EMERGENCY RUDDER OPTIONS
How to choose and install the right electric windlass for your boat By Sam Fortescue
There are a number of commercially available emergency steering systems, as well as some self-steering systems that can function as backup emergency rudders. Critics of windvane-type emergency systems usually focus on the size of the auxiliary rudder. As with any system, however, the rudder must be adequately sized to control the boat in a large sea state. Engineering analysis provided by the manufacturer or designer can determine whether an off-theshelf system is adequate for your needs.
Hydrovane: This windvane system has an independent rudder to control the boat. There is no additional setup to convert to an emergency rudder. (hydrovane.com)
Scanmar SOS: Can be used as a standalone system or modified to work with the Monitor windvane assembly. (selfsteer.com)
Windpilot SOS Rudder: This can be used as a standalone system or in conjunction with the Windpilot windvane. (windpilot.com) Fleming Global Auxiliary Rudder: This windvane system incorporates a servo mechanism to control the main rudder. The servo, in turn, can be disengaged to serve as a standalone device in the case of main rudder failure. (flemingselfsteer.com) Cape Horn Emergency Rudder: Works with the Cape Horn self-steering system and attaches directly to the self-steering gear through pintles and gudgeons. (capehorn.com) Seabrake and Delta Drogue: These systems function by dragging a droguestyle device astern. Steering is accomplished by shortening lines attached to a bridle to pull the drogue closer to one side of the boat or the other, thereby increasing drag on that side. (seaanchor.com) Oceansteer: This is a relatively new product on the market and consists of a large floating rudder-like device that drags directly behind the boat. Lines to either side rotate the device to create a rudder effect. (oceansteer.co.uk)
As with the commercially available systems, there are also a variety of different emergency rudders that can be built either ahead of time at home or at sea. While the commercial systems are well-engineered, they are not boat-specific. Building your own rudder, or having one built, on the other hand, will ensure that it is designed for your particular boat, taking things like weight, speed, balance and attachment location into account.
No matter if you build it in a garage or following a catastrophic event at sea, there are a few general principles to follow for any rudder. Obviously, it is not only better to build an auxiliary rudder on land, but to try it out in a controlled environment to see how it performs. Unfortunately, not everyone will do this, and will be setting up their emergency system for the first time only after the primary rudder
has failed. Either way, there are a number of general design guidelines you should follow. First and foremost, in terms of size and strength, a rudder system must be designed for expected loads plus a safety factor. Determining the loads is relatively easy with formulas published online or in reference books. Design strength is especially important for blade-style rudders. The rudder must also be large enough that it can control the boat in a wide variety of conditions and angles of sail.
Another requirement for any good emergency rudder system is that it be easily deployed. The conditions in which any emergency rudder becomes necessary will likely be difficult, to say the least; it may, for example, be impossible to line up attachment points in a seaway with no directional stability. With this in mind, the easiest emergency rudder systems to deploy are cassette-style, where the rudder drops in like a daggerboard, or swing-style, where the rudder swings down and locks into position.
Antrim Associates Naval Architects (antrimdesign.com) provides some general guidelines for constructing a blade-style auxiliary rudder. These include the following: • Draft, at minimum, should be half that of the original rudder
• Area, at minimum, should be half that of the original rudder
• The thickness of the foil should be substantial for strength
• A rough surface is OK as it creates more resistance
Antrim also provides free plans online for auxiliary rudders for boats of various lengths, including up to 27ft, up to 35ft, up to 43ft and up to 50ft.
Another good source is the emergency rudder guidelines for the Pacific Cup Race published by naval architect and Singlehanded Transpac veteran Paul Kamen. He provides material specifications and formulas for determining the strength of the rudder elements for a blade-style rudder. Using Kamen’s guidelines, in turn, will ensure a rudder is adequately sized for an individual boat, although they do require good math skills. (pacificcup.org/kb/emergency-rudder-design-guidelines)
Veteran solo sailor Rob Macfarlane, who holds the distinction of being the first person to finish the last 500 miles of the TransPac with an emergency rudder, also provides clear direction on the design and construction of an auxiliary rudder in a presentation to the Singlehanded Sailing Society available online. (bluemoment. com/emergencyrudders.html) if the shaft shears off on a semi-balanced spade and it becomes completely detached—you can expect even more dramatic results. The boat will no longer track controllably and will rotate around the center of lateral resistance, usually the keel. For a fin-keel boat the rotation will be especially rapid and abrupt. If the sails are up, the rapid turn can even develop into a broach.
