Hydraulic Steering Conversion
The old mechanical steering system that had been around since the boat was built for all we know had some problems that limited its functionality in a very irritating way. The Winga 87 has two steering positions; a tiller arm mounted on the rudder axis in the aft and a steering wheel mid ship. The steering wheel was connected to the rudder by a wire running from a gear box behind the panel the steering wheel is mounted on (left picture view from the starboard cabin under the pilot house). The wire was connected to an arm attached to the rudder tiller arm (right picture underneath the starboard bunk in the aft cabin).
The system allowed the steering wheel to be disconnected with a lever. The tiller in the aft was however always engaged as it is connected directly to the rudder axis. The problem was that the wire system didn't allow the rudder to turn fully. The 3,5 cm gap in the picture below shows the difference between the maximum possible angle of the rudder axis and the end position of the arm connected to the steering wheel. On the picture, the steering wheel is turned to starboard as much as possible. When the steering wheel was engaged the boat lost a substantial amount of maneuvering capability. With the steering wheel disconnected, the rudder axis could be turned all the way to close the gap completely.
Even though the problem likely could be solved without replacing the entire system, we felt that with something as important as maneuvering it would be worth the effort to install a new effective and reliable hydraulic system instead.
The hydraulic system consists of a pump that replaces the gearbox behind the steering wheel and a cylinder that replaces the arm attached to the rudder axis. Hoses filled with hydraulic fluid transfers force from the steering wheel pump to the cylinder and the rudder. We choose a set up made by Norwegian manufacturer Sleipner.
The appropriate size of pump and cylinder is determined by among other things the length and top speed of the boat and the area of the rudder fin. To find out whether the new system would improve maneuverability I had to find out how much the hydraulic cylinder arm would extend going from one end position to the other and compare that with the old mechanical arm. The arm of the hydraulic cylinder had to be able to extend further than the old system but not beyond the maximum angle that the rudder axis was able to turn.
After finding the appropriate components the installation process could begin. First I removed the old mechanical steering wheel gear box. The hole had to be widened in order for the pump to fit.
Picture of some of the components of the old system below.
The hydraulic cylinder is attached to a ball joint which allows it to move a bit as it extends. This ball joint had a mounting plate with four holes that needed to fit the four holes in the mounting plate attached to the of the boat. Unfortunately, the holes in the cylinder ball joint did not match the holes in the mounting plate where the arm from the old system was attached so we had to drill three new. Was done easily with a metall drill bit and and a power drill.
When installing the steering wheel pump, it was a bit tricky to find room for some of the switches in the electrical panel as the pump is substantially larger than the old gear box. We had to replace some switches with new moderns ones that took up less space behind the panel.
Next thing in line was to find room to run the hydraulic fluid hoses from the pump to the cylinder and back again. We used a total of 10 meters of hose, 5 meter in each direction.
In the first picture in the slideshow below, you can actually look straight into the starboard aft cabin through the open hatch. The most obvious thing would be to run the hoses through the bulkhead below the hatch. Unfortunately, one of the two fresh water tanks is tightly fitted there so the hoses had to take a detour towards the middle of the boat into the storage space behind the engine and then down and towards starboard into the space below the aft bunk.
When connecting the hoses it was important to take a moment to make sure the hoses are attached to the right ports in the pump and in the cylinder. If not, the rudder would turn the boat in the opposition direction the wheel is turned. Our pump has two ports placed horizontally on the backside. If I remember correctly, turning the wheel for instance to the right would increase pressure in the hose attached to the right port (looking towards the bow), need to double check this though. Connecting that hose to the port in the cylinder closes to the cylinder arm would cause the boat to turn starboard.
After both hoses had been firmly connected to both pump and cylinder it was time to fill up with hydraulic fluid. In a previous picture the filling hole in the pump is visible (covered by a white cap). To fill the system you fill oil while simultaneously turning the wheel thus pumping the fluid towards the cylinder. The most time consuming part of this process is to get rid of the air bubbles. In a previous picture showing the cylinder, you can see two yellow caps and two red caps. The yellow caps is where the main hoses go. The red caps are for air bleeding. To air bleed the system, you connect a preferably smaller transparent hose. The other end of that hose goes into a empty and clean container (so you can reuse the fluid). For instance; continuously turning the wheel to starboard while pouring fluid into the pump will push that fluid though the corresponding hose towards the cylinder. The fluid will go through the cylinder and back towards the pump through the other hose. Once back in the pump again air bubbles will exit through the filling hole in the pump before it is pump back towards the cylinder again together with new fluid that are being poured into the system. Getting rid of the air bubbles was a process of filling the system with fluid and then cycle that fluid until the air has escaped through the pump filling hole. To check progress, you open the air bleeding valve on the cylinder (where the small transparent hose is attached) and look how much bubbles are left. This was quite time consuming but eventually we got rid of the air, closed the filling hole and the steering wheel turned the rudder nice and smoothly in the direction you would expect it to!
