Wartsila Seal Bladder System Tested on Shaft
Many of the large “Class” vessels have seal systems such as Wartsila or Duramax that have an emergency inflatable bladder. The system is basically an inflatable bladder (like a bicycle tire tube but far more durable) that is housed just aft of the ships seal system. If there is damage to the seal, air pressure is applied from a ship’s compressor or simple bicycle pump to inflate the bladder. The air press causes the bladder to tighten around the shaft and slow the leak to a small drip. If the system is operating properly it should maintain air pressure for hours. However, the systems are not designed to withstand the friction of the shaft turning. Usually the vessel has a shaft brake system to allow movement with one engine without the “down” shaft from turning.
We have just completed a 5 year ABS inspection on the running gear on a 121′ Heesen. We removed the Wartsila seals and tested the inflatable bladder at the shop. The picture below shows the set-up on the shaft (145 mm shafts). The video above shows the inflation of the bladder using a simple bicycle pump. It is a good thing we tested the bladder. We found the fittings on one side to be loose and would not hold air pressure for more than a few seconds.
Confidence at sea comes from careful preparation and testing of all the ship’s systems.
- Wartsila EL Shaft Seal with Compression Tool
Wartsila Shaft Seals are often found on larger Class Yachts. The principal of the system is based on a face seal created by a phenolic ring riding on a graphite base. The phenolic ring does wear with time and use similar to a brake pad.
- Soundown Thrust Element – Old Deterioration vs. New
Soundown Vibration Dampening systems are usually found on older large yachts. This one came out of a 123′ Feadship. The center stud has two urethane “Coupling Thrust Elements” that have a finite life and should be checked every 10 years. The Thrust Element in the photo was 50% deteriorated and came out in small pieces. The picture shows the remnants on the bolt washer and in the part. The new urethane part is also shown in the picture.
- Cladding or Weld-over on Aquamet shafts
From time-to-time we come across shafts that have suffered from a bad case of crevice corrosion. Crevice corrosion, unlike galvanic corrosion, comes from stagnant water that changes chemical composition with time. We find crevice corrosion on shafts in the seal area, bearing area and inside the stern tube. Usually the crevice corrosion is not found on the part of the shaft exposed under the boat since tidal flow keeps the water moving and “fresh”. Wiki has more explanation here.
- Running with cool bearings
A week ago I got a call from a Captain on a 120′ Sovereign that was experiencing a very troubling vibration problem. He had already had a vibration analysis company survey the boat and had another yard pull the shafts and replace all cutlass bearings. The sound was coming from the port side shaft and was described as an audible “zupe….zupe….zupe”.
Stern Tube Cutlass Bearing Completely Worn
Here is another case of poor water cooling for a cutlass bearing. This cutlass bearing came out of the forward end of the stern tube on a 123′ Feadship. The cooling line that runs to the stuffing box keeps the packing cool and provides water to the two cutlass bearings located in each stern tube.
Unfortunately, the cooling line was blocked closer to the engine and the stuffing box and bearing ran dry for a short period of time. It does not take long to completely wipe out a cutlass bearing when running dry.
Since the vessel is now in the yard for more extensive service we are removing the running gear from both sides (three shafts per side coupled by SKF Hydraulic muff couplers) and performing a complete engine alignment.
Looks like we will need a few more of the large sleeves for the SKF Muff Couplers (as seen here on a past project).
Tides Lower Bearing and Seal Assembly
A past customer called with an emergency problem. His 61′ Queenship was taking on water from the rudder seals and needed to be hauled and serviced right away.
The system was an old version Tides rudder bearing and seal Type “D” and the problem was four-fold.
The old seals were worn.
The upper bearing in the shelf had come loose and was allowing too much play in the rudder stock.
The lower bearings were out of specification allowing too much rudder stock movement. Tides allows up to .025″ before replacement.
There were no spares on the rudder shaft to allow for temporary repairs.
Queenship 61' After Rudder Bearing Repair
After haul-out we dropped the rudders and inspected the bearings. The upper shelf bearings were in tolerance and OK once re-secured in the proper aligned position. The lower bearings required replacement since they were beyond the .025 wear specification from Tides Marine. Replacement was relatively simple with the Tides Type D system. The new bearing and seal assembly threads into the existing tube that is already glassed and bedded into the hull.
Final launch and check – dry bilges and solid rudders.
Hydraulic Teignbridge Propellers
Hydraulic propellers and couplers show up from time-to-time. We found both on the 87′ Oceanfast project. Hydraulic propellers are installed on shafts with a very shallow or flat taper. There are no keys or keyways in the shaft. Hydraulics are connected to the ports and inject a high pressure layer (up to 40,000 PSI) of hydraulic fluid between the prop hub and shaft. The hydraulic pressure expands the prop hub and creates a layer of fluid that allows the prop to slide off the shaft (actually it goes with a bang similar to popping any mechanical prop).
Laser through to Engine Room Bulk Head
Deck Targeting is an absolute requirement for some yachts to ensure the vessel is block on land in the same shape as in the water. Light weight vessels that do not have a strong keel structure will “hog” when picked up in the travel lift slings. If the yard crew blocks the vessel with this hog shape (higher at the sling points and lower on the ends) then any attempt to run an optical scope alignment will fail.
The answer is a laser deck target, double or triple beam. The laser is set while the vessel is in the water. Measurements and marks are made prior to haul-out. Once on land the blocking crew are instructed by High Seas to make blocking and jack-stand adjustments to recreate the measurements exactly.
Sometimes the laser needs to be raised up to shoot all the way to the forward engine room bulk head. A tripod gets the job done as seen in the photo.
This project will involve a complete engine alignment and running gear overhaul on an 87′ Oceanfast. This particular vessel is a full keel design and very rigid. The laser deck target showed that there was almost no flex or hogging during the haulout. It is great to know the vessel is blocked accurately so that we can proceed to the optical scope alignment and make changes to the engine or strut alignments if necessary.
Palmer Johnson Designed Prop in Front of Strut
You don’t come across this design too often.
This 90′ Palmer Johnson was one of only a few built with a novel design. The prop is in front of the strut. The concept allows cleaner water to enter into the prop thereby increasing the prop’s efficiency.
In order to keep the vessel running smoothly our machine shop carefully mated the stub shaft to the prop face. Cutlass bearings are a challenge since it is difficult to get clean water running just aft of the prop in the skeg/strut.
