The canting keel system

The canting keel is a lever attached to the keel/hull intersection on a yacht. On one side of the lever is the daggerboard with the bulb, and on the other a force is exerted. Initial models moved the swinging daggerboard mechanically, but current designs employ hydraulics for that purpose. A leak causing a loss in pressure to one of the hydraulic rams which controls the canting keel on Central Lechera Asturiana has been the cause of a technical stop for the team.

Canting keels became competitive when hydraulics came into use to power them. Thanks to hydraulics there are now systems which can fully displace the keel (40º to either side) in just 20/30 seconds. What used to be moved using winches and gears is now in the hands of the same technology which can raise buildings and move power diggers...

A keel on an IMOCA Open 60 consists of a sturdy fin with a bulb weighing some four tonnes attached to the tip. The blade is fitted with a pivot point at 7/8 of its length, supported at the bottom of the hull. The system is operated merely by moving the inside of the fin to one side using a simple hydraulic piston. This force on the outside is the source of the displacement of the bulb to the opposite side.

The hydraulic piston

The hydraulic piston system in a canting keel works similarly to the brakes on a motor vehicle. When the switch is activated (the brake pedal on a car) a pump pushes oil into the system. The pumped oil displaces the piston bearings, which then moves the keel with a rod. As the oil is injected, the rod is pushed deep into the canting keel and the bulb moves in the other direction.

One of the most important features of a canting keel is the need to be watertight. As with vehicle brakes, any loss of fluid due to damage to a part or at any join, impedes its correct functioning. In this case it becomes essential to replace the defective part and to refill the system with oil.

Diagram to show workings of a canting keel. © Cristina Barredo / FNOB