Globe Race

Web error

The stony path of truth

Channels and target groups

Research

In Conclusion

FOREWORDSail in balance, live in balance

Self-Steering Under Sail is both the title of a book full of information about how to make yourself obsolete in your own cockpit and the subject that has dominated my working existence, bringing me pleasure and friendship and showing how a person can live life in balance on the back of a few simple rules.

The very thought of sailing makes me sleepy: my boat comfortably balanced with its Windpilot in control, the skipper dreaming contented dreams in his bunk – over and over again with never the slightest hitch (but sometimes with a Paolo Conte soundtrack). How wonderfully sublime to lie back and feel a well-balanced boat (with windvane self-steering system) sailing itself. All too soon though such thoughts are overtaken by weariness, the mind surreptitiously lulled into sleep because of that mysterious irresistible link between the sounds of the sea and the weight of the seafarer’s eyelids – a trap one can only escape with an ingenious and effective invention, an uncomplaining slave for the helm that leaves the skipper to sleep in peace while keeping the boat in sync with the wind and waves and ticking off the miles at pace.

The windvane sector is pretty small even at the global level, so it is very easy to attract attention: expressing an opinion (repeatedly and vehemently) is really all it takes. The endless loop of my life. A journey through time that already spans close to half a century – with more to come.

50 YEARS OF MECHANICAL SELF-STEERING AT SEA

A windvane self-steering system steers a course dictated by the apparent wind angle, so provided the crew trim the sails properly, it will keep the boat moving for as long as the wind blows. The wind direction is always the critical factor, of course: with a favourable wind it is possible just to sail the direct compass course to the next waypoint, but the direct compass course will not be any help at all with the wind on the nose!

The book Self-Steering Under Sail describes twelve different types of windvane self-steering system, three of which dominate the market today:

The effective length of the lever that supplies the power to the system essentially determines the amount of force that can be applied to the helm and hence the size of boat the system will be capable of managing.

Hilfsrudersystem Hydrovane on Ovni 435

PREVAILING SYSTEM TYPES TODAY

Auxiliary rudder systems

An auxiliary rudder is an additional rudder capable of steering the boat independently with no connection to the main rudder. An auxiliary rudder needs to be about a third of the size of the boat’s main rudder to provide good results. Any smaller and it will struggle to steer effectively. The main rudder is fixed in position so that the boat is roughly balanced and the auxiliary rudder then handles the minor corrections required to keep the boat on course. The steering force these systems can apply is limited because they lack any sort of servo unit and they are therefore only able to provide effective self-steering for boats up to a certain size.

Auxiliary rudder systems ideally need to be mounted on centre. Offset mounting compromises steering performance because of the effect of heeling: rudder area that is in the air rather than the water serves no purpose whatsoever! The auxiliary rudder also needs to be sufficiently far back from the main rudder that it is not operating in the latter’s turbulent wash. An auxiliary rudder can be used as an emergency rudder, although having so much less surface area than the main rudder, it cannot be expected to provide more than limited steering if the entire main rudder is lost.

Servo-pendulum systems

A servo-pendulum system uses the power of the water flowing past the hull to generate servo forces that are transmitted to the main rudder via a system of lines. The force available depends on the length of the pendulum arm – the lever on which the water acts – from the bottom end of the rudder blade to the axle around which the pendulum arm pivots (servo force leverage), which is usually about 150-200 cm. Servo-pendulum systems can cope with boats of almost any size: bigger rudders just need a longer pendulum arm to generate the required force. They can only really be used with mechanical steering systems (wheel or tiller) though and do not perform so well with wheel steering systems that have more than 2.5 to 3 full rotations of the wheel from end stop to end stop. Connecting the self-steering up to the emergency tiller rather than the wheel can be an option, but only if the emergency tiller is robust. It is also important that the emergency tiller be within easy reach of the crew on watch, as it must be possible to disengage the windvane and resume steering by hand immediately in an emergency.

