MRUDMonitor Emergency Rudder
Our challenge was to be able to convert the Monitor aboard a 50 foot BOC boat, in the roaring forties, into a true emergency rudder. We knew that the strength required for survival in these conditions would guarantee a more than adequate back up system for cruisers having the misfortune to lose their boats rudder. MRUD has been designed to meet the following criteria:
- Strong and dependable
- Reasonably easy to install at sea
- Easy to store on board
MRUD offers a unique solution to a serious problem. Download MRUD Brochure
In Heavy Weather Sailing, by Adlard Coles the author remarks, "Breakages of rudders are almost as common as breakages of masts." The Monitor has survived the toughest oceans in the world, sailed through seas and weather which would qualify as a cruisers nightmare and kept on steering.
The BOC is unparalleled as a test of equipment. The BOC boats not only round Cape Horn, they stay in the Southern Ocean lower latitudes for several months of brutal weather and towering seas. MRUD was developed with these conditions in mind.
The MRUD Conversion Kit
Finally, a solution to the nightmare of losing your boats main rudder.
Many attempts have been made to make individual emergency rudders. The majority require very expensive custom engineering and manufacturing. Excessive weight and size make these custom rudders difficult to store and install at sea, and, even so most have questionable performance and reliability.
The beauty of the Monitor MRUD system is that it uses the regular Monitor servopendulum system which is converted to an emergency rudder. The standard Monitor mounting system is extremely strong because it has four stainless steel mounting tubes that are spread apart to distribute the load over a larger area. If the mounting tubes are long, diagonal tubes are added for additional strength
Half the emergency rudder problem is the method of attachment. With the Monitor in place the attachment system is already there! The Monitor mounting system is strong enough to support a large, rigid rudder.
The Monitor MRUD is highly efficient because it has a high lift NACA profile and because it is located behind the boat. The size of the emergency rudder can therefore be smaller making it more practical to store and to mount, yet still large enough to steer a 50 foot boat.
The Monitor principle works on the boats own rudder rather than using an auxiliary rudder/trimtab system like our own auto-helm windvane. Such systems can be used as emergency rudders, but they are not in general the best principle for normal self steering.
If a boat experiences weather that is bad enough to break the boats main rudder those conditions are probably bad enough to do severe damage to an auxiliary rudder type of self steering. The damaged main rudder can also damage the auxiliary rudder. The servopendulum gear does not have this problem. It has the ability to move to the side, out of the way, and it has an easily replaced safety tube in case of an overload situation.
We prefer to use the best principle for normal self steering, (servopendulum) and in the unlikely situation that the boats own rudder is broken, the strong, stainless steel MRUD can be mounted at sea and steer the boat to safety. You can steer by hand by moving the counterweight from left to right, by using the regular Monitor airvane or by hooking up a small inexpensive autopilot to the Monitor counterweight.
A pin with a cotter ring holds the servo paddle which is removed and replaced by the much larger emergency rudder assembly. The stainless steel rudder is foam filled for strength and flotation. The hinge has a special tapered hinge pin to make it easier to mount at sea. The pendulum is locked and supported by a wedge between the pendulum and the strutguard. Spectra lines add extra support for front and side loads, just the way a mast is stayed.
The MRUD is similar to your life raft. We hope that you never have to use it, but if you do it will be the most important piece of gear on board.
Can you afford to be without it?
A boat without a rudder is a serious matter and these instructions are intended to make sure that your MRUD is understood and used properly in the event of rudder failure on your boat.
We strongly recommend that you fit MRUD to your Monitor before you leave on your next long cruise and even use it on a short test sail. Should the installation become necessary, you may be in rough seas. If you practice putting MRUD on in port, it will be much easier to repeat the installation later at sea.
Your MRUD assembly contains:
- Complete hinge assembly
- Safety tube and spare
- Special tapered hinge pin
- Pendulum wedge with cross-bolts
- Upside down lowers- Spectra line
- Upside down uppers-Spectra line
- Stainless steel Emergency Rudder
- Bolts for clamp tubes
- Storage bag with attachments for hoisting
When you transform the Monitor to a much larger, rigged emergency rudder the loads are greatly increased and you should make sure that your Monitor is mounted as follows:
The Monitor mounting brackets do not normally need backing plates. If your boat is a light weight core construction you might need them. If in doubt consult the factory.
Since 1991 all Monitor units built have strutguards. This protective bumper goes behind the pendulum and connects the legs of the main frame with each other. It also makes the main frame a lot stronger. Older Monitors did not have the strutguard but it can be retrofitted. With the use of MRUD the Monitor has to have a strutguard because this is where the wedge that holds and supports the pendulum is placed.
Test the fit of the wedge
Place the wedge between the strutguard and the pendulum. There might be some variation in the fabrication and location of the strutguard. Lock the wedge in place with the supplied crossbolts or locking pins.
