Archive | Hydraulics

Flushing NAIAD Stabilizer Hydraulic Tanks

By Chris Brown on May 27, 2014 in Hydraulics

NAIAD Stabilizer Hydraulic Tank from the engine room

We have repaired, rebuilt or replaced NAIAD stabilizers on boats of all sizes. On the fin side we mainly concentrate on checking hydraulic cylinders for leaks, removing fins &shafts, inspecting bearings and replacing the lip seal. But there is also servicing required on the hydraulic tank in the engine room.

This was the case on a 100 foot Azimut that was in our yard. The hydraulic fluid was a burnt orange color as visible in the site glass. The hydraulic tanks for the NAIAD Stabilizer system uses salt water pumped through a heat exchanger to cool the hydraulic fluid. Over time, the heat exchangers in the units have a build-up of materials including limescale, barnacles and other marine encrustations that need to be flushed out.

The process involves draining the hydraulic fluid, removing the hydraulic tank from the engine room and removing the heat exchanger from the tank so it can be descaled. The process of descaling consist of running biodegradable acid through the inside and outside of the coils and flushing it with fresh water to remove any non limescale deposits and wash of the descaling liquid residues.

Once that process is complete, we pressure test the unit, re-assemble and reinstall it and add new hydraulic fluid.

Our experience with NAIAD Stabilizer systems allows us to deliver end-to-end service on the entire system.

One Stop Service for Multiple Projects on your Yacht

By Chris Brown on May 16, 2014 in Cylinders, Hydraulics, Stabilizers

Having a machine shop, Straight Line Marine; a running gear shop, High Seas Yacht Service and a dedicated hydraulics business, High Seas Hydraulics under one roof at Lauderdale Marine Center really pays off for our customers who are in need of running gear and hydraulics work done on their boats while they are hauled in the yard.

Hose coupling being attached according to specifications.

We just completed work on a 73 foot Palmer Johnson Sport Fisher – a very unique vessel. The NAIAD Stabilizer System required a complete rebuild from replacing the bearings to new seals, hoses and cylinders. We were able to take advantage of our specialized capabilities in the hydraulics shop to make the new hydraulic hoses with our Parker crimping equipment. We have the ability to make hydraulic hoses up to 1-1/4 inches in diameter. We were also able to re-build and stress test the hydraulic cylinders with the help of Straight Line Marine.

We also performed basic running gear service on this boat, removing and straightening the shafts in our machine shop and replacing the Lasdrop Dripless Shaft Seal system using our mechanics at High Seas Yacht Service.

Our customers have come to rely on the High Seas family of companies for one stop shopping to get the job done right in a timely and efficient manner.

NAIAD Shafts; Common Problems – Unique Solutions

By Chris Brown on May 13, 2014 in Hydraulics, Naiad, Stabilizers

Newly cladded NAIAD Stabilizer shaft

One of the most common problems we see on mega yachts is crevice corrosion and wear on stainless steel shafts, whether those shafts are propeller, rudder or NAIAD stabilizer shafts. Stainless steel shafts can be damaged by excessive wear in contact areas, such as bearings or seals due to long life or misalignment. Shafts can also be damaged from crevice corrosion or stray current corrosion.

The solution to these problems can range from cladding the existing stabilizer shafts or fabricating entirely new units. Cladding or shaft weld-over, is the process of repairing a worn or damaged area on a shaft. This type of work is done by our on-site machine shop, Straight Line Marine, which is the only shop in Florida that is ABS approved to perform this type of work on propeller shafts. Replacing a large NAIAD stabilizer shaft would cost thousands of dollars, depending on the size. However, the cladding repair is less than a thousand dollars.

This was the case on a 145 foot Trinity yacht that we were working on rebuilding its NAIAD Stabilizer System. When pitting or crevice corrosion becomes too extensive, it prevents the lip seal from establishing a tight fit thus allowing sea water in or oil to leak out of the system.

We removed the shafts, cladded them and installed new lip seals in the NAIAD Stabilizer and the owner was good to go.

Upgrading a NAIAD Stabilizer System for better Fit and Performance

By Chris Brown on May 13, 2014 in Cylinders, Hydraulics, Naiad, Stabilizers

NAIAD Stabilizer lower bearing housing

While performing routine lip seal maintenance on a NAIAD Stabilizer System on a 120 foot Custom Yacht; we found excessive amounts of corrosion on the external side of the housing. The corrosion was so bad we could not remove the plates in order to replace the seals.

An important component to the comfort and safety of any vessel, the principle behind NAIAD fin stabilization is to counteract the tendency of a vessel to roll with an equivalent and opposite righting moment applied in exactly the proper phase and proportion. These righting moment forces are typically generated from a pair of underwater fins, although other control surfaces are also available. Wave forces are thus prevented from aggravating the vessel’s natural tendency to roll.