Servo-pendulum system on SV Thuriya at the start of the Golden Globe Race

The most convenient servo-pendulum systems for everyday use are those that allow the pendulum rudder to be swung up out of the water easily (lift-up). The system must be quick and straightforward to set up too if it is to be a practical option for short stints at the helm (when the chart table or nature calls, for example) as well as long. The handling disadvantages of traditional servo-pendulum systems are undoubtedly the main reason – along with their rustic looks – that they never became more popular. Although there have probably always been some owners who kept a windvane self-steering system just to cultivate a certain image despite an apparent immunity to the call of the cruel sea, for a long time it was virtually a sure thing that a boat with a mechanical windvane self-steering system on the transom had covered some serious bluewater miles (or was about to).

Manoeuvring in port under engine with a servo-pendulum system installed is only possible with the pendulum rudder raised. The pendulum rudder cannot be immobilised, so any attempt to reverse with it still in the water is certain to end with it swinging forcibly to one side or the other and crashing into any end stops that happen to be in the way. This is the sort of mistake a sailor makes only once.

Modern systems provide a lift-up capability that allows the pendulum arm (and pendulum rudder) to be swung up to one side into a parked position out of harm’s way. Traditional systems, in contrast, require the user to undo a catch or hinge before the rudder can be raised (sideways or aft) out of the water. A servo-pendulum gear will drive a tiller and a wheel equally well provided the boat’s steering system is mechanical rather than hydraulic.

The defining feature of all servo-pendulum systems is the enormous servo force they can bring to bear – sufficient, in fact, to keep a boat of 60 feet and 30 tonnes under control if the transmission lines have a clear run to the helm. All servo-pendulum systems are much more powerful than any auxiliary rudder system – and the right servo-pendulum system installed correctly can steer successfully even at every low speeds and in very light winds. There are Colin Archer replicas in Norway weighing 60 or 70 tonnes that manage fine with a tiller and have no problem using a servo-pendulum system for self-steering. Tensile forces of up to 200 kg are perfectly feasible in such a setting given the right pendulum rudder shaft length (for leverage) and sufficient boat speed. The actual force required to move the main rudder is hardly likely to come anywhere near this theoretical maximum because the crew will invariably shorten sail to reduce weather helm (for context, most human helms judge the amount of weather helm on the wheel or tiller to be excessive when the steering force required reaches more than about 5-8 kg). An experienced skipper knows that too much weather helm is slow and will have no hesitation in calling for a reef or sail change.

Line transfer of Windpilot Pacific on Maxi 33

The transmission lines that link the vane gear to the helm need to be laid out carefully, as virtually all servo-pendulum systems have a maximum travel in the region of 25 cm and therefore cannot afford to lose much efficiency to transmission errors.

Double rudder systems

Double rudder system Windpilot Pacific Plus on SV Adios Labor in Las Palmas

Combining the power of a servo-pendulum system with the independence (from the main rudder) of an auxiliary rudder unites the advantages of both systems and provides the best steering performance of all. The main rudder is fixed in position to balance the boat leaving the double rudder system to look after course corrections essentially untroubled by weather helm. Double rudder systems can deliver effective steering provided the auxiliary rudder blade is roughly a third of the size of the main rudder. Double rudder systems have to be mounted on centre because the servo rudder needs to be in the water all the time. Mount it offset to one side and the pendulum rudder would be left high and dry when the boat heels the wrong way. Wash from the main rudder can compromise the performance of double rudder systems too so it is important to allow sufficient separation between the main rudder and the auxiliary rudder element.

A double rudder system can be used as an emergency rudder.

SV Jonathan a Koopmans 44 in Antartica

Types of Boat

Choosing a boat is often enough a question of faith for sailors. The choice can be heavily influenced by subjective reactions and feelings that frequently have little to do with practical considerations. Errors of judgement made at this stage often become apparent only much later or in particular circumstances such as especially heavy weather. In discussing the various boat types, particular attention is paid – not surprisingly I would suggest – to the features that influence their suitability for use with windvane self-steering.

