Emptying Boat Hydraulic Steering: Twin Engine Guide

Hydraulic steering systems are a popular choice for boats as they are low-maintenance, safe, and provide light and nimble controls. They are also highly responsive, making them ideal for high-speed boats and high-torque engines. However, issues can arise, such as unresponsive steering or leaks, which can be caused by air in the hydraulic system or the need for a hydraulic fluid change. To fix this, the system must be bled to remove the old fluid and any air bubbles. This process requires two people and involves filling the system with new hydraulic fluid and bleeding it of air through the starboard and portside bleeder valves. It is also important to check for any leaks before adding new fluid, as this could reintroduce air into the system.

Bleeding the hydraulic steering system

First, get some oil-absorbent pads ready in case any hydraulic fluid leaks. Open the reservoir at the helm and top it off. Then, connect the filler tube and oil bottle, and invert the oil bottle so the filler tube fills with hydraulic steering fluid. Poke a hole in the bottom of the inverted bottle so the fluid can freely run out of the bottle and into the system. The person at the helm needs to keep an eye on the filler tube and replace the bottle if it runs empty to prevent introducing more air into the system.

Next, turn the wheel all the way to starboard. Then, the person positioned at the cylinder should open the starboard-side bleeder valve and prepare a container to catch the fluid that comes out. It’s a good idea to attach a short length of hose to the bleeder valve to minimise the mess. The person at the helm should then turn the wheel to port, until air bubbles cease coming out of the bleeder valve. When no more air is coming through, the valve can be closed. Now, repeat the process with the portside bleeder valve.

If your boat has two stations, you’ll need to do each one individually. Simply follow this same procedure at wheel number one, then do it again from wheel number two.

To check if the system is fully purged, you should be able to turn the wheel smoothly from lock to lock without bumps or hesitations. A sea trial is the best way to get a feel for how smoothly the steering system is working, but at the dock, you can usually feel if there are any major air bubbles remaining.

Adding hydraulic fluid

Step 1: Gather the Necessary Materials

Before you begin, make sure you have the right hydraulic fluid for your boat. It's recommended to use hydraulic steering fluid that meets Mil-Spec H-5606C standards, such as Sea Star/Bay Star No. HA 5430. Additionally, you'll need an adapter hose, like Sea Star No. HA 5438, and a pushpin or similar tool. A rag will also come in handy to wipe up any spills or messes.

Step 2: Prepare the Filler Tube and Fluid Bottle

Start by threading the filler tube into the helm pump. This will create a secure connection between the helm pump and the fluid bottle. Once the filler tube is in place, take your bottle of hydraulic fluid and thread it onto the filler tube. This will ensure that the fluid can be dispensed directly into the system.

Step 3: Puncture the Fluid Bottle

To allow the fluid to flow out of the bottle and into the system, you'll need to create an opening. You can do this by puncturing the bottom of the bottle with the pushpin. Alternatively, you can cut the bottom off the bottle and create a funnel-like shape. This will allow the fluid to flow more easily.

Step 4: Invert the Fluid Bottle

Once the bottle is prepared, turn it upside down, similar to an IV setup. This will allow gravity to assist in dispensing the fluid into the system. It's important to ensure that there is always fluid in the filler tube. If the fluid drains out, you may be pumping air into the system, and you'll need to start over.

Step 5: Operate the Steering Wheel

Now, turn the steering wheel hard to starboard. This will put the system in the optimal position for bleeding the air and ensuring a smooth flow of hydraulic fluid.

Step 6: Open the Starboard Bleeder Nipple

Located on the steering cylinder, you'll find the starboard bleeder nipple. Open this valve to release any air or fluid that needs to be purged from the system. You may want to have a container ready to catch any fluid that comes out. Additionally, attaching a short hose to the bleeder valve can help minimise messes.

Step 7: Turn the Steering Wheel to Port

With the starboard-side bleeder valve open, turn the steering wheel to the port side. This action will pump air and fluid out of the bleeder fitting. Continue turning the wheel until you see an air-free stream of fluid. It's important to ensure that all air is removed from the system.

Step 8: Close the Starboard Bleeder Nipple

Once you've achieved an air-free stream, close the starboard bleeder nipple. This will seal the system and prevent further fluid or air from escaping.

Step 9: Repeat for the Port Side

Now, you'll repeat the process for the port side. Turn the steering wheel hard to port and open the port bleeder nipple. Turn the steering wheel to starboard, pumping air and fluid out of the bleeder fitting. Again, watch for an air-free stream, then close the port bleeder nipple once it's achieved.

Tips and Additional Information:

• It's recommended to puncture the bottle on the bottom side, not the very bottom. This allows you to place the pushpin back in and store a partially full bottle without leaks.
• Remember to check your boat's steering system annually or every 200 hours of operation. This includes inspecting seals, hydraulic oil condition, and checking for leaks.
• While Sea Star hydraulic fluid is widely used, alternatives such as aircraft hydraulic fluid or mixtures of automatic transmission fluid (ATF) and diesel have been suggested by some boat owners. However, it's important to exercise caution and refer to your boat's specific recommendations.

