High Seas Yacht Service » Oceanfast

New Generator Mounts Stops Vibration

Chris — Tue, 06 Jul 2010 14:28:33 +0000

New vs. Old Generator Mounts

One of our good customers in a 10 year old Oceanfast had a big problem with generator vibrations. Upon inspection it was clear that the old generator mounts had “pancaked” and lost all of the isolation properties. (See photo for old vs. newly installed mounts).

After consulting with Tides Marine on new Isoflex Mounts a new engine mount was recommended to fit the application. The installation was very simple since the Isoflex mount used the exact same bolt pattern – no drilling or other modifications required. All 8 mounts on two generators were changed in one day keeping labor cost very low.

As soon as the new mounts were installed the crew could not wait to fire up the gennies and run a test. The initial feedback was excellent; “huge reduction in vibration – maybe 75%” was the subjective comment from the Captain.

The cost of the mounts is very reasonable and labor cost was low. This is an easy upgrade for your vessel. If you have mounts that are 10 years old and you are in the area give us a call and we can turn a small job into a big improvement.

Shaft Cladding to Repair Crevice Corrosion

Chris — Wed, 27 Jan 2010 11:23:23 +0000

: 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.

Crevice corrosion on the shaft in non-bearing or seal areas are OK and usually left alone. However, if the corrosion is in a cutlass bearing location or seal/packing area it must be repaired. The pitting will cut up a new cutlass bearing in a short time and will not let a shaft seal properly seat and keep dry.

To repair the area, as we are doing on this 87′ Oceanfast, requires machining down the shaft (as seen to the left of the machinist shoulder) and then filling in the area with a welding bead. This is called a weld-over or cladding (more pics here). In this picture there were two different areas requiring repair. The area pictured is right under a half cutlass bearing. The welded area is a smaller section where the Tides seal will run.

Once the weld is complete the shaft will require straightening (600 degree welding will bend the shaft regardless of precautions), then a final machine and polishing. I challenge someone to come to the shop and find the weld when finished – it blends in that well.

Hydraulic Teignbridge Propellers

Chris — Mon, 11 Jan 2010 01:28:06 +0000

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 Deck Targeting

Chris — Mon, 11 Jan 2010 01:07:58 +0000

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.