Long-keelers

Yachts with a long keel hold a course well, are enormously seaworthy and have a strong structure with a robust backbone. The rudder sits at the trailing edge of the keel. The combination of a V-form forefoot and S–shaped frames further aft gives a smooth ride through waves, making this type of boat comfortable and quiet to sail. The daring feats of the unmotorised double-ended rescue cutters designed by legendary Norwegian Colin Archer, which saved countless fishermen in peril on the North Atlantic in the most hideous of conditions, have inspired a legion of fans around the world who continue to admire and enjoy the capabilities of this hull form. Archer’s work also inspired a huge number of other yacht designers and builders and the Archer formula remains synonymous with virtually unlimited seaworthiness. Sailors the world over know exactly what the CA mark means.

SV Lucipara a Buchanan 47

Bernard Moitessier was a fan of this type of design too. His Joshua, which looked set to win him the Golden Globe Race until he decided more sailing was preferable to fame and fortune and carried on to Tahiti instead of returning to Europe and his chance of victory, was a steel double-ender very much in the Archer tradition. Boats almost identical to Moitessiers are still being built under the Joshua name today.

Long-keelers are good at holding a straight course but once they begin to wander, the steering force required to bring them back to the correct heading is substantial because the main rudder is not balanced. This means that effective self-steering can only be achieved with a servo-assisted windvane system or a sufficiently powerful autopilot. Handling a long-keeler at close quarters and in port is not a task for the faint-hearted. Strong nerves, a cool head and/or plenty of big fenders are very much the order of the day!

Whether long-keelers are really safer and more seaworthy than fin-and-skeg designs is a debate that continues to generate much heat as well as light. There is no escaping the fact that being good at holding a course also means being slower to turn, reducing the skipper’s ability to dodge breaking waves in a storm. Long-keelers are generally slower overall too, which makes outrunning bad weather less of an option. The large lateral surface area of the keel prevents the boat slipping sideways in heavy weather too, which may increase the risk of being rolled. The main rudder though certainly enjoys the best of protection tucked in behind the keel and securely mounted from top to bottom with at least three bearings. It has always been – and remains – one of the basic principles of good seamanship that streaming a drogue is the best way to keep a boat lined up with threatening seas in extreme weather. The Jordan Series Drogue (JSD) is probably the most popular option with the global cruising community.

Moderate keel, skeg hunged rudder, Swan 44, SV Rosy Pelican

Fin and skeg

The Sparkman & Stephens design office turned out a great many yachts in the 1960s and 1970s that are now considered to be classics. All old Swan yachts had a long fin and the rudder mounted separately on a robust skeg. The frame pattern was similar to that of the long keel designs and V–shaped frames were used here as well to ensure comfortable sailing, gentle motion and peace down below. These boats were tremendously seaworthy too, but also faster on account of their smaller wetted surface area and better behaved under engine – even in reverse. A long fin is fairly easy to steer since, although it takes relatively little steering force to bring the boat back onto course, the keel still has sufficient surface area to keep the boat heading in a straight line. Boats with the long fin and skeg configuration often have a balancing portion on the rudder blade below the skeg, which helps to make them lighter on the helm than traditional long-keelers. Fin and skeg boats provide ideal conditions for autopilots and windvane self-steering systems. The fin and skeg configuration is clearly the preferred choice of the fleets of sailors passing through the Canary Islands bottleneck every year en route to warmer climes. All the classic cruising boats from Amel, Boström, Bowman, Forgus, Hallberg Rassy, Island Packet, Koopmans, Najad, Malö, Moody, Oyster, Rival, Vancouver, Wauquiez and Westerly fall into this category and consequently work well with self-steering.

The very first grounding, collision with flotsam or storm will be enough to convince any doubters of the significance of the strong skeg and three well-spaced bearings retaining and protecting the rudder.

