Archive | Hydraulics

Bow and Stern Thruster Maintenance

Bow and stern thrusters are critical components on any mega yacht. Not only do they increase the maneuverability of large vessels but also play an important part in the safety of other boats around the docks particularly in larger vessels is tight spaces. Most of these systems are driven by hydraulics on vessel from 80-180 feet but others are driven by electric motors.

When hauled it is a good idea to drain the gear oil out of the leg to check for water or metal.  If no water is present, add fresh gear oil and the service is done.  New seals can easily be added depending on the brand and model of thruster.  If salt water is present, the gear leg can be removed for disassembly and assessment on gears and bearings.  More often, we find oil in the tunnel beneath the propeller a few days after haul-out that indicates leaking shaft seals that would need to be replaced. While we typically do not change out zincs unless requested, zincs for bow and stern thrusters are specific to the brand of thrusters so that would be included in the maintenance service.  

We were recently called on to service a bow thruster on one of our repeat clients where the propellers complete broke apart due to improper installation. We were able to secure new props and rebuild the thrusters to “like new” condition.

Because your bow and stern thrusters are in constant contact with sea water, we recommend that you inspect and service them twice a year to ensure that your yachting experience in close quarters and safe and stress free.

Caring for Your Hydraulic PTO Pumps

Our hydraulics team was recently contacted by a welding contractor at Lauderdale Marine Center to remove a PTO pump off a 150’ Palmer Johnson’s main hydraulics system so they could gain access to the ship to perform their work. What started as a fairly routine job quickly turned into something much more. The splines on the unit had seized, taking what would have been roughly a half day of work to several days.

Typically, we would construct an A-frame rigging to hoist the PTO pump out of the boat but in this case, we were forced to cut the unit apart and remove it in pieces. Because of this, the ship now requires a whole new replacement unit. Once it was uncovered that the first PTO pump could not be removed using standard procedures, the ship’s engineer had us remove the second pump to check the splines. Fortunately, the second unit did not have the same problem.

We highly recommend removing, refurbishing and re-installing these PTO pumps every three years or so for routine maintenance. Just like the top-end of a windlass which should be removed, cleaned and re-installed with new grease ever couple of years; PTO pumps need to be serviced to ensure that they do not experience these types of problems with seizing.

A proactive approach to maintaining these critical components of your hydraulics systems will pay big dividends and potentially save thousands of dollars in the end.

Bringing New Life Back to an Older 112’ Westport Yacht

We are seeing a growing number of new owners of older 112’ Westports. This “Made in America” production boat has a lot to offer but many of these vessels are purchased without a solid maintenance history. Nevertheless, their new owners/Captains still want to bring them back to life.  In order to do that, sometimes a total refit of the vessel is required.

One of these new owner refits spent a few months at LMC getting a full paint job, mechanical upgrades, interior work and hydraulic systems overhaul and refurbishing. Our capable team of hydraulic technicians was tapped to handle all the hydraulic projects.

Starting with the Naiad stabilizer system, we did a full rebuild including removing the shafts and bearings.  The entire stabilizer actuator system was also rebuilt back to new.  The stabilizer shaft had some corrosion in the lip seal area from sitting too long in salt water so our on-site machine shop, Straight Line Marine, performed a cladding repair.

We then moved on to work on the entire hydraulic central system where we performed a full hydraulic fluid flush, cleaned and pressure tested the heat exchangers and changed all the filters.

In the engine room, we found that we needed to change a large number of the hydraulic hoses.  Hydraulic hoses have a 10-year life and can cause huge problems when they fail on the high-pressure side so it is very important to inspect and replace them during routine service.

We also did a little work on the bow thruster, installing new seals in the lower leg, adding fresh gear oil and testing the hydraulic motor.

Stainless steel ring on main gear

Our team did a full rebuild on the single Maxwell 4500 windlass on the bow, down to the gear box including installing new seals and bearings.  As part of the rebuild, Straight Line Marine also fabricated new stainless steel rings for the main gears to help prevent future gear oil leaks around the lip seals. We also replaced the small Maxwell 2500 capstans in the stern with new electric units due to the cost of installing new versus re-building these smaller units.

We found the steering system to be in good shape.  There were no leaks on the cylinders so these were left alone.  We did, however, replaced a few hoses and upgraded some of the ball valves to stainless steel to help prevent future corrosion.  Finally, we changed the fluid and filters.

This was a big job from start to finish but our talented hydraulic technicians, supported by our in-house machine shop, were more than capable of tackling every hydraulic system from bow to stern and everything in between.

