The Columbia 40 uses a hydraulically controlled centerboard system. Gravity lowers the board and the hydraulic system raises it. There are three cylinders in series that act on a system of pulleys, a metal rod, and a pendant to raise the board. The crew uses a pump in the starboard cockpit locker to pump hydraulic fluid into the cylinders. The fluid comes in on the shaft end of each cylinder causing the piston to draw the rod INTO the cylinder.
The cylinders draw a pulley aft, which in turn pulls the cable around another pulley. The cable pulls a metal rod through a packing in the hull. There is a pendant that runs from the other end of the rod to the centerboard.
Here is a rough sketch of a C-40 Centerboard System.
The following three pictures are oriented such that the top of the picture is aft.
This picture shows the three hydraulic cylinders. The round object to the right is the sender for the centerboard position indicator.
This picture shows how the forward cylinder rod attaches to the pulley and the cable.
At the bottom of this picture you can see the metal rod entering the stuffing box.
The big, square fiberglass lump is evidence that someone has worked on this system.
