Friday, March 5, 2004

Gulf of Papua, New Guinea

Frames, Cranes and Winches!
In all of our slide shows about work on deck, you will typically see equipment being deployed and recovered using a combination of frames, known as a-frames, cranes and winches. While you may be familiar with a crane...do you know why we use cranes and what in the world are winches and a-frames?

Let's begin with a-frames. There are two hydraulic a-frames and a hydraulic boom on board that are equipped with pulley systems, called blocks, that allow lines or winch wires to run through these blocks in order to deploy and recover equipment. The a-frame is actually shaped like a slanted A; the boom is a retractable arm that extends out over the quarterdeck. The larger of the two a-frames is located on the fantail at the stern of the ship and we use this to deploy the chirp. The other a-frame is smaller and is used to deploy instruments such as the Jumbo Piston Core or other equipment from the starboard side of the ship. The a-frames and boom run on a hydraulic system and are quite easy to operate, but it is important to stay focused and listen for the resident technician or the scientist in charge of deploying and recovering equipment as they call out "a-frame in" or "a-frame out" and "a-frame stop." These directions must be followed immediately for the safety of workers on deck and the equipment.

Next we have cranes. There are three cranes that are permanently found on the R/V Melville. The largest crane is capable of lifting 5,000 pounds. The medium one can lift up to 2,500 pounds, and the smallest one located on the main deck lifts 2,000 pounds. In addition, on this leg of the cruise, Oregon State University has brought a crane as part of the Jumbo Piston Core equipment ensemble. The cranes have been used throughout the cruise for a variety of purposes. Back on the 17th and 18th of February, we used the 5,000-pound crane to move equipment for the Jumbo Piston Core, such as the Jumbo Piston Core, core liners, and weights. During the cruise, the smaller cranes were used to move equipment on deck, rotate the piston core and it's weights and deploy and recover equipment. In the previous cruise, the 2,500 lb crane lifted the small boat to and from the ship for small boat operations in shallower water.

The last piece of equipment I want to discuss is the winch. There are a variety of winches onboard including the trawl winch and two CTD winches. I imagine you are you asking what is a winch? Good question! Basically a winch is a large spool of steel winch wire. It looks like a large spool of thread lying on its side. The winch operator controls the movement and direction of the winch wire from a booth on deck. The booth has steel bars across the window to protect the winch operator from getting hurt should a winch wire break and snap back which could happen due to the amount of weight on the wire and because fraying of the wire causing a breakage could occur. A close eye is kept on the wire to be sure this doesn't happen and the deck is cleared during deployment and recovery of equipment, the most likely times for something to occur. The trawl winch is the largest winch and is situated towards the stern of the ship. The trawl wire is more than 1/2'' think and runs from the 01 deck, below to the winch room on the 1st platform, where you will find large spools of trawl winch wire. The Jumbo Piston Core descends, carrying a weight that is 4,500 lbs, and the other evening the tension on the winch wire when the piston core was pulled out of the seabed registered at 23,500 lbs!!! That's a lot of pressure!

Have a question? Send it to me via e-mail along with where you're from, to FlyRiverS2S@rv-melville.ucsd.edu. We can e-mail with the outside world...what other ways do we communicate at sea? Check back tomorrow to find out!

Today's weather and location at 1300 (thirteen hundred hours, military time for 1:00 pm)
Air Temperature: 27°C (81°F)
Water Temperature: 29°C (84°F)
Salinity: 29 PSU
Barometric Pressure: 1007.6 mb
Relative Humidity: 80%
Precipitation: 6.7 mm

Longitude: 8° 51.552' S
Latitude: 144° 16.441' E