Specially designed hydraulic press

Once the fins were removed from the NAIAD Stabilizer, the corrosion on the shaft and in the bearings was so significant that the shaft could not be removed using the most common methods. In order to get the shaft out, we built a special hydraulic press to drive the shaft out of the boat. With the shafts out, we then worked with NAIAD to upgrade the system to the next larger size unit.

Upgrading to the next size required a new housing which required fiberglass modifications to resize the hole in the hull.

What started out as a routine job turned into a complete replacement and modification to the yacht in order to guarantee continued high performance and comfort at sea.

Rebuilding BCS Trim Tabs for a Smooth Ride

By Chris Brown on May 13, 2014 in BCS Trim Tabs, Cylinders, Hydraulics

BCS Trim Tab

One of the more important features on any Super Yacht is the trim tab system for stability, speed and ride comfort in any sea conditions.

The working principle of a trim tab system is simple. By pushing one of the buttons on the control panel, the electro-hydraulic power unit receives an electric impulse which starts the electric motor. In turn, the latter makes the hydraulic pump start, being connected to it by means of a coupling. As the pump starts to turn, it sends an oil flow towards the side of the hydraulic cylinder corresponding to the desired movement (up or down), making the tab raise or go down. By pushing the button on the other side, the cylinder moves in the opposite direction.

As with any marine systems that come in contact with salt water, the trim tab system is subject to pitting and crevice corrosion.

We recently were hired to rebuild the BCS Trim Tabs on a 100 foot Azmit Yacht. The BCS Trim Tabs on this particularly vessel were not retracted in the up position and were left in the extended position too long contributing to significant crevice corrosion and pitting. When the cylinder is extended the rod is sitting in salt water – when retracted it is safely inside the cylinder in hydraulic fluid.

Crevice corrosion and pitting on BCS trim tab shaft

As part of the job, we fabricated new stainless steel rods in our machine shop, Straight Line Marine and rebuilt the BCS cylinders at High Seas Hydraulics.

After final assembly and installation back in the boat, the yacht is good to go for many more years of smooth sailing.

Hydraulic Accumulators Part Two – Re-installation of the Units

By Chris Brown on April 16, 2014 in Hydraulics

Earlier this month, we posted an article on the work we were doing on a hydraulic accumulator system aboard a 65M (213 foot) Palmer Johnson Yacht. As mentioned in the previous post, part of the job required us to relocate five of the eight accumulator tanks. We also had to run all new stainless steel tubing to re-connect the system to accommodate the new layout.

Hydraulic Accumulator Tank wall mounted to bulkhead

This job required us to do some creative bracketing fabrication work since we ran out of room to install all eight accumulator tanks in a very tight machinery space. To further complicate the matter, each tank weighs around 180lbs. when full, so this too needed to be taken into account when designing and fabricating the units.

As seen in the images in this post, one of the tanks was wall-mounted and bolted to the bulkhead while others were installed “condo” fashion, stacked one above the other.

“Condo” fashion mounting

Although the space was extremely tight and hard to work in, with a little ingenuity we were able to redesign, refurbish and relocate the hydraulic accumulator system to function in the space allotted and provide back-up power to the hydraulics for this yacht should they ever need it.

Machine Shop and Hydraulics Shop under one roof – convenience for the customer

By Chris Brown on April 15, 2014 in Cylinders, Hydraulics, Pitting

Hydraulic Cylinder Rebuild – Pitting on the Rod requires replacement

It is a fairly common occurrence for us to find pitting on hydraulic cylinders or shafts that we work on in our shop at High Seas Hydraulics. This is typically caused by corrosion from salt water, crevice corrosion or as a result of cheap stainless steel material used in fabrication. The lip seals on a hydraulic shaft or rod need a smooth surface or the hydraulic fluids will leak out causing a reduction in the performance of the units and, in this case, hydraulic fluid leaking into the ocean.

To fix this problem on large propeller shafts, we would perform a process called cladding at our machine shop, Straight Line Marine. Cladding or shaft weld-over, is the process of repairing a worn or damaged area on a propeller shaft or rudder shaft. Stainless steel shafts can be damaged by excessive wear in contact areas, such as bearings or seals, due to long life or misalignment. Shafts can also be damaged from crevice corrosion or stray current corrosion. Straight Line Marine is the only shop in Florida that is ABS approved to perform this type of work. Replacing a large shaft could cost up to $25,000 each shaft, depending on the size. However, the cladding repair is only a few thousand dollars. For smaller shafts like sailboat shafts or hydraulic cylinder rods, we would simply buy new rod material and scrap out the old rods.

