to reduce or eliminate cargo-related accidents on a deck bearing a load of hundreds of tons over a hull likely to be pitching in heavy seas, an additional design feature bound to find favor with crews is a "safe haven" on deck with multiple entryways -- a place to hide if things get tricky on deck, made of three-eighths-inch steel plate welded to the underside of the upper cargo rail and to the deck. There are smaller details to consider as well, since failure to consider them could make them anything but small. "I've seen so many fires." said Mr. Schubert, "associated with fuel lines or oil lines being attached to something that vibrates during the normal operation of a boat. So we went through all the brackets that hold oil filters or fuel filters, and verified that they would not vibrate. We'd verify that all the piping is really secured, and won't break in the night because of vibration fatigue." And because even the most automated vessel really isn't automatic, steps were taken to encourage everyone to be in the right place. "Dripless packing glands for the propeller shafts improve the engine room considerably," said Mr. Schubert, who also cited the attention given to engineroom ventilation "to make it more hospitable. The cooler things run, the longer they last -- and the more people will go in to check stuff in there." Did somebody mention traditions at Harvey Gulf International? "We haven't spilled a drop of oil overboard," said Mr. Guidry, "we haven't had an accident." That's pretty good going, considering maritime work generally and the special character of the Gulf. It's something the splendid Harvey Gulf supply boats appear calculated to uphold. Harvey Discovery's rescue boat, a six-man Norsafe, is routinely tested to ensure readiness for its mission. Here AB John Keller takes the high-speed craft around the waterways of Fourchon to prove its mettle. (Photo: Don Sutherland) The 240x56x18.5-ft. Harvey Explorer, representing the first class of Harvey Gulf OSVs, is equipped with numerous in-house innovations to maximize comfort, safety, and efficiency. (Photo: Don Sutherland.) end. It constantly monitors the main engine fuel burn and calculates an efficiency factor based on such real-time operating conditions as speed. This allows the charterer to instruct the vessel to operate either at its most economical speed, assuming the voyage is not time-critical, or at maximum speed when time is of the essence. Lower fuel consumption from the bow and stern thrusters while in DP mode, along with lower noise levels, are accomplished through a three-speed engine control, matching RPMs to environmental conditions at any particular time. The thrusters are direct-driven from their respective engines, in another bid for operating efficiency. "Most of the thought behind re-engineering our thrusters," said Mr. Schubert, "was to reduce noise and vibration levels in the accommodations area of the vessel, directly over the bow thruster area. The fuel savings are a bonus for our customer." Automation on the High Seas The Harvey OSVs are equipped with automated cargo discharge systems operated from the pilot house. They control 196 individual valves and a dozen individual pumps operating the various fluid systems and the air compressors serving the bulk mud discharge system. The operator specifies which valves are to open or close and which pumps or compressor are to be switched on or off, whereupon the system generates a flow path on its monitor screen. Prior to complying with the operator's command, the system displays the consequences of the flow path, and requests approval. The elimination of spills and cross-contamination of products is the fail-safe goal. The procedure occurs in the pilot house, where the skipper is on-hand immediately to make any decisions about a cargo transfer operation. The DP-2 designation generically specifies two of everything required to continue operating in DP mode, a redundancy factor correcting for the failure of any part of one of the DP systems. The Harvey boats add relative position sensors or "DARPS," and RAYDIST which permits the vessel to maintain station even with the loss of both primary satellite positioning systems. "More importantly," said Mr. Schubert, "it allows the vessels' D-P controls to `sense' the actual location of the platform or floating drilling rig relative to the vessel." The dual rudders of the vessels can be independently positioned to enhance DP capability, improve response time, and reduce the required draft. For all the automation, arrangements were made with suppliers and integrators to simplify taking back manual control of the vessel if required. "I've encountered a lot of accidents," said Mr. Schubert, "where the DP system lost one of the reference points, like the satellite, and the vessel started drifting away or into a rig. Usually the captain would have to manipulate seven different switches to go into manual mode -- in an emergency situation it was really a heavy workload to do properly to take over control of the boat. We got it to where he has to manipulate only three switches to take back manual control of the vessel in the event of emergency." The cargo deck of the 240s is equipped with 66 tiedown points, 88 on the larger boats, calculated to permit tying each piece of the load from an optimum position. While an objective of this design is December, 2006 · MarineNews · 21
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