Should either of these things happen, it’s important that you stay calm, make sure the crew is clipped in and that no one was thrown overboard or seriously injured in the mayhem. Next, drop all sails and get the boat under some semblance of control. If you were motoring, throttle back to neutral. In some cases, just dropping sails and/or idling in neutral may be enough. Some experienced sailors recommend raising a working jib and sheeting it in hard to stabilize the boat’s motion. Others recommend deploying a sea anchor to keep the bow pointed into the wind and waves, and reduce motion, especially any backward sliding on larger swells.
Once the boat is under control, you need to check for damage. First, check to see if the stock is still in the boat—if it is not, there will now be a big hole in the hull that needs to be plugged— fast! You should also determine whether the structure around the stock is still in one piece. If there was a significant shock load, such as with a hard grounding, the stock may very well have damaged the surrounding hull.
Check the bilge for water and deal with any leaks as soon as possible. It is also a good idea to check the rudder under the water to see what condition it is in—a GoPro on a boathook is a great way to do this. Once you’ve gathered all the relevant information and made the boat safe, you can start to think about next steps. If you’re close to port and it’s shallow enough, anchor and call for assistance. If you’re offshore on your own, though, or in a position that requires the ability to steer before assistance can arrive, it’s time to deploy an emergency rudder.
TYPES OF EMERGENCY RUDDERS
Among the most rudimentary types of emergency rudder is the drogue-style, which employs the same principle as the over-thecounter Seabrake and Delta Drogue (see sidebar “Emergency Rudder Options”), but can be made relatively simply from materials onboard. A man-overboard drogue works best, although sailors in the past have used cabinet doors, old tires or even seat cushions and chain. The point is to get something dragging behind the boat that will neither sink nor skip on the surface.
The rest of the system is comprised of a spinnaker pole lashed horizontally across the transom, lines running along either side of the boat to form a bridle, and a length of line between the bridle and the drag device. Turning is accomplished by shortening the line on the side you want to turn toward, usually with the help of a winch. This pulls the drag device over to that side of the boat causing the angle of the boat to change, similar to how a rudder works, but without the lift force.
A drogue-style drag device is also often used in conjunction with a blade-style emergency rudder to bring the center of lateral resistance aft. Even if it is just dragging behind the boat and not being manipulated for turning, it will help the auxiliary rudder do its job. Another benefit of a droguestyle rudder comes when a rudderless vessel is under tow in a swell. The drogue will keep the tow line taut and avoid shock-loading the tow line.
Another emergency rudder option is a steering oar, which due to its simplicity, is the most common type of emergency rudder to be constructed at sea. However, it is also the least effective. Typically, it relies on a spinnaker or whisker pole with one end lashed to the transom or backstay and the other bolted to a cabinet door, sole panel or some other piece of flat stock. Lines are run from the rudder end of the spinnaker pole back to cockpit winches, so that cranking in on one or the other of the lines turns the boat. The end of the spinnaker pole attached to the flat stock in the water should also have a good amount of chain or dive weights attached to keep it submerged.
Again, it is a simple system. However, it tends to perform poorly because of the forces involved relative to its construction and is recommended only for boats less than 30ft long.
With an eye toward improving on these two options, naval architect Paul Kamen has developed two alternative emergency rudder systems that have proven to work on boats up to 50ft, and which employ a combination of lightweight materials, construction simplicity and stowability, making them worthy of further exploration.
The first of these is the “Soft Rudder,” made of sailcloth and two spars serving as a mast/ rudder stock and a boom/tiller. One of the nice things about this design is that it gets a lot of rudder area under water all the way aft where you need it for directional stability.
With the Soft Rudder, a professional sailmaker should build the sail part of the system before you cast off lines and include a luff pocket (like a Laser sail) to go around the “mast” or rudder stock. When doing so he or she should leave some extra room in the luff pocket so that it forms a streamlined shape around the spar, making vortex-induced vibrations less likely. Include battens to allow some roach and to help suppress underwater luffing.
The Soft Rudder also requires a line corresponding to a boom vang to keep the leech tensioned and prevent twist in the “sail.” Beyond that, instead of gudgeons and pintles, all you really need is a strong padeye in the transom as low as possible (off-center is OK too if access is difficult) and another attachment point as high as possible, like the stern rail or a strut or cable running between the two quarter-pulpits if no continuous stern rail exists.
When deploying, you can pre-lead the “gudgeon lines” tied to the mast/rudder stock through the two attachment points on the boat and then use them to haul the spar into position, which helps eliminates the problem of deployment in a seaway. Be warned, though, these gudgeon lines may start to chafe in as little as a few hours and will need to be checked. That said, remember, all we’re trying to do is get home, not win the race. It’s OK if you have to make frequent repairs as you go.