Crevice Corrosion on Shafts will destroy a Lip Seal System

The convenience of having a machine shop Straight Line Marine and hydraulics shop (High Seas Hydraulics) under one roof ensures our customers that they can get the right level of expertise no matter how big or how small their needs.

Re-furbishing and Re-locating a Hydraulic Accumulator – takes the right tools and the right skills

By Chris Brown on April 10, 2014 in Accumulator, Hydraulics

Hydraulic Accumulator

We are working a complex hydraulic accumulator system that involves relocating a series of hydraulic accumulators on a 65M (213’) foot Palmer Johnson.

A hydraulic accumulator is a pressure storage reservoir in which a non-compressible hydraulic fluid is held under pressure by an external source. In this case the external source is plastic bladders filled with high pressure Nitrogen gas. An accumulator enables a hydraulic system to cope with extremes of demand using a less powerful pump, to respond more quickly to a temporary demand, or power the yacht’s hydraulic systems when the yachts main engine or pumps are not capable of providing the power.

A compressed gas accumulator consists of a cylinder with two chambers that are separated by an elastic diaphragm, a totally enclosed bladder, or a floating piston. One chamber contains hydraulic fluid and is connected to the hydraulic line. The other chamber contains an inert gas under pressure (typically nitrogen) that provides the compressive force on the hydraulic fluid. Inert gas is used because oxygen and oil can form an explosive mixture when combined under high pressure.

Hydraulic Accumulator with plumbing

As the volume of the compressed gas changes, the pressure of the gas (and the pressure on the fluid) changes inversely. As part of other work being done on the yacht, it was necessary for us to relocate five of the cylinders on this eight part system. Relocating part of the system required us to refabricate new brackets that hold the cylinders as well as re-plumb the hydraulic tubing to adjust to the new layout.

We also replaced a failed, leaking bladder in one of the accumulators before re-pressurizing each of the units to 1,250 PSI.

All this work requires very specialized equipment and knowledge to ensure the work is done right and that the hydraulic accumulator is ready when you need it most.

Rebuilding Stainless Steel Hydraulic Cylinders – Galling Problems

By Chris Brown on April 4, 2014 in Hydraulics

Welding stainless steel cylinders

We recently took a pair of stainless steel hydraulic cylinders off a swim platform on a hauled 130’ vessel Sunseeker. The cylinders needed to be rebuilt due to leaking hydraulic fluid. Rebuilding a cylinder is typically a fairly straight forward procedure, usually a few hours of shop time, when it is done right the first time.

Stainless steel hydraulic cylinders have a threaded stainless steel cap that is subject to galling and seizing during disassembly, if not probably lubricated with an anti-seizing agent the first time. Galling is caused by a combination of friction and adhesion between the surfaces, followed by slipping and tearing of crystal structure beneath the surface. This will generally leave some material stuck or even friction welded to the adjacent surface, while the galled material may appear gouged with balled-up or torn lumps of material stuck to its surface.When galling or seizing takes place, it becomes necessary to cut the barrels off the shafts of the stainless steel hydraulic cylindersto cut away the threads that are “welded”. This will result in many hours in the machine shop and extend the job and cost from a simple procedure to a much more time and money consuming process.

At times, the cost to custom machine and repair exceeds the cost of a new replacement. However, lead times and schedules often make the “repair vs. buy new” decision.

The moral of the story – be prepared for higher costs and longer delays getting back in the water if your stainless steel hydraulic cylinders are not done right the first time.

Muir Windlass – repairing the Wildcat – Gypsy – Chainwheel

By Chris Brown on February 21, 2014 in Hydraulics, Steering Systems, Windlass

Repairing the Muir Wildcat Gypsy Chainwheel

Removing the galled Muir gypsy

Another good customer with an 87′ Oceanfast had a unique problem with his Muir anchor windlass. Many years ago there was a mismatch between the metric sized chain and the imperial sized gypsy chainwheel (also known as a Wildcat in North America). The solution at the time, due to time constraints, was replacing the gypsy with an after-market gypsy (not Muir) that fit the existing chain. Unfortunately, the stainless steel gypsy was machined to fit the stainless steel Muir anchor windlass shaft without a bushing.

Within a short period of time the gypsy galled and seized to the shaft. We were able to pull the seized unit using hydraulics and pullers from our running gear shop.

Machined and pressed bronze bushing for Muir Windlass

Muir Windlass gypsy in the machine shop for bronze bushing installation

The final repair was an easy solution for our machine shop, Straight Line Marine, to machine and press in a bronze bushing. Good-to-go.

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