When it comes to the minimum requirements for the steering gear of yachts, the Recreational Craft Directive 2013/53/EU is so meagre that it could be omitted. Point 5.4 states: "Steering and propulsion control systems shall be designed, constructed and installed in such a way as to enable the transmission of steering forces under foreseeable operating conditions."
Consequently, it does not take much more than the mere presence and satisfactory functioning of a rudder to achieve CE conformity for a production boat. The standard for the most important component of a yacht alongside the hull and rigging comprises a total of just four lines of text. By comparison, the Official Journal of the European Union spends more than four pages on the quality of engines and even stipulates a minimum mileage in addition to exhaust emission limits - 450 operating hours or ten years for marine diesel engines. Nowhere does it say how long steering ropes or rudder bearings should last.
More about the accident:
It is obvious that there is a regulatory gap. A reform of the directive in relation to steering gear is at least being discussed. It is intended to provide much more detailed and concrete specifications and could soon be adopted. Several sources familiar with the process independently confirmed this to YACHT. For the time being, however, the solidity and integrity of the steering system is the sole responsibility of shipyards, designers and fitters - and of the owners when it comes to maintenance.
In recent years, the orca attacks on the Portuguese west coast and in the Strait of Gibraltar have emphasised just how critical the issue is. Dozens of yachts suffer serious accidents every season, becoming rudderless or sinking due to water ingress in the rudder suspension area.
Collisions with flotsam can have similarly serious consequences, especially for boats with twin rudders whose blades are not protected from impact by the keel. This also applies to technical defects or material failure in the steering system, as two recent cases show: this spring, for example, an Arcona 460 sank in the Pacific 300 nautical miles east of the Marquesas Islands after its rudder stock sheared off below the quadrant.
During the Atlantic Rally for Cruisers (ARC) two and a half years ago, a Dutch crew abandoned their X 4.9 because the shaft had come loose from the upper rudder bearing. As with the Arcona, the resulting largely free-swinging shaft caused a crack in the laminate and water ingress, which the sailors were unable to stop in the heavy swell; they had themselves hauled off by an ARC participant who had rushed to their aid. Before abandoning their boat, they switched on the generator to prevent the bilge pump from running out of power. And indeed: a week later, a salvage company was able to tow the "Brainstorm" back to Gran Canaria, which enabled a detailed investigation into the cause of the damage.
The accidents called Niels Jeppesen to the scene, who, as the founder and decades-long designer of X-Yachts, is very familiar with modern series boat construction. "As manufacturers and architects, we have to guarantee the technical safety of the yachts," he says in an interview with YACHT. This applies in particular to such a central component as the steering gear.
Recognising problems at an early stage is difficult
It should be designed in such a way that it "does not become a neuralgic point in the overall system" - especially as the section behind the aft bulkhead is not watertight on most ships and thus quickly threatens total loss, as happened in the case of the Arcona 460 "IdaLina". In fact, this is the pitfall of damage to the rudder: due to the enormous leverage forces, cracks can quickly appear in the hull or the lower bearing, which is immediately associated with considerable water ingress - and this cannot be easily prevented.
"It's difficult for owners to recognise potential problems early on or to fix them themselves," says Jeppesen, who now works for Arcona Yachts and won the title of "European Yacht of the Year" with the Arcona 50 in January. "We all rely too much on the fact that the rudder will hold," he warns.
Unlike the gas installation, the engine or the gearbox, for example, for which regular inspections are common, and unlike the sails, which are always in direct view, there is no "sense of urgency for maintenance" when it comes to the controls. However, there is no room for negligence with such an exposed and safety-relevant system, according to the designer. Jeppesen is not an alarmist. His aim is to convey a fundamental awareness of the problem. He definitely sees a need for action - both on the part of the user and the manufacturer.
If you ask owners when they last had their rudder system serviced or dismantled it themselves, the answer is often whether this is necessary at all. Most leave it to the ritual jerking at the lower end of the rudder blade during winter storage. If there is no major play and the shaft rotates freely in the bearing, then the issue has been resolved.
Spherical roller bearings extremely reliable and durable
In the course of researching this topic, one designer, who shall remain anonymous, even confessed that he had just removed and cleaned the bearings on his own boat - for the first time in more than 20 years. They proved to be impeccable and will probably last just as long.
In fact, the self-aligning spherical roller bearings commonly used today are extremely reliable and durable. As the name suggests, they compensate for skewing as well as slight twisting of the rudder shaft. While plain bearings used to be subject to wear and had to be replaced more frequently, correctly dimensioned and installed roller bearings with spherical bushes are virtually maintenance-free. When removing the crane in autumn, it is usually sufficient to thoroughly rinse the lower bearing to flush out salt residues. However, they must not and must not be lubricated.
Perhaps this is why sailors take the functioning of the control system for granted - precisely because it remains so inconspicuous. Market leader Jefa Marine has been building self-aligning bearings in all sizes and different quality levels for almost 35 years. Many of the best-known shipyards buy from the specialist in Greve, 20 kilometres south-east of Copenhagen. "We have already delivered more than 150,000 bearings," says Jan Faurschou, who, as Head of Sales and Service, is something like the spirit, soul and face of the company. Problems are extremely rare, he assures us. "They are usually due to galvanic corrosion," i.e. electrolysis as a result of poor electrical insulation, for example in the autopilot drive. The aluminium cage of the lower rudder bearing and the rudder stock can then become a sacrificial anode and gradually dissolve. This is one of the reasons why the entire steering system requires regular inspection.
