GC Marine
homeservicescarbon fiberstanding riggingcordageshowcaseabout usfor sale

(back to showcase home page)

Lending Club - Modified ORMA 60 - Adapt Daggerboard Bearings built by Artemis America's Cup Team to work with old Boards

Lending Club used to be an ORMA 60, ex Bonduelle, ex Gitana 12. Artemis Team used the trimaran to test their AC 72 wing sail.They lengthened the boat to 72' and in the process they built new daggerboards and bearings for the boat. When the boat sold, the bearings needed to be adapted to work with the old dagger boards.


The bearings are cyllindrical because the boards are "L" shaped, so they have to rotate as the boards are raised and lowered. The liners you see are machined from ertalyte, a special plastic. They are laminated to a carbon cyllinder.



Since the inside shape of the bearings didn't match the outside profile of the boards delivered with the boat, the first order of business was to remove the liners on the inside of the bearings. We sanded the old spabond adhesive down to the carbon layer.

The existing boards had a smaller profile which fit inside the bearings, but not correctly. So we needed to add material to the old bearing profile as well as modify the shape to fit the boards. Our target was .5mm of play between the boards and the liners in either direction athwortships.

We worked with animators from Lucas Films who have experience turning scans into 3-d objects. We gave them the daggerboards which they scanned. The resultant board profile was super-imposed digitally to the profile of the bearings which we had in CAD drawings. Based on the data we knew exactly how to align the upper and lower bearings (port and starboard) and how the existing board profiles could fit, and what the space in between the ertalyte liners and the carbon strucure would look like.
     

The animators gave us drawings for aluminum templates based on the inside shape of the bearings. Each template had two bolt holes used for locating a foam plug shaped to the existing boards + the thickness of the ertalyte liners.

The bearings with the aluminum templates and bolt holes.


We received new ertalyte liners but they were flat, and had to be heated to a certain temperature while clamped in a jig to adopt the profile of the boards.


By injecting Spadond adhesive between foam plugs shaped like the boards and the carbon wall of the bearings, we now have the new inner profiles. Once the plastic liners are glued on, the profile will match perfectly that of the boards.
       


We used thin wire to make sure the ertalyte liners had an even spacing so the spabond wouldn't get squeezed out completely during the gluing process.

Time to dry-fit and see how close we are. We need some room for the Spabond between the liners and the new inner profile.

As evident here, the tolerances are tiny. Any irregularity of shape and the board will not slide through the liners or will slide through, but will load up unevenly. The static loads expected are several tons.


To get the exact .5mm of play we seeked, we taped the ertalite liners untill all the tape layers plus the thickness of the vacuum bag equalled .5mm on either side of the board. Then we forced the bearings and the liners with fresh spabond onto the boards. Once the bag and the tape layers removed, we should have exactly .5mm of play in either direction.

   

We had one board to work with and used it to glue all the liners to all the bearings, port and stbd, top and bottom.

The vacuum bag really served to keep all the glue in place and not get completely forced out from under the liners.


The liners are glued in. Now we want to add biaxial carbon to the liner edges to hold it in place .


A finished bearing, with the liner edges laminated perfectly.

A finished bearing, close up.