Installation in steel hulls

General installation issues:

The most important installation hint is: NEVER PUT ANY GREASE BETWEEN THE ROLLERS

  • In steel hulls one should use a stainless steel rudderstock. Due to the insulating construction of the Jefa bearings and the mounting method there will be no electrical connection between the hull and the bearing and the bearing and shaft. This method will make sure there will be no electrolysis. (Please have a look on our electrolysis page).
  • We advise to only use self-aligning type roller bearings as this will make the installation very easy and will guaranty a good functioning end result.  Standard (non self-aligning) bottom bearings can only be installed by glueing them in a rudder tube in combination with the rudder stock mounted in the vessel, a time consuming and costly operation. As the tolerance between the bearings and shaft is only a couple of hundreds of millimetres, one can’t afford any misalignment between the bearings and rudder shaft. 

Our suggested mounting procedure for Jefa rudder systems in steel hulls:

  1. After the turning of the hull and the joining with the deck locate the rotational axis of the rudder. Align and cut the hole for the steel bearing tube. The inside diameter of the tube should be a couple of millimetres bigger than the outside diameter of the bearing housing. Try to extend the bearing tube as high as possible above the waterline but at least more than 100 mm above the final waterline. (If you have any doubts, please consult our sealing system page). Please note that when the top of the sealing system is underneath the waterline, a potential dangerous situation is created and an alternative steering arrangement should be considered. Align the tube a good as possible to the future centreline of the rudder shaft and weld it in the hull.
  2. Grind and clean the inside of the bearing tube and outside of the bearing housing. Close the top and bottom surface of the bearing with some plastic and tape, so no glue could run into the bearing. Put the bearing in the tube and align it using small wigs. Put a small fillet of epoxy filler around the bottom of the bearing. After the epoxy filler has hardened, cast the area between the bearing housing and tube with for example thin epoxy resin.
  3. Cut the hole for the top bearing in oversize, so you will have some adjustment for the alignment of the rudderstock. 
  4. Remove the key, if present,  out of the keyway as it could damage the rollers. Don’t forget to put the gaiter over the tube as there will be no possibility any more to mount it.  
  5. We are now ready to slide the rudder shaft into the boat. Run the rudder stock carefully, while rotating, up into the top deck hole. Secure the rudder blade in position and slide the top bearing over the shaft while rotating. If the angle of the mounting surface of the top bearing is more than a couple of degrees out, produce a wig (teak or delrin) to adjust the top surface angle. 
  6. Carefully align the rudder to it’s theoretical position using wigs between the top bearing and the holes in the hull. Please note that if the keel isn’t at its optimal angle under the ship it could be wise to also misalign the rudder to accommodate the same angle as the keel, as every misalignment between the rudder and keel will be very obvious when standing behind the ship. 
  7. Drill the appropriate holes for the top bearing. Remove the bearing, clean the bottom on the flange and deck and put a proper film of polyurethane sealant underneath the flange of the top bearing. If your rudder system doesn’t consist of self-aligning bearings it’s very important to not just bolt down the top bearing on the deck as the surface of the deck and the flange of the bearing will always be misaligned a bit. One can use the sealant to adjust for this small misalignment. Tighten the bolts lightly, just as far as the sealant starts to be pressed from underneath the flange. Wait at least 24 hours for the sealant to harden, before you finally tighten the bolts permanently. If a self-aligning type of top bearing is used, one can tighten the bolts permanently as the bearing will align itself to the rudder shaft. 
  8. The final part of the installation is the sealing system.
    The gaiter should not be installed completely stretched out. The distance between both jubilee clips should be between 50 and 70 mm. Please make sure the rudder is in the amidships position when tightening the jubilee clips. After the rudder stops have been installed, one should check if the gaiter allows to rotate the rudder to both end positions without being stretched. If the ship is intended to make a long world tour, it’s advisable to purchase an extra unglued gaiter with a tube of neoprene glue. This way one can replace the gaiter quick and easy, without having to drop the rudder.
  9. Now the vertical locking can be installed. There are two ways of vertical locking: A rudder head or locking ring on top of the top bearing and the use of a top bearing with an integrated vertical roller bearing (type 4….Z). The second option will give extra advantages in this application as it also provides a vertical locking upwards.
    In both cases one should use grease or anti seize paste on the tread of the set screws of the locking rings, especially when used above deck. Tighten the screws when the shaft is at the correct height. Remove the screws, drop the shaft a bit, and drill a small hole a few millimetres deep so the set screws will enter the shaft a bit. This will make sure that the rudder will never drop down.

We hope these guidelines will provide a trouble free installation of the Jefa rudder system. If you have questions or problems please mail them to us at