Repair, Service and Maintenance for Vosper Stabilizers

It is not uncommon to find Vosper stabilizers in many older yachts and ships. What is uncommon these days is to find a company that specializes in the repair, service and maintenance of the older units. VT Motion, the company that supplied Vosper stabilizers, was acquired by Naiad in 2009 and absorbed into its Naiad Maritime Group.

Increasingly, we hear from many ship’s captains and owners that when they seek to maintain their Vosper stabilizers, they are often urged or even forced to upgrade and replace these stabilizers with newer models. It seems that the major stabilizer companies are shying away from Vosper in lieu of recommending a major upgrade – an upgrade that can be expensive and time consuming.

At High Seas Hydraulics, we specialize in the repair, service and maintenance of all types of stabilizer systems including Vosper, Naiad, Quantum and others. If you are looking for expert hydraulic technicians to work on your stabilizer systems, whether older models like Vosper or newer ones on the market today, look no further than High Seas Hydraulics.


Rebuilding instead of Replacing a PTO Pump Can Translate into Big Savings for a Vessel

Our Hydraulics team was recently called upon to work on a PTO (power take-off) pump that was driven off the vessel’s main engine transmissions.

Removal of the pump was extremely difficult due to corrosion between the pump shaft splines and the coupling.  The corrosion was due to exposure to saltwater and normal wear and tear. In the marine business, the internal and external splines that make up the coupling usually reside on different pieces of equipment supplied by different vendors. The SAE Involute spline standards are the most commonly used for shaft diameters between ½” and 2”. The tolerances are loose enough to insure multi-vendor interchangeability while still providing torque transmission significantly higher than a keyed coupling. The tight fit avoids any lash and excessive wear in the splines over the life of the pump. There are many benefits in using spline shafts in place of a keyed shaft for this application. The spline connection offers a load distribution which is equal along the teeth sides enabling both to rotate together. Consequently, this load produces a longer fatigue life compared to the keyway drive.

In this case, the corrosion had damaged the spline surfaces and locked the two parts together. What would normally take a couple of hours, ended up taking almost two days to complete. Once finally removed, it was apparent that splines were damaged beyond repair.  The only solution was rebuilding the pump with a new shaft and the correct size splines.  Splines come in many different sizes and types, so replacement must be an exact match.

Once the pump was rebuilt, we re-assembled with the main engine transmission and installed it back in the boat. By rebuilding the pump, we saved the captain thousands of dollars.

Need Running Gear and Hydraulic Work Done on your Yacht – Work with Us

A 106’ Westport yacht was recently hauled at Lauderdale Marine Center for a variety routine maintenance projects including shaft work, bearing replacements and an overhaul on several hydraulic systems. To streamline the process and help the captain and crew better manage the project, they contracted with both High Seas Yacht Service for the running gear portion and High Seas Hydraulics to handle the hydraulics work.

Our running gear mechanics inspected the shafts to ensure they were straight and aligned and replaced the bearings and seals. Normal wear and tear associated with running the vessel and prolonged exposure to salt water makes this task a necessary evil for properly maintaining the boat. As seen in the adjacent photo, there was a visible gap where the cutlass bearing adjoined to the shaft.

We were also commissioned to replace the seals on the lower stabilizer fins. ABT Trac, one of the more popular brands, recommends changing the lower stabilizer fin seals every couple of years but at least every six years depending on use. The components on the stabilizer are constantly working except is absolute calm seas, so the wear and tear can be considerable. After dropping the fins, we proceeded to change out the old lower stabilizer fin seals with new ones, check the hoses and cylinders, then reassembling the units.

In addition to the routine maintenance on the stabilizer systems, we flushed the entire hydraulic system using the simple drain, filter, fill approach commonly referred to in our shop as a DFF. This type of flush is more of an “oil change” and is part of routine maintenance. It is not appropriate where a more serious condition such as water, metal particles or other contaminants are found in the oil. The process calls for draining the hydraulic tank, changing out the filters and refilling the tank with hydraulic fluid.

To round out the work on this Westport, we did an overhaul on the bow thruster, single Maxwell windlass, the boat’s heat exchangers and the hydraulic steering system which was slow to respond.

From running gear to hydraulics, our teams at High Seas Yacht Service and High Seas Hydraulics, make easy work of maintaining the systems that make your vessel safe and operating smoothly.

