The Hook-series mainsail head cars, through an inside mechanism, are able to engage a specific locking insert inside the track and hence to block the mainsail head releasing the halyard from the load.
Advantages of the Hook cars
The possibility to free the halyard from the tension produced by the sail offers many advantages:
- the load applied on the mast is halved, therefore the compressions on mast step, standing rigging and hull beems are reduced with a consequential reduction of the stresses on boat and mast (which leads to a lighter mast)
- maximum working loads are higher than those of any commercial clutch
- the wear of the halyard at the clutch is reduced(since the tension of the halyard acting on the clamps is given just by the mainsail weight)
About working loads, we could just remember that the Hook system was born some few years ago for oceanic trimarans because the tensions caused by the huge square-top mainsails were so high that the use of any kind of clutch turned out to be pointless and therefore skippers had to keep the main halyard on winch constantly. The old Hook Maxi (which was installed on Giovanni Soldini's "Tim - Progetto Italia" trimaran, among others) had a maximum working load of 10,000 kg and could easily keep the mainsail hoisted and set the winch free.
How it works
The working principle of the Hook car relies on two small lines, as shown in picture.
The red line releases the hook, which is pulled toward the track by a spring. When the car reaches a locking point on the track (at the mast head or at reefs height), the hook inserts inside the track and prevents the mainsail head from falling.
The green line, on the other hand, pulls back the hook inside the car, which allows the mainsail to drop. To lower the sail, you just have to haul in the halyard a little to free the car and then you can pull the green line until the hook is fully inside (then it automatically locks on "open" position).*
* colours of the lines are intended just for graphical purpose
New Hook cars, sizes 22 and 24
The Hook car 22.160R takes the place of the old 22.100. The new feature is the fixing point of the lashing on the car, which is stronger and allows the mainsail head to be more mobile. As proof of interest and trust in this system, the Hook 22 has been chosen by Nautor for the ClubSwan 50 class.
Is now in development the new Hook 24, similar to the 22 but designed to work with the 24 mm track and with higher loads.
