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Know-How: Rigging Emergency Rudders

           The Island Packet Rosinante is towed into port after experiencing rudder problems in the Pacific   

           The Island Packet Rosinante is towed into port after experiencing rudder problems in the Pacific   

We were 1,100 miles from the nearest land when we received a text message on our Iridium GO: “Rudder gone. Water in bilge. Worried pumps can’t keep up. Please call!”

We had been in contact with the owners of Rosinante, a 38ft Island Packet, since they had first announced over the Pacific Puddle Jump net that they were having problems with their rudder. We were only 60 miles from them, so we let them know our position and gave them our Iridium Go number in case they needed assistance. Two days later, they did.

Dealing with a broken rudder mid-passage is not for the faint of heart   

Dealing with a broken rudder mid-passage is not for the faint of heart   

We sailed as quickly as we could to their position, making room onboard in case the crew had to abandon ship. By the time we arrived, though, they had the boat under control and were making headway toward the Marquesas. They were steering with their Hydrovane self-steering gear, but complained they couldn’t hold a straight line. They could see the rudder fluttering around under the boat, seemingly barely attached. Three days later, the gooseneck connecting the boom to the mast ripped off because of the way the boom had been slamming back and forth during the many uncontrolled course changes.

We shadowed Rosinante for 10 days and more than 1,000 miles before making landfall in Hiva Oa, in the Marquesas. While steering with the auxiliary Hydrovane rudder was fraught with difficulty, it is unlikely they could have continued without it.

In the end, the problem was a seized rudder bearing. What the owner took to be the rudder fluttering under the hull was a trick of the waves, while the water in the bilge most likely came from a leaking water tank. There was no evidence of damage of any sort to either the rudder or surrounding material when the boat was inspected. That said, it’s easy for your mind to jump to a worst-case scenario when you’re tired and more than 1,000 miles from land. Whatever the case, the experience impressed upon us the necessity of understanding how a rudder works, how rudders fail and how best to rig up a tried-and-true auxiliary system in the case you ever do lose steerage.

What does a rudder do?

A rudder has two main functions: 1) it is essential for providing lateral resistance aft while holding course, without which the boat would rotate around its keel; 2) it serves to turn the boat when changing course. While the latter feature may seem obvious, the first is often overlooked, which is a big mistake when considering emergency rudder systems.

When you are considering or designing an emergency system, it’s helpful to understand the forces acting on the rudder. The primary force is on the rudder blade, which is created when the blade alters the direction of water flow to port or starboard. The change in momentum of the flow produces a side force, which is then transferred to the bearings or attachment points between the rudder and the boat: either a combination of the rudder stock and the pintles and gudgeons with a keel-hung or skeg-hung rudder; or the stock and rudder bearings with a semi-balanced spade. Note that with a spade rudder, the lower bearing receives the highest load while the upper bearing receives somewhat less.

Technically speaking, a rudder doesn’t turn the boat itself, but rather changes the angle of the boat’s centerline relative to its forward velocity. The resulting pressure (hydrodynamic moment) from the surrounding water then forces the boat on its new course.

To better understand this phenomenon, imagine trying to steer a flying saucer sled. As soon as you impart any resistance to the forward motion of the saucer you start to spin, but don’t change direction. That’s why they are so fun and also so dangerous on steep hills. There must be some element that creates resistance to lateral motion. In the case of a boat it is the shape of the hull, the keel and the rudder all acting together that allow the boat to turn.

When Your Rudder Fails

Unfortunately, no matter how much preventative maintenance we do there are some situations that are simply beyond our control—think hitting a whale, big storms or unseen corrosion—and which could mean you have to manage a worst-case scenario. The fate of the boat can depend on what the issue is with the rudder.

If the bearings are seized, the rudder will at first be difficult to move and then lock up completely. Steerage will be significantly reduced, and it will be impossible to stop the boat from rounding up into the wind. If the rudder is seized to one side, it will try to turn the boat in that same direction. If it seizes along the centerline, the boat can sometimes be controlled with sail trim as its aft lateral resistance is still in place.

If you lose a rudder completely—for example, 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-the-counter 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 drogue-style 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 rudder to react to alternating wave loads. A rudder system with a lashed tiller will inevitably experience much higher peak load than a rudder steered by hand.

The second of Kamen’s ideas is the “Finned Steering Oar,” which has the advantage of being comprised of parts that can be scavenged for free from almost any windsurfing club: including a pair of obsolete windsurfer masts and from two to six old centerboards. To get started, lash the two masts together, trim the ends to suit and bolt a pair (or several pairs) of opposing fins to the blade end. Add a PVC T-handle to the handle end, and the finned steering oar is ready to go. The only things you need to buy are nuts, bolts and some short pieces of PVC pipe.

Those who have tried to steer a yacht of any size with a conventional steering oar will be well versed with the problem inherent in this kind of system: specifically, that the handle-force to blade-force ratio is about one-to-one. As a result, you simply can’t push with nearly enough force to effectively steer a boat much bigger than around 28ft, even in smooth water.

The key to Kamen’s Finned Steering Oar lies in the fact it is controlled by twisting it around its long axis, instead of displacing an oar handle side-to-side like a tiller. Doing so introduces a healthy angle of attack on the blades and creates enough lift to move the boat, without translating this force directly to the person at the helm—an elegant solution to the problem.