Deep fin keel and spade rudder

This configuration, which offers higher speeds and just about unbeatable manoeuvrability in harbour, has become very common. The hull frames are U–shaped or trapezoidal in the bow section and wide and flat towards the stern, which is good for length along the waterline and surfing ability but not conducive to a comfortable ride. These boats pound against the water surface rather than carving through the waves, making them noisy and uncomfortable to sail. This will not necessarily matter to the ordinary sailor with more modest ambitions but the difference in comfort can become difficult to ignore on extended voyages if the members of the off-watch are constantly being bounced out of their bunks.

A deep fin keel has a relatively small area of contact with the hull while the spade rudder has no protection and, in most cases, just two bearings to hold it in place: brave indeed is the crew prepared to take on extended bluewater voyages on a boat of this type. Prospective long-distance sailors considering the deep fin option who also value peace of mind would do well to ponder on the fact that there have probably never been more solid objects (not to mention boisterous orcas with a thing about rudders) on, in and under the sea than there are today.

Fin keel boats are easily steered by windvane self-steering systems provided that the windvane is sensitive enough and the transmission system efficient enough to correct any deviation from course promptly. The same goes for autopilots: sensitivity and speed are the key rather than raw power. Extreme yachts that are designed to accelerate rapidly out of displacement mode are too much of a handful for windvane systems (see “The ultimate limits of windvane self-steering”): only the highest specification autopilots with advanced motors and hydraulic pumps have the power and speed necessary to keep them on course.

Centreboard with internal ballast SV Aventura III – Ovni 430

Centreboard or internal ballast

Boats of this design carry their ballast much higher up and therefore have to be relatively wide for stability. This extra width also makes them more sensitive to trim. Increasing heel is almost always accompanied by increasing weather helm, which creates more work for self-steering of any type. The hull is generally of trapezoidal cross-section at the bow, which suggests a less comfortable ride at sea. A number of French designs feature an additional small centreboard or canard in addition to the internal ballast and are easier to trim as a result, but these are almost unheard of outside of France.

Catamaran SV Thalassa, Privilege 465

Catamarans

Catamaran sailors too have the right to close their eyes once in a while. Ocean-going catamarans at sea are almost without exception steered by electric autopilots, with permanently installed inboard autopilot systems generally the preferred way of sparing the crew a life of drudgery. When planning a bluewater adventure, most sailors will want to make effective energy management on board one of their top priorities, but autopilots are among the most power-hungry devices to go to sea, so deciding to rely on one as the primary wheel-or tiller-waggler necessarily involves significant compromises elsewhere on the boat if the batteries are to cope with demand and survive non-motoring hours in good health. Ordinarily the choice of autopilot is guided by the size and weight of the boat: bigger and heavier boats need a more powerful autopilot but more powerful autopilots consume more energy.

Certain of the characteristic features of catamarans are highly conducive to effective steering. Two hulls with a relatively long waterline length and the complete absence of permanent ballast make for very good course-holding abilities, there is relatively little load on the helm and the boat is generally easy to steer (not least because of the efficiency of the stern-mounted rudders). Unlike all but the lightest of monohulls, however, multihulls accelerate rapidly with every puff, pushing the apparent wind a long way forward, and then slow down again quite quickly as the wind drops, causing the apparent wind to swing back aft again. Cruising catamarans are less prone to such dramatic changes in the apparent wind because their design and the amount of equipment they carry inevitably makes them heavier than the stripped-out racers.

Monohulls respond to an increase in wind strength by heeling more and accelerating slightly. The apparent wind goes forward only a few degrees. Multihulls accelerate faster in the puffs with little appreciable heel, causing the apparent wind to go forward significantly. This fundamental characteristic of multihulls has led catamaran skippers to favour autopilots pretty much exclusively. A vane gear though can actually make excellent sense on extended trips, as catamarans can be steered very well indeed by a servo-pendulum system. The boat’s considerable speed potential translates with a servo-pendulum system into significant power at the helm. The system’s windvane can be trusted to provide a reliable steering signal for as long as the wind strength and apparent wind angle remain steady. In variable or gusty conditions, however, the pronounced shifts in apparent wind angle will leave the windvane self-steering system weaving back and forth all over the sea.

