marine hydraulic system

Certainly you cannot own a boat and not have heard about “hydraulics” or the vessel’s “hydraulic system,” or systems. But what exactly are “hydraulics” and why are they so important to the operation of your yacht?

In a nutshell the mechanical engineering behind any hydraulic system, is a force applied at one point is transmitted to another point, using a fluid. The “force” is almost always amplified during the process. Just as an electrical system transmits “electrical energy” through wires, a “hydraulic system” transmits hydraulic energy via this fluid, through a series of tubes. The fluid is usually some kind of specialized oil, or “hydraulic fluid.”

The fluid is “incompressible,” which means it retains the power of the force applied to it. Think of two pistons in two oil filled cylinders, with an oil filled pipe between them. If you push down on the first piston, you will force the oil down, through the pipe, and it will drive up the second piston. This is a basic hydraulic pressure machine.

diagram of hydraulic system

The principal can be applied to any number of systems on cars, aircraft, and of course, luxury motor yachts.

Marine Hydraulics 101

While modern marine hydraulic systems can be very complex, any hydraulic system is basically made up of the same four parts:

  • A hydraulic pump that converts mechanical energy (applied force) into hydraulic energy.
  • A series of valves that can direct the flow of the hydraulic energy.
  • Hydraulic cylinders that convert the hydraulic energy into linear force (up and down-like) motion, or hydraulic motors that convert the hydraulic energy into rotary-like motion
  • Equipment that completes the system such as: heat exchangers, filters, tanks, and pipes, etc.

Hydraulic systems on boats are used in countless applications from steering and main propulsions systems, to “get home drives,” generators, windlasses and tender lifts.

In many ways, it is thanks to hydraulics that motor yachts have become safer, more comfortable, and easier to operate.

example of boat hrdraulics

Marine Hydraulics Maintenance and Repairs

OK, so now that you have a basic understanding of what hydraulics are, you probably think the biggest problem with a liquid driven system is leaks. Good thought! But, actually you would be wrong. Leaks are common in hydraulic systems, and they are not necessarily the biggest cause of system malfunction or breakdown.

In fact, the biggest issue faced by marine hydraulic systems is contamination. When hydraulic fluid gets contaminated, foreign matter literally “gums up the works,” and can cause all sorts of problems. Hydraulic fluid can get contaminated during the initial installation of the system, or more likely due to unskilled technicians doing routine hydraulic system maintenance, such as filter changes.

That is one of the main advantages to hydraulic systems, and what makes them so attractive for marine applications. Other than keeping the fluid cool and clean, hydraulic systems do not require that much maintenance. Hydraulic fluid is not like the oil in your car; it does not have to be replaced regularly. It is more like your car’s brake fluid, which may just need to be topped off occasionally. In fact, your car’s brakes are an excellent example of a hydraulic system.

typical marine hydraulic system

However, those parts of your boat’s hydraulic system that are responsible for keeping the fluid cool, clean, and flowing, such as the hydraulic pumps and heat exchangers, must be monitored regularly for any signs of wear, as do all the seals and filters.


Operating a motor yacht can be costly. You can reduce your expenses, and avoid costly repairs by keeping her well maintained. On Demand yachting from FYM can help. If you would like to learn more, or if you have any questions or comments about this blog post, do not hesitate to contact our Yacht Management specialists, or call us at (954) 900-9968.