High Seas Yacht Service » Heesen Yachts

Schaffran Propellers – Hydraulic Fit

Chris — Tue, 03 Aug 2010 12:51:34 +0000

Schaffran Propellers after reconditioning

On a recent shaft job for a 121′ Heesen we had to remove the Schaffran props pictured here. If you are in the commercial vessel business their props would be small compared to tugs and freighters. However, in the 100 – 180′ mega-yacht business there are hefty units coming in at over 1,000 pounds each with a hub length over two feet. These props will push a 121 footer over 30 knots with twin MTU 4000 engines.

The Schraffran propellers are also hydraulically fit on the propeller shaft. There are no keys or keyways cut into the shaft. It takes specialized hydraulic equipment capable of up to 40,000 psi to expand the propeller hub and slide it off the taper.

Having hydraulic fit propellers eliminates one of the weakest points in a propeller shaft – the keyway. Great care must be taken with the removal and installation to make sure the shaft taper is not scored and the prop is “driven-up” on the shaft the correct distance.

High Seas has all of the specialized hydraulic tools and fittings to do the job right. If you are responsible for a vessel make sure you know if you have hydraulic propellers or couplers. This should be reviewed carefully with the contractor working on your running gear to make sure they are prepared to do it correctly.

Emergency Shaft Seal Bladder Systems

Chris — Mon, 15 Feb 2010 16:46:21 +0000

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.

Another Wartsila Shaft Seal Adjustment Tool for ManeBar Seals

Chris — Sat, 06 Feb 2010 15:59:11 +0000

: 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.

This seal is out of a 121′ Heesen that is going through a normal 5 year ABS inspection. The running gear is completely removed, cutlass bearings replaced, engine and strut alignment checked, shafts, props and couplers are checked in the machine shop. Finally, the shaft seal system is removed for inspection. This particular seal is the EL ManeBar model. All the components were checked against the manufacturer’s specifications and found to still be acceptable to reinstall in the vessel.

Once the shafts are installed the system must be adjusted or compressed to tolerance in order to create a dry shaft seal system. I wrote about a tool for a different Wartsila Seal model a few months ago. Wartsila has designed their seals with a special installation tool in order to get an even and controlled compression. For the EL Shaft Seal the tool is comprised of threaded rod, a “hook block”, nuts and washers. Each vessel with Wartsila Shaft Seals should have the tool on board. Unfortunately, since the tool is only used once every few (or five) years it is often hard to find. In this case, our machine shop fabricate this tool with Wartsila’s support and permission. A special thanks to Steve and Brian at Wartsila for their excellent customer support.