Through bolt Clamp Tubes (only on old Monitors)
The lower mounting tubes are attached to the frame with clamp tubes that are attached to the bottom of the frame legs. To be absolutely sure that the tubes cannot escape from the clamp tube both fittings should be through bolted with small stainless steel bolts (included).
The Monitor frame is attached to the hull in four places. With longer mounting tubes we sometimes add same side diagonal tubes which make the installation tremendously strong. With the use of MRUD some installations should add diagonals. Consult the Monitor factory for advice.
The entire MRUD assembly is stored in a safety colored orange bag marked "Emergency Rudder."
Mounting and operation of the MRUD at sea
Heave to with the boat and try to avoid forward movement. Wear your safety harness.
- Disconnect Monitor pendulum lines from the tiller or wheel adapter and lock the pendulum in the middle by taking the lines to a cleat.
- Lock the wedge in place with the supplied cross-bolts or locking pins. Secure it with lines that are attached to the wedge.
- Remove the servo paddle assembly by removing the cotter ring and the hinge pin. Store the servo assembly.
- Attach MRUD assembly to Monitor. This can be done in different ways and it should have been practiced at the dock. One way is to hold the paddle upside down with the help of the attached lines when you put the special tapered hinge pin through the hole in the hinge block. The pin is attached to the hinge with a safety line. When the pin is in place the cotter ring is used to keep the hinge pin in place. Another method to attach MRUD is to let it float behind the Monitor while the hinge pin is put in place. Use at least one spectra line as a safety line.
- Secure the "upside down lowers." These are the spectra lines that are attached around the shaft of MRUD. The lines have a bowline with a tail close to the rudder blade. This tail line should go around the corner of the strutguard where it is welded to the leg of the frame. The line should then go down to the bowline and then up to the strutguard again. By running the line back and forth you have now a very simple and practical "block and tackle" purchase system. The spectra lines will stretch very little and you have an easy system to make the lines tight. Do the same thing with the opposite "upside down lower." The lines that go through the emergency rudder with a knot on each side are called upside down "uppers" and it depends on the boat where you attach them. They could go to the frame in the same way as the "lowers", but you might be better off leading them to a cleat or a winch on deck. You have now secured the pendulum with the wedge and the spectra lines are supporting the rudder the same way your mast is supported with uppers and lowers-only this "mast" is upside down. Check for chaffing in the spectra lines after use and add or replace lines as necessary.
Your Monitor now has a very rigid and strong spade rudder ready to steer your boat. Of course you need to balance your boat carefully and possibly reduce sails somewhat. Compared to your boats rudder you may feel that the MRUD is too small to control your boat. However, we have purposely kept it this way (will not break, easy to store, easier to install, etc.). With a normal boat there are very small corrections with the rudder unless you carry too much sail or have ignored balancing the sail plan. The large size of the boats main rudder is necessary for maneuverability which is needed when you dock the boat or are on a race course. With MRUD in the open ocean and a course to steer you can make slow corrections. At your destination you can anchor or get help for the last few miles if you feel that you cannot maneuver in tight corners.
Three methods of steering
- By hand: Grab the counterweight and move it. You are now steering by hand. You can rig up lines to the counterweight and steer from any position on the boat.
- With regular Monitor airvane: Your Monitor will now work as an auxiliary rudder self-steering windvane. The spectra tension lines provide some friction. You might find that the performance improves if you ease the spectra lines just a little bit if conditions permit.
- With a small autopilot: A small tiller pilot can be rigged up to the counter weight. The tiller pilot will steer a magnetic compass course.
"In 2003-2004 we sailed from the UK, around South America and back - a logged distance of 20.000 miles. Most of this trip was under sail and we used the Monitor self steering for most of the time. We lost our [boat's] rudder in the South Atlantic halfway between Estrecho de Magalles and Buenos Aires.The MRUD was rigged and steered us the remaining 500 nm to Mar del Plata in Argentina. We could, literally, have been lost without it."
Quote from e-mail received from Robin Davies, Around Alone particpant four times:
"Leg 1 is over, South Carolina arrived in Capetown without a rudder, and what will be documented is that the 2300 miles I sailed without a rudder are without a doubt the most difficult and demanding 2300 miles I have ever sailed - or ever want to sail.
"It was a far more difficult proposition than my 2500 mile jury rig sail in the southern ocean around Cape Horn to the Falkland Islands after my leg 3 dismasting in the 1994-95 BOC race.
"MRUD was a very significant part of my emergency rudder system, and without it - in so far as it was a piece of kit that should have been tried and tested beforehand - not left to the time of the emergency to use.
"I can only strongly recommend that all MONITOR users going offshore take the MRUD system as there (sic) emergency steering system, it will without any doubt get them into port should the ultimate mishap of broken rudder occur. I would strongly recommend they try it out beforehand."