Refurbishing Hydraulics Parts for a 118-foot Yacht

When a 118-foot yacht was hauled out at Lauderdale Marine Center for a full refit including paint, our hydraulics team was called upon to refurbish some of the vessels hydraulic parts including its deck crane and side boarding ladders. After a thorough inspection, we removed the units and rebuilt them to “like new condition.” We stripped the units for paint and replaced all hydraulic hoses, cylinders and hardware. Once the other work is completed on the yacht, we will re-install the side boarding ladders and crane. The “new” side boarding ladders and deck crane will complement the look of the refitted vessel and provide years of service for future voyages.

Hydraulic Flush – When, Why and How

Every system on a mega yacht is important to the overall comfort and safety of the vessel and vessel’s using hydraulics are no exception. So how often should a hydraulic system, like those used for the steering, stabilizers, bow thrusters or windlass operations be flushed? To be on the safe side, a sample of the hydraulic fluids should be tested every six to 12 months or whenever the system is opened and potentially exposed to outside contaminants, you suspect that water may have infiltrated the tank or metal particles are found in the oil.

There are three methods for flushing a hydraulic system. The first is a simple drain, filter, fill approach referred to in our shop as a DFF. This type of flush is actual more of an “oil change” and is typically recommended for routine maintenance.  It is not appropriate where a more serious condition such as water, metal particles or other contaminants are found in the oil. In this scenario, we would drain the hydraulic tank, change out the filters and refill the tank with hydraulic fluid. Pretty straight forward.

The second method, known as a double oil and filter change, requires us to drain the hydraulic tank and fill with fresh oil that will be circulated using on-board system pumps. This method would be suggested under a few conditions; many years since last oil change, requirement to change oil types, minor discoloration of oil, etc.  This method involves an initial oil drain from the tank and low points in the system and filter change which can expel a large percentage of contaminants and degraded fluid. We would then fill the tank to the minimum level allowable to still safely work and circulate the oil until operating temperature is achieved. The oil is drained again and the filters changed for a second time before re-filling the hydraulic tank with fluid. For best results, the system should be drained as thoroughly as possible including the tank and manually cleaned.

The last option is more time consuming and costly and is used when there is known contamination of water or metal particles. This method often uses special high pressure pumps or power flushing rigs. Some of these pumps or rigs have directional valves that enable flushing direction to be changed which can assist in dislodging contaminants from dead spaces throughout the system. As in previous methods, the first step is to drain all old hydraulic fluid from the system and refill with a low viscosity fluid that will be circulated at high velocities to create turbulent flow conditions that equate to a Reynolds number of more than 2,000. This process would be repeated as needed until there is no longer any contaminants present in the filters or fluid. We would also remove, inspect and when necessary replace any hoses, cylinders and valves that are damaged.

Just like changing the oil in your car or any other mechanical device, hydraulic systems on your yacht need care and attention to keep them performing in peak conditions for years to come.

Repairing a leaking Heat Exchanger in a Bow Thruster HPU

We were recently contracted to inspect a leaking heat exchanger on a 130 foot Westport yacht docked at a local marina. The heat exchanger was part of the hydraulic power unit (HPU) for the ship’s bow thruster system.  The HPU consists mainly of a motor, a reservoir tank and a hydraulic pump. These units can generate a tremendous amount of power to drive most any kind of hydraulic ram or motor. They can also generate high temperatures. Most heat exchangers used in the marine industry are water cooled and use a water control valve to regulate the flow of water though the exchanger to keep the hydraulic fluid temperature between 64 and 68 degrees C (147 and 155 degrees F). It is important to make sure the adjustments for the water control valve are set properly to avoid rapid overheating.

This particular model was a shell and tube design.  As its name implies, this type of heat exchanger consists of a shell (a large pressure vessel) with a bundle of tubes inside it. One fluid runs through the tubes, in this case hydraulic oil, and another fluid, water, flows over the tubes (through the shell) to transfer heat between the two fluids. The set of tubes is called a tube bundle and may be composed of several types of tubes.

Upon inspection, we found that the fittings in the heat exchanger were not properly seated and the sealant used was not sufficient for the job. In order to remedy the problem, we needed to remove the heat exchanger from the HPU and send it out for servicing. In order to do this, we had to disconnect the hard pipe Stauff clamps above the heat exchanger in order to spread the pipes apart to remove the heat exchanger from the bilge. We also disconnected and installed caps and plugs in the hoses connected to the heat exchanger. We resealed the adapters and fitting upon re-installation, connected the hydraulic hoses, installed Stauff clamp supports and tested the unit for leaks.

The heat exchanger is back in operation and helping to ensure that the hydraulic bow thrusters are doing their job helping to maneuver this yacht in tight places.