Get yourself connected
Is your mast join ferrule a weak point - and does it affect the bend curve for your sails?
The top and bottom parts of a two-piece windsurfing mast are connected with a joint called a ferrule.
Duck - He's turning round!
This connection element is essential because, these days, everyone likes to have easily transprotable masts.
(In the old days, all masts were produced as one piece, so hauling your gear through airports was hilarious as you knocked everyone over each time you turned around!)
Looking to the construction details of this connection joint, it must be strong to cope with the high bending forces rig tension brings.
But, if made too long - and too stiff - the bend curve of the mast will be affected.
Also the amount of play between the joint and the top of the mast is critical.
Too much and the mast has a pronounced kick, or too small and disconnection will require at least four of your friends.
Normal production methods cut the mast in half and involve gluing a ferrule into the bottom part of the mast afterwards.
This has two disadvantages. Positioning the glued ferrule in the middle of the bottom part could lead to negative long-term effects caused by point loading (the mast is conical in shape so contact is not even).
Hence, as a result, there could be a severe kink at the connection point.
On top of that, the extra wall thickness in the bottom part results in a discontinuity in the bend curve.
Unifiber has adopted a technique enabling an integrated joint during production of the bottom part of the mast.
During production of the bottom part of the mast the ferrule is constructed at the same time.
This requires a mandrel that is extra tapered at the end.
At Unifiber we wrap layers of prepreg (pre-impregnated with resin for maximum consistency of wet-through and lightest weight) material around the mandrel.
As the material can be tapered without having to cut it, there are no weaknesses around the ferule.
To enable a perfect fit of the top of the mast into the ferrule, a diamond type of grinding machine is used.
As a reference the internal dimension of the mast top is taken.
This technique is not only homogeneous, more reliable and stronger, but also causes minimum influence on the bend curve of the mast.