Troubleshooting unresponsive steering

Firstly, check for any leaks in the hydraulic system. Leaks are a common cause of unresponsive steering, as air can enter the system and cause the steering to feel soft or mushy. If you find any leaks, fix them and bleed the system to remove any air. This is done by opening the bleed valve and allowing the air to escape while turning the steering wheel.

If there are no leaks, the problem could be related to the hydraulic fluid. Check the fluid level and top it off if necessary. Also, inspect the fluid by dipping a screwdriver or pen into the reservoir. If the fluid is discoloured or has a bad odour, it needs to be changed. Bleeding the system will remove the old fluid and any air that may be present.

Another possible cause of unresponsive steering is a stuck relief valve in the hydraulic helm pump. To fix this, turn the wheel to the hard full lock in one direction and then the other, applying pressure until the relief valve opens.

If the steering is slow or won't turn all the way, it could indicate an issue with the steering cylinder seals. Check the seals for any signs of fluid escaping and replace them if necessary. Also, inspect the cylinder shaft, and the inside of the cylinder for any corrosion or damage, and clean or replace them if needed.

Finally, if your boat has power-assisted steering, ensure that the steering pump is functioning correctly and attached to the engine or electrically driven. If the steering was recently purchased, it may be inherently hard to turn, and not actually unresponsive.

Steering wheel size

The steering wheel is a critical component of a boat's hydraulic steering system. When upgrading to a hydraulic steering system, it is essential to ensure that the steering wheel's mounting location does not interfere with other equipment such as throttle and shift levers. The American Boat and Yacht Council (ABYC) recommends a minimum clearance of 2.5 inches between the outer diameter of the steering wheel and these control levers. This clearance ensures unrestricted movement and manipulation of the steering wheel.

The size of the steering wheel is an important consideration. Smaller diameter steering wheels require more turns to achieve the same rudder movement as larger wheels. This is because larger wheels provide greater leverage, reducing the required steering effort or "rim force". For example, a 1.5-inch bore ram with a 7-inch stroke and a typical helm pump with a 2 cubic inch per revolution output would require approximately 5.5 turns to achieve full rudder travel. However, with a larger diameter wheel, you can achieve the same result with less effort.

When selecting a steering wheel, it is also important to consider the number of turns lock-to-lock desired. A higher number of turns lock-to-lock typically results in lower steering effort, while a smaller number of turns may be preferred for quick manoeuvring. The number of turns is influenced by the displacement of the ram and the helm pump. A larger displacement ram will require more turns but will help keep the system pressure low, which is important for comfortable steering.

In addition to size, the placement of the steering wheel can also impact the steering experience. A traditional steering wheel arrangement with a larger diameter (24-30 inches) may be more challenging to operate when the number of turns lock-to-lock exceeds 3-4. On the other hand, a smaller diameter wheel (7-9 inches) with a "brodie knob" installed in a bus-like flat or tilted position can make 6-10 turns lock-to-lock feel more manageable.

In summary, when selecting a steering wheel for a boat's hydraulic steering system, it is important to consider the wheel's size and placement. A larger diameter wheel provides greater leverage and reduces steering effort, while smaller wheels may require more turns to achieve the same rudder movement. The number of turns lock-to-lock and the system pressure are also influenced by the steering wheel's size and the displacement of the ram and helm pump.

Checking for leaks

Start by inspecting the hydraulic fluid level at the helm filler plug. If the fluid level is low, top it up using the approved hydraulic fluid. If you have recently topped it up and the level is still low, there is likely a leak in the system. Even a tiny pinhole-sized leak can cause a rapid escape of fluid due to the high pressure in the system.

Next, carefully examine the hoses and connections for any signs of damage or wear. Look for cracked, perished, or broken hoses, as well as loose hose end fittings. These are common sources of leaks. If you notice any issues with the hoses, they may need to be replaced.

After addressing the hoses, turn your attention to the cylinder. Wipe the area underneath the cylinder and the bottom of the helm pump with a clean, white paper towel to check for any traces of hydraulic fluid. If you find fluid, the cylinder is likely the source of the leak. In this case, you may need to replace the cylinder or its seals.

Additionally, pay close attention to the end caps and glands of the cylinder housing. Clean them and then turn the engine to port and starboard several times to check for any reappearance of fluids. Visual inspection can often reveal the exact source of the leak. If the end caps are the issue, verify the condition of the main stainless steel rod; if it is worn or pitted, replacing the end caps may not solve the problem.

Finally, if you are unsure or uncomfortable with performing the inspection or repairs, it is best to consult a certified marine technician. They can help troubleshoot and service the cylinder according to the manufacturer's specifications. Remember, it is crucial to address any leaks promptly to ensure the safe and reliable operation of your boat's hydraulic steering system.

Frequently asked questions