Type 4 self aligning rudder bearings

The Type 4 bearing is a spherical roller bearing and was specifically designed for use with Composite or Aluminum rudderstocks.

Being a spherical roller bearing this allows the bearings to self align and turn whilst under load maintaining low steering friction.

The bearing features an aluminum inner race supported by up to 3 rows of Ertalyte® or Peek® barrel shaped rollers.


The rollers and inner race assembly are fitted within a spherical outer housing.


Seal housings are fitted above and below the main bearing races to make the assembly watertight.

  • Type 4 bearings can be used as upper and lower bearings.                                              
  • Bearings are available with 1,2 or 3 rows of barrel rollers to match rudder loads and bearing safe working loads.                                                         A lesser number of rows will mean a lighter bearing.
  •   The barrel shaped rollers and spherical outer housing allows the bearing to self-align while the rudderstock rotates within the bearing.
  •   Outer housings and inner races are machined from solid marine grade aluminium.
  • V seals located in the upper and lower seal plates, combined O-ring between the rudder bearing and rudder stock ensure the bearing is watertight.
  •  Bearings are available in any size from 60mm upwards.                                   To date the largest bearing  we produced is 1150mm ID!! ( Maltese Falcon supply).
  •  A full range of complementary parts is available for the Type 4 bearing, some of which are necessary for a new installation ( see below)
  •  All parts are precision-machined in-house at JP3 to ensure quality and all aluminium parts are anodised in our in-house anodisation plant to ensure quality and prevent corrosive action.

Our type 4 bearings are Germanischer Lloyd and Lloyd Register Type Approved.

Type 4 bearings are available in an extensive range of styles to suit every mounting arrangement and loads. If there is not a standard design a special bearing can easily be designed.


The 3 main styles of type 4  bearings are outlined below but there are many more.

As a guide to the complete range, download the below document to obtain all Type 4 Bearings designations.



Type 4 description 2014.pdf
Adobe Acrobat Document 139.8 KB



The type 40 to 45 bearings are the ‘original’ range of bearing range of spherical roller bearings produced by JP3.

All the ‘original series’ features bearings with 1, 2 or 3 rows of rollers.


The single and 3 roller bearings are available for both new and existing projects.

Bearings are available with either Ertalyte® or Peek® Rollers.


The 2 roller bearings have now been superseded by the type 48/49 racing series. For all new projects the type 48 series is the preferred bearing where a 2 roller bearing is required.


Type 48/49 - ‘RACING SERIES’



The Type 48 design is based on our proven Type 40 ‘Original Series’ design.

The first bearing was created for the 2003 Louis Vuitton and Americas Cup; the design of this new bearing was pushed to its limits with every effort made to reduce weight. This resulted in a 250mm diameter two roller bearing that weighed only 4.1 kilograms.


This bearing proved its efficiency and reliability during the 2003 Louis Vuitton and Americas Cup and where used by over half the race fleet.


Having proven the bearing on the racetrack JP3 has further developed bearing, with greater watertightness and safe working loads to provide the security level demanded of yachts competing in transoceanic races.


This range can offer significant weight savings and in some cases a type 48 bearing is less than half the weight of its type 40 series equivalent.

The type 48 racing series use Ertalyte® Rollers, while the type 49 series are fitted Peek® Rollers for increase working load.

Both series are available in either internal or external Mounting Styles.



The Type 47 design is a further development of the Type 48/49 Racing Series. With the type 48/49 series the roller material is changed from Ertalyte® to Peek® to increase the bearing working loads.


With the type 47 series the bearing uses the Peek® roller material and has a similar working load as the same sized type 48 bearing. The use of the Peek® allows for smaller a roller which reduces the overall bearing size further reducing the bearing weight.







Whether the rudder structure is welded or laminated into the hull JP3 supply correct housing solution to ensure the correct positioning and fixing to the hull. With bearings with tapered housings these parts ensure the correct installation of the bearing.


Composite housings are made from an E-Glass laminate, so for installation into a carbon hull this ensures the correct electrical isolation and long term reliability of the bearing.


Metal housings designed to be welded into the hull structure are machined from solid marine grade aluminium. Other metals are available on request.


Flanged housings available on request.



Specifically designed to carry heavy axial loads, retaining rings secure the rudder in position.

These rings are clamp onto the rudderstock and locate against the moving inner race. There will be one ring above the lower bearing to support the rudder and a second ring below the upper bearing, to account for any rudder buoyancy and upwards grounding loads.


With bearings with tapered housings these parts ensure the correct installation of the bearing.



Where axial loads are high due to a heavy rudder,  additional thrust races can be fitted above the lower bearing to ensure the axial loads can be carried satisfactorily.






JP3 inner sleeves are designed to fit with the inner races of your bearings. They are female moulded composite part with a hard tooling grade gel coat external finish. Inner sleeves are a fast cost effective way a composite rudder stock round.


exemples de montage cd composite.pdf
Adobe Acrobat Document 89.6 KB
typeIV top bearing layout composite hull
Adobe Acrobat Document 107.8 KB
typeIV bottom bearing layout composite
Adobe Acrobat Document 144.7 KB
Alu boat housing example.pdf
Adobe Acrobat Document 95.9 KB


JP3 Type 4 Installation Composite V6.pdf
Adobe Acrobat Document 3.3 MB
JP3 Type 4 Installation Metal V2.pdf
Adobe Acrobat Document 1.1 MB


JP3 Type 4 Servicing V1.pdf
Adobe Acrobat Document 299.1 KB

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