Jefa GRP rudder blades



Jefa Marine produces a wide range of standard rudder blades for boats from 22 to 60 feet length. This unique product line offers the boat builder a modern rudder blade without investing in expensive molds. The rudders are made in our modern GRP factory and are available in nine sizes depending on the boat size.

What makes the Jefa rudder blades unique and distinct from all other rudder blade producers and yard made rudder blades is the production in solid aluminium molds (see the pictures at the right). This unique production method allows very high pressures to be used in the gluing and foaming process. Traditional glass fiber molds don't allow any pressure from inside the blade, so one can't be sure of a good bonding of both sides.
Another unique feature is the overlapping parts of the blades. This feature substantially strengthens the blade integrity making it nearly impossible to split. Traditionally the rudder halves are glued heads on together, allowing only a very small contact area which causes the blade to split easily. 
The cross section shown in the picture at the right side perfectly shows all advantages of our unique production method. Due to the high pressure foam filling system, the foam is guaranteed present in all remote ends of the blade so no air pockets can be present. Also well visible is the large overlap at the front and the huge glue contact area at the aft side of the rudder blade.
The left illustration shows the way the Jefa rudder blades are build. The blades are made of one layer of 300g chopped E-glass and 3 layers of 600g. The metal (Aluminium or Stainless Steel - for details see this web page) rudder stock is MIG welded to the spokes which are glued to the rudder blade at each side. On top of that there is extra lamination at one side of 2 layers 600g glass. This extra laminate is very important as any movement between the rudder stock and rudder blade is fatal for the lifetime of the rudder. All rudder blades comply to the ISO 12215-8 norm. Please look further on the page for more detailed information on sizes, production methods and specials. All Jefa rudders are delivered in a gel coat finish and should be treated with non-water penetrable epoxy coating and anti-fouled. This will prevent water entering in the gel coat and underlying GRP structure. For detailed instructions, please open this PDF instruction leaflet.

Video showing the rudder blade production:
 

RACING blades:
When the budget is not there, but a thin profile like a carbon rudder profile is required, the JEFA racing blades are the best alternative! The profile is as thin as carbon solutions at only a fraction of the costs. In IMS ratings these rudders work great as they are as thin as carbon, but don't get the heavy rating. These rudder blades are only available with high strength stainless steel rudder stocks (AISI630 or 16PH). Please read more on this material on our materials page. By adding a wax or solid insert in the mold, the top and bottom shape can be altered easily. Please follow this link for all 2D and 3D CAD data on our rudder blades. Rudder stocks are made to suit customer requirements and are unique for each rudder we make.

CRUISING blades:
The JEFA cruising blades are the perfect solution for modern cruising-racing production boats. The modern blade shape is thick enough to allow aluminium AL6082 rudder stocks which are normally used by production yards. Please read more on this material on our materials page. By adding a wax or solid insert in the mold, the top and bottom shape can be altered easily. Please follow this link for all 2D and 3D CAD data on our rudder blades. Rudder stocks are made to suit customer requirements and are unique for each rudder we make.

  Jefa racing rudder blade prices: (retail prices excl. VAT and excluding rudder stock)
The price of the rudder stock is variable due to the custom length, material and diameter. Please tell us the length waterline and displacement, so we can calculate the rudder stock diameter for you.
RUD31R GRP rudder blade 0.482 m 1.172
RUD33R GRP rudder blade 0.610 m 1.324
RUD35R GRP rudder blade 0.753 m 1.475
RUD45R GRP rudder blade 1.029 m 1.631
RUD48R GRP rudder blade 1.137 m 1.706
  Jefa cruising rudder blade prices: (retail prices excl. VAT and excluding rudder stock)
The price of the rudder stock is variable due to the custom length, material and diameter. Please tell us the length waterline and displacement, so we can calculate the rudder stock diameter for you.
RUD26 GRP rudder blade 0.495 m 1.074
RUD30 GRP rudder blade 0.545 m 1.182
RUD34 GRP rudder blade 0.711 m 1.335
RUD40 GRP rudder blade 0.900 m 1.486
RUD46 GRP rudder blade 1.111 m 1.649
RUD55 GRP rudder blade 1.448 m 1.909
RUD-MOD Modification to rudder mould 370
Jefa rudder blades are delivered in a white gel coat finish and for future protection should be treated with non-water penetrable epoxy coating and anti-fouling. Failing to do so invalids the warranty. Read this manual for more info.