Bear in mind that if you are using a spinnaker pole as a tiller, it is designed primairly as a compression member and may prove to be susceptible to bending. Therefore, limit the load by hand steering the tiller/boom, since this 1) limits the input torque to what a human arm can apply (times the deliberately short tiller length) and 2) also allows the
Robin Urquhart is a freelance writer and has a Master’s in Building Science Engineering; he is currently cruising the South Pacific with his wife, Fiona, aboard their 1979 Dufour 35, Monark. Rob Macfarlane and Paul Kamen both contributed to this article as well. Rob is an accomplished offshore solo-racer and is currently sailing the South Pacific aboard his Morgan N/M 456, Tiger Beetle (tbeetle.wordpress.com); Paul is a naval architect and professional engineer in Berkeley, California, specializing in small craft accident forensics. He has navigated 21 races to Hawaii, and designed and built many emergency/backup rudders. His own boat is the Merit 25, Twilight Zone, which he sailed round trip to Kauai and back in the 1986 Singlehanded Transpac
Every sailor appreciates a little mechanical assistance up at the bow. At the same time, whether you’re upgrading the boat with a new windlass or speccing a new boat, it’s an expensive decision that you need to get right the first time. The first and often most baffling question is whether to opt for a windlass that works on a horizontal or vertical axis—or as Jim Thomas, windlass specialist at marine hardware distributor Imtra, puts it, “Ferris wheel or carousel?” Luckily, this is much more straightforward than it appears. The vertical windlass has a number of key advantages over its bulkier, more traditional alternative. First and foremost, the motor and gearbox assembly is mounted out of sight and out of the way under the deck, freeing up valuable real estate at the bow. In addition, the motor can usually be offset to one side or the other to help fit the chain locker. The way the chain is fed round the gypsy and into the chain pipe means that this orientation of windlass also grips more links of the chain simultaneously, giving a more secure lift.
On the other hand, older or smaller boats with limited space in the anchor locker may benefit from installing a horizontal windlass. With the motor housed in the deck unit, there’s more room for stowing chain below, and being higher off the deck, a horizontal model may offer a cleaner run of chain or rode over a high toerail. This extra height also offers a greater fall of chain into the locker below. That’s important, because it is gravity that stows the chain, and that requires at least 15in of fall between the capstan and the top of the heaped chain. The extra height of the capstan of a horizontal windlass should win you anything from 6-12in extra.
That said, as the chain connects with only about 90 degrees of the gypsy in a horizontal installation, the angle at which it is fed onto the windlass becomes crucial. You can improve the performance of the unit if you can angle the chain slightly up from the bow roller. However, Thomas warns against deflecting the chain as it falls into the locker since, as he puts it, “Every redirect creates friction, which means amps spiking and breakers tripping out.”
Beyond that, it is easier to maintain and service a traditional horizontal windlass, because its key components are all above deck. Most windlasses of either type are offered with an optional rope capstan, a useful feature.
PULLING POWER
Having decided on the orientation of your windlass, you must decide how powerful you need it to be. Many manufacturers offer a quick guide that equates boat size with windlass power, but while this may work in many cases, it is not the full story.
Power should be determined by the maximum force you need the windlass to exert in order to retrieve the anchor. This so-called “pulling power” is measured in pounds and refers to the force that the windlass can bring to bear in its first few seconds of operation to break out the anchor. Its “working power,” or the amount of power it provides over a longer period of time, will typically be much lower.
Although you can use a boat’s service batteries, some sailors install a dedicated one sited close to the windlass. A big motor can draw a peak current of more than 200A when it starts under load, calling for very heavy (and therefore expensive) copper cabling to avoid voltage drop. If your cables are too small, the windlass’s performance can not only be reduced, but there is a real possibility that the cables may overheat.
That said, systems expert (and regular SAIL contributor) Nigel Calder maintains such remote batteries aren’t a universal solution. “The draw of the windlass pulls down the voltage on the bow battery, at which point the alternator goes to full output, so you need sizeable cables between the aft battery bank and the bow battery. These cables will not be much smaller than if you power the windlass from the house bank in the first place, so there is little cost saving in the cables and you get the extra weight of the battery in the bow.”
Calder adds that the voltage drop over the long cables often results in a poor charging re- gime for the bow battery as well. One way to facilitate the use of smaller (and thus cheaper) cables while ensuring the bow battery remains optimally charged is to install a DC batteryto-battery charger such as those made by Sterling Power.
Once you’ve sorted out your power supply, the next step is to select a control system for the windlass. The sky is the limit here—from simple foot buttons to multiple control units incorporating chain counters and even automatic anchor recovery. For the simplest system, opt for a pair of high-amp foot buttons by the windlass that can be wired directly between the battery and the motor. This keeps the number of electrical components to a minimum while also freeing up the user’s hands to deal with chain.
Most people these days prefer a remote control plugged into a socket in the chain