1500 Miles Offshore

Here are some of the different things we have been working with over the past few days while traveling through the middle of the southern Atlantic Ocean.

Lubricating Oil Purifier inspection & overhaul. Every 4000 running hours (about 5 months) these devices are dismantled, cleaned, and refurbished. We replaced all seals and O-rings and inspected the components.

The purifiers run continuously in order to separate particulates and moisture from the engine lubricating oil. This way, the oil does not need to be completely changed periodically as in a car engine. Similar purifiers are also employed in the fuel oil system to ensure that the fuel is untainted before being supplied to the engines.

The devices separate the lube oil from water and particulates based on their differences in density. When the purifiers spins at about 9000 RPM, the heavier contaminants accumulate on the outside of the chamber while the lighter lube oil remains closer to the center.

Steam valve repair. This valve is from the HFO heating line for the forward tanks. Heavy fuel oil must be heated in order to reduce its viscosity enough to be efficiently pumped and supplied to the engine when burning it as a fuel.

This globe-type valve operates by throttling or stopping the fluid flow through to an orifice within the valve. The leaking steam had eroded pits in the sealing surface, possibly because it was not shut tightly. A new surface had to be created using the lathe, a grinding tool, and various lapping compounds.

Pulling and cleaning one of two main seawater strainers. This acts as a coarse filter for all water entering the ship for cooling and ballast purposes. There were lots of yummy aquatic creatures residing in it and the smell will not be easily forgotten.

Calibrating gas detectors with a bag of methane/nitrogen mix. These detectors protect against dangerous gas build ups that could occur in the event of a leak. They sense the concentration of methane in the ambient atmosphere and are integrated with the ship's automation system.

Speaking of natural gas, this is a gas admission valve for the dual-fuel engines. When the engines are operating in gas mode, these valves control the supply of fuel gas to each individual cylinder. The duration and timing of the gas admission is controlled electronically by the engine software. Controlling the amount of gas allowed into the cylinder acts as the throttle of the engine and the flow is adjusted to maintain a speed of 514 RPM as the generator load changes.

Conversely, when operating in diesel mode, fuel injection is controlled mechanically by the governor (shown). This hydraulic device adjusts the position of the fuel rack (the throttle) in response to small fluctuations in engine speed. The fuel rack controls the amount of fuel supplied by the injection pumps to the nozzles in the cylinder heads.

Cross sectional view of a Wärtsilä 8L50DF engine, of which the ship has two.

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In other news, we were visited by a whale one sunny afternoon.

Although the ship was cruising at 17 knots, it had no problem keeping up and followed us for about five minutes.

 

By chance we also happened to cross within a mile of another ship in the middle of the ocean. The tanker was on a perpendicular course with us; probably heading towards the southern tip of Africa.

Even though we are without a landscape, there is no shortage of spectacular natural scenery. Sunsets and sunrises ignite the sky and clouds appear as landmasses at the edge of the horizon. When clear nights coincide with a new moon the stars appear as numerous as grains of sand on a beach.