The Danes have dedicated a separate page on their website to this topic and are also proactive when it comes to providing information to their customers. Design and exploded drawings of all components are available online for anyone to access, as are detailed maintenance instructions. However, it is a wealth of knowledge that is of little use if it is not utilised and applied in on-board practice.
Errors during maintenance work can have serious consequences
The response to the accident involving the X 4.9 "Brainstorm" during the ARC shows just how conscientiously Jefa works. Jan Faurschou's team was involved in the case from the very beginning; even when the crew contacted X-Yachts via satellite phone to discuss possible repair attempts at sea, the shipyard called in the technicians in Greve. Although Jefa was not to blame for the technical failure, they modified the assembly process once the investigation report was available.
The case is so revealing because the insurance company ordered a comprehensive analysis of the defective steering gear. The Amsterdam-based materials testing centre Element took a close look at both bearings and the shaft. Their report analysed all possible causes for the rudder shaft slipping out of the upper bearing.
X-Yachts designer Thomas Mielec, who accompanied the investigation as a shipyard representative and inspected the damaged boat immediately after the tow, summarised the results to YACHT as follows: "The experts from Element Materials Technology were able to prove that the upper rudder bearing was originally mounted correctly and that the crucial grub screw for locking the thread was inserted correctly." They even found out the brand and type of thread lock in the spectrometer: Würth Thread Locker Medium Strength. This means that a manufacturing error can be ruled out.
However, the screw connection of the clamping ring, which connects the rudder shaft to the bearing, was later opened and then not correctly secured against untwisting. "There is a very high probability that this led to the accident," says Thomas Mielec. He therefore considers it proven that the error occurred during maintenance work on the rudder bearing of the "Brainstorm", which was carried out by a Spanish service yard shortly before the ARC start.
Redundant solutions make sense
Nevertheless, Jefa boss Jan Faurschou took the incident as an opportunity to mark the head of the grub screw in question - labelled "Fuse 1" in the drawing below - with red sealing wax after tightening. This is intended to signalise to boat builders to either keep their hands off it completely or to proceed with the utmost care when reinstalling it. Owners can also recognise at a glance whether the screw is tight - provided they get close enough to the upper bearing seat. However, this is often not very maintenance-friendly and access to the rudder components generally leaves a lot to be desired.
The connection between the shaft and bearing is just as important as securing the housing, which carries the clamping ring at Jefa. It is made using three horizontal grub screws made of stainless steel, which must be used with grease to prevent galvanic corrosion on the rudder shaft, which is usually made of aluminium.
Jefa recommends not only tightening them to the correct torque (7 Nm for M6 bolts, 35 Nm for M10), but also drilling blind holes a few millimetres deep into the shaft in order to achieve a positive fit in addition to clamping. This is extremely advantageous for stainless steel rudder shafts and at least makes sense for aluminium shafts. Of course, not all shipyards go to this trouble.
Niels Jeppesen would like to see even more care and reliability in the control system, especially in systems where the rudder is only held in place by a screw connection. Some shipyards already offer redundant solutions. Hallberg-Rassy, for example, bolts the shaft not only to the upper rudder bearing, but also to the lower one; if a safety device fails, the shaft still remains in the ship. Hanseyachts takes a different approach for larger models such as the new Hanse 590: The Greifswald-based company mounts the upper bearing in an intermediate compartment and presses the quadrants directly above it onto the shaft so that it cannot slip out.
Far too seldom in yacht building is there another, probably the most effective guarantee against ship loss due to rudder breakage, which would also have given the crew of the Arcona 460 more safety: a stern compartment sealed off well above the waterline. Only a few shipyards offer this - and unfortunately it is not to be expected that the forthcoming revision of the EU Recreational Craft Directive will require it.
Maintenance intervals
- Emergency tiller: The cover can be used to secure the rudder shaft by means of a talje if it has slipped out of the bearing
- Upper rudder bearing: Should be removed and checked every three to five years
- Connection from shaft to bearing: Ensure correct screw connection every year!
- Control ropes made of wire or DyneemaToo much tension puts a strain on the idler pulleys and gearbox, too little tension can lead to jumping off. Check annually!
- Rudder shaft: After uncraning, check for firm seating in the bearings; after soaking, check for ease of movement
- Quadrant: Ensure tight screw connection; annual visual inspection
- Coker: Check for strength and tightness! Replace the neoprene sleeve every seven to ten years
- Lower rudder bearing: See point 2
- Laminate reinforcement: Watch out for cracks
- Rudder blade: When removing the bearings, check the flange to the rudder shaft carefully
Perfect guidance, critical components
How self-aligning spherical roller bearings are constructed and why small grub screws can cause the entire steering gear to fail
While the rudders of yachts were usually guided by simple plain bearings at the beginning of series production, self-aligning spherical roller bearings have become increasingly popular since the 1980s. Due to the elongated shape of the cylindrical rollers, they are also referred to as needle roller bearings. They operate more smoothly and precisely and, if correctly dimensioned and carefully installed, are also virtually wear-free.
In addition to market leader Jefa Marine from Denmark, Lew- mar, Solimar, JP3 and other manufacturers also offer such components. They are largely similar in design; the differences lie in the details, such as the connection between the rudder shaft and bearing.
In Jefa's high-end models, this is a particularly elaborate design. A clamping ring secures the shaft; it hangs on two ball bearings in a housing that is screwed to the actual bushing of the upper roller bearing via a wide flange. This guarantees perfect power transmission and smooth running. However, the four locking screws - three for the shaft and one for the housing of the clamping ring - must be tightened and secured with the correct torque.
This article first appeared in YACHT 20/2024.