RUD26 rudder blade dimensions:

RUD30 rudder blade dimensions:

RUD34 rudder blade dimensions:


RUD40 rudder blade dimensions:

RUD46 rudder blade dimensions:

RUD55 rudder blade dimensions:

RUD31R rudder blade dimensions:

RUD33R rudder blade dimensions:

RUD35R rudder blade dimensions:

The manufacturing process of the rudder blades:
Jefa rudder blades are very stiff, strong and durable as they are made in a solid aluminium mold and foam filled under pressure. The production process will be explained in the below sequence.
 
All rudder molds are produced out of a solid piece of aluminium in our machine shop. Custom molds can be made to suit a specific rudder blade design.
 
All molds are high gloss polished to achieve the best possible blade surface.
 
The mold is carefully cleaned and the edges are taped and covered in plastic.
 
Both mold halves are polished with mold release wax.
 
The molds are hand painted two times with gel coat, with a hour interval.
 
Sharp corners on top and bottom are filled with polyester glue, radius 10-12mm.
 
One layer of 300g powder bonded mat, with vinylester resin is added.
4 layers of 600g emulsion bonded mat, with polyester resin.
The mold is cut clean, the extra laminate at the top and front is for a better connection between the two blade halves.
The rudder stock is carefully positioned in the mold.
The rudder stock is carefully positioned in the mold.
Polyester glue is added on all contact places.
The rudder stock is carefully glued to the blade.
2 layers of 600g is added on each spoke for extra connection.
The edges are glued with polyester glue.
The spokes are glued to both blades and laminated to one side.
The form is filled with PU foam. This foam will dramatically expand in size and completely fill up any free space in the blade. Within 90 seconds the molds have to be closed, otherwise this set is a loss.
Just before closing.
Finally both parts meet and are secured as the pressure runs up high due to the expansion of the foam.
A vent hole in the mold assures any air is pushed out so the foam is completely spread in the blade.
After a few hours rest, the mold parts are separated and the blade edges can be finished by hand.
 
The shaft entrance in the blade is sealed with Sicaflex 221
The finished rudder.
A destructive test clearly shows the overlap and foam filling.
The unique production process in metal molds and high pressure foam guarantees a complete filling of the blade.
The cut of the bottom of the blade. The large overlaps are clearly visible and will ensure the blade parts will never separate.
Rudders not transported by ourselves are individually packet in carton boxes and grouped on pallets.
For shipping large quantities of rudders to yards, a special pallet that can take up to 20 rudders has been developed.

Modifications to the standard rudders:
Via inserts in the mold, it's possible to modify the rudder blade shape. Inserts can be made for the bottom and the top of the blade.
 
RUD30 rudder blade with a modification in the bottom and in the top.
 
The complete finished RUD30 blade with modifications.
 
Detail of the modified bottom of the blade.
 
RUD30 rudder blade with a modification in the top for a production boat builder.
 
The aluminium insert in the RUD30 mold.
 
The ready rudder blade RUD30 with special top.
 
Detail of the special top side.

Jefa rudder blade CAD data:
Using below link, you will transferred to our document server ftp.jefa.com where you can find 2D AutoCAD drawings and 3D IGES files of our rudder blades. Please don't hesitate to contact the Jefa commercial team for any specific inquiries.
Rudder blades CAD library.
(when you can't open our ftp server, your browser doesn't support anonymous ftp access (mostly due to a proxy server), please contact us so we can mail you the library).