Steering in an emergency

Whatever emergency system you decide on, you can be sure it won’t work as well as the primary rudder. However, there are a few things you can do to make steering with an auxiliary rudder more manageable.

• Reduce speed to reduce the loads on both the rudder and the boat as a whole. Reef the sails and consider towing a drogue. Avoid surfing down waves. Expect to go a third to half the speed you would with a full rudder.

• Make sure you have a balanced sail plan. Your balance will likely be different than sailing with the primary rudder due to the lack of lateral resistance aft. Balancing the boat for the point of sail might also require moving some weight around to change the center of lateral resistance.

• If you’re sailing on a run, it is helpful to move the center of effort forward to keep the bow pointed downwind. Twin jibs on a forestay are the best option, while in heavier conditions it is a good idea to sheet in a storm jib or working jib flat on the centerline. It can also help to move some weight aft, or even tow a drogue.

• When close-reaching, you may have to significantly reef the main, while keeping a full headsail to reduce the weather helm.

• Expect your heading to oscillate up to 60 degrees. There may be little you can do about this, except to hold on and adjust your rig and helm when possible.

• If the original rudder is hindering your steering or making it impossible, it may have to be removed.

Although lost rudders have been responsible for many vessel abandonments and are one of the scariest things that can happen at sea, with the right knowledge and preparation, the situation can be managed. And while you may not sail as well as with your original rudder, an emergency rudder system will at least allow you to get the boat safely to where you can make repairs. 

This rudder sustained serious damage in the course of a hard grounding off Fiji 

This rudder sustained serious damage in the course of a hard grounding off Fiji 

Rudder damage: key points

There are five main ways that a rudder can break and cause a boat to lose steerage.

1. Rudder stock failure: The rudder stock sometimes fails when bending stress in the stock exceeds the strength of the material. With a spade rudder, this usually occurs just below the lower rudder bearing, at the point of maximum bending load.

2. Rudder blade detaches from the stock: The blade can detach from the stock as a result of sudden impact, delamination or welds corroding through. Rudders are often built by welding some pieces of stainless steel perpendicular to the rudder stock. Foam is then laminated on either side of these “tangs” and fiberglassed over. With time, stagnant water in the rudder can cause the stainless-steel welds between the tangs and the stock to fail.

3. Bearing/bushing failure: Bearings can break down over time, especially in steel bearing systems when seals fail and saltwater gets into the bearing pack. Delrin or other plastic-type bushings can also break down over time through material degradation or undue friction. If a bearing/bushing fails, the rudder can seize completely and/or tilt and bind, depending on your course and angle of sail.

4. Rudder binding: Rudder blade binding is typically caused by fish nets or lines that become wedged between the rudder blade and the hull.

5. Hull deformation or cracking: In some rare cases, rudder failure may be caused by hull deformation or material failure around the rudder bearing mounts. While the least common failure mechanism, it is also the most difficult to repair.

Of course, the best emergency rudder system is the one you never use. So, given these failure mechanisms there are a few things to check to make sure the rudder is in good operational order. These include looking for:

• Pitting, cracks or corrosion of the rudder shaft at joints and especially where it enters and exits the hull

• Moisture in the rudder blade material: use a contact moisture meter or drill a small hole in the rudder blade and check for water

• Cracks or crazing on the surface of the rudder blade, which could suggest hidden flexing of the rudder post

• Any damage in the bearings or gudgeons, including the pintles at the foot of a non-load-bearing skeg

• Cracks or deformation of the hull around the rudder, including cracks in the bottom paint or gelcoat, since these could be a sign of more severe problems

• Movement or deflection of the blade, shaft or bearings when the rudder is pushed in any or all directions

           A Monitor self-steering system (left); and the SOS Rudder (right) both from Scanmar   

           A Monitor self-steering system (left); and the SOS Rudder (right) both from Scanmar   

Emergency Rudder Options

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-the-shelf system is adequate for your needs.

           A Hydrovane steering system on the hard   

           A Hydrovane steering system on the hard   

Hydrovane: This windvane system has an independent rudder to control the boat. There is no additional setup to convert to an emergency rudder. (

Scanmar SOS: Can be used as a stand-alone system or modified to work with the Monitor windvane assembly. (

Windpilot SOS Rudder: This can be used as a standalone system or in conjunction with the Windpilot windvane. (

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. (

Cape Horn Emergency Rudder: Works with the Cape Horn self-steering system and attaches directly to the self-steering gear through pintles and gudgeons. (

Seabrake and Delta Drogue: These systems function by dragging a drogue-style 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. (

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. (

           The Hydrovane as a backup in the Marquesas    

           The Hydrovane as a backup in the Marquesas    

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.

  The SOS Rudder before being deployed (left); Windpilot’s SOS Rudder (right) features rugged construction

  The SOS Rudder before being deployed (left); Windpilot’s SOS Rudder (right) features rugged construction

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 ( 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.

Photos courtesy of Paul Kamen; illustrations by Robin Urquhart

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. (

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. (

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 (; 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

Photos by Robin Urquhart

March 2018


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