Force Transmission to the Main Rudder

Servo-pendulum systems need a smooth-running link to the main rudder to work properly. This will generally not be a problem unless the distance between the two is especially large, in which case the length of the transmission lines and the number of blocks that would be required could create too much friction for the system to operate the two rudders effectively. This problem can be circumvented by parting the mechanical connection between the two rudders. One rudder can then be left connected to the wheel steering system for manual steering and for fine trimming the course when the windvane system has the helm. This means that it is always possible to switch to manual steering straight away if necessary. The other rudder can be hooked up to the servo-pendulum system via transmission lines routed to the emergency tiller. This keeps the transmission lines short and ensures that as much of the force generated as possible reaches the rudder.

Auxiliary and double rudder systems are unsuitable for use on catamarans because the aft beam is too high up to provide the requisite robust mounting position close to the waterline. Not only that, but an auxiliary rudder mounted in this position between the hulls would have no main rudder in front of it to protect it from anything solid that happens to come floating its way.

Windpilot and Autopilot together

Smart sailors can combine the respective advantages of autopilots and windvane self-steering systems by using a small push rod autopilot to operate the pendulum rudder instead of the windvane. The autopilot uses very little electricity, but the powerful servo-pendulum system has no trouble turning the autopilot’s small course corrections into firm and accurate movements of the main rudder.

Combining a small push-rod autopilot with a windvane self-steering system is an attractive option for monohulls because it makes it possible to follow a compass course with very low power consumption. Catamaran sailors have even more to gain from the combination because it enables them to use a Windpilot even in gusty conditions where the boat’s pronounced acceleration and deceleration cause significant variations in the apparent wind angle.

My conversations with catamaran sailors over the years have revealed that all share more or less the same concerns. The suitability of the Windpilot/autopilot combination depends on a number of design features of the boat involved and a few e-mails will usually be enough to bring clarity. It appears that catamaran manufacturers are increasingly choosing to omit a robust emergency tiller system in favour of a screw-down hatch in the deck aft through which an emergency tiller fitting can be lowered and attached to the rudder quadrant in an emergency. A certain amount of structural modification may be necessary in some such cases to ensure reliable (and watertight) force transmission from pendulum rudder to main rudder (indeed a certain amount of modification might be necessary even for owners not considering windvane self-steering just to make the emergency steering arrangement itself properly watertight). More and more bluewater catamarans are taking advantage of the Windpilot/autopilot combination as word spreads of the very significant power savings to be achieved.

Raymarine Autopilot on Windpilot Pacific

A small cockpit autopilot can steer a yacht of 25 tonnes with this arrangement thanks to the steering force generated by the servo element of the vane gear.

When using an autopilot, more powerful self-steering normally means higher electricity consumption, but connecting the autopilot to the windvane system and allowing it to generate the power mechanically neatly sidesteps this issue.

Raymarine Autopilot on SV Westerman

Combined Solution on Monohulls

A small autopilot can be coupled as described to almost any windvane self-steering system.

• If using an auxiliary rudder system, the autopilot is coupled to the small emergency tiller. There is no servo effect with an auxiliary rudder system of course – the autopilot just drives the auxiliary rudder directly – so this arrangement would only be worth considering if there is no way to connect the autopilot to the main rudder (imagine a scenario with a push rod autopilot and wheel steering, for example). An autopilot connected to the emergency tiller will often set up vibrations when motoring because the auxiliary rudder is in the turbulent wash from the propeller.

• The autopilot/vane gear combination makes most sense and is most easily realised with a servo-pendulum system