Crew Boat Propulsion: From the Gulf to Africa

Morgan City Louisiana is one of those towns that builds on tradition but doesn't hesitate to try new ideas. One of its traditions is oil money and that has fuelled a steady evolution in boat design and construction in the surrounding bayous. Owners and builders are comfortable with boats as investments, but also as statements of their own philosophies. For a boat watcher, the results, particularly in choice of propulsion, are enticing. While one owner chooses all props, another chooses all jets and still another opts for a combination of props and jets. Respected elder of the crew boat fraternity Tom Kelly explains that when oil exploration was still concentrated around the bayous in the 1940s and 50s, there weren't many roads. As a child he went by boat to school. So there was a need for small boats to move workers to and from the rigs. As often as not these were converted fish boats. As the rigs moved off shore in the 1960s and 70s, speed became more of a factor.

Picking up on the historical account, Gulf Craft president Kevin Tibbs explains that there were two pioneers in aluminum construction in the area, Roy Breaux and Fred Seward, who employed plasma welding and improved alloys to build the first 90-foot boats. It was Fred Seward, who gave Kevin Tibb's dad, a crop duster pilot, the encouragement to start Gulf Craft back in 1963 at Patterson, just west of Morgan City. Norman McCall of McCall's Boat Rentals and Seacor Marine over at Cameron Louisiana, was one of the new builder's early customers.

"Dad's first aluminum boat was a twin Detroit 12V-71 powered 65-footer in 1969," explains Norman's son Joe McCall, "He had the 110-foot Elaine Marie McCall built with four engines in 1975."

Later McCall built a 120-footer and then in 1984, when business was slowing in the Gulf, he built his first Cummins powered 145-footer, the Paula McCall. As length was added to the hulls, builders had to take additional forces into consideration as these long hulls flexed considerably in seas and under loaded conditions. The aluminum handles this flexing well enough but quality control in the welds became increasingly important. In 1997 McCall's Seacor Marine took delivery of the 165-foot Hilda McCall powered by four 1300 hp Cummins KTA38 engines driving props. This boat is in response to the needs of newly developing oil leases 65 to 100 miles out in the Gulf of Mexico.

Three decades and over 400 hulls since their inception, Gulf Craft has recently delivered another boat, the 143-foot Marilyn McCall, to Seacor. Norman McCall prefers props on his boats that work in the Gulf as they perform better under loaded conditions. But with five of his 47 boat fleet working in Africa, he has come to prefer jets for that market. Gulf Craft designer Grant Pecoraro, explaining that due to the aft deck extension over the jet nozzles, the Marilyn McCall, delivered in the summer of 1997, has an effective waterline length of 135 feet.

Comparing two 135-foot boats, each powered by a total of 3200 hp, shows some significant differences in performances says Pecoraro. Both hulls have a 27-foot beam with an eleven degree deadrise on the transom tapering to 17 degrees midship. The only hulls variation is that the jet boat has a pair of fifteen-foot long fins below the chine to provide directional stability and prevent fishtailing when turning at speed. The jet boat, with Hamilton 571 series drives, will have a light running speed of 27 knots, compared to the prop boats's 24 knots. But add a load of 100 tons, and the jet's speed will fall to only 18 knots while the prop driven boat will maintain 22 knots.

Turning at 2100 RPM, the KTA19 will burn about 35 gallons per hour. Five of them burn 175 GPH. In the Gulf of Mexico heavy seas are common. When a prop boat slows in seas there is a resulting reduction in fuel consumed. Some of the jet's light running speed derives from the reduced drag with no shafts, props and rudders protruding from the bottom of the boat. This also gives them a reduced light-draft of 3.5-feet on the jet boat compared to six feet on the prop boat. It is this feature that prompts McCall choose jets for boats that Seacor will charter to work in western Africa where river ports are shallow and shipyard to haul boats with damaged props are few. Similarly the Norman McCall's choice of Cummins power for these boats recognizes the excellent maintenance free reputation of these K-series engines. There are boat designs that are primarily driven by government regulations and there are boats whose design is governed by form and function. The current generation of crew boats is of this later type. As such, each of these big Cummins powered pick-up trucks demonstrates a commitment to innovation by some of the finest designers, builders and mariners working anywhere.

NOTE: RUNNING SHOT OF THE MARILYN McCALL IS AVAILABLE. PLEASE LET ME KNOW BY E-MAIL, FAX OR PHONE IF YOU WOULD LIKE ME TO MAIL ON TO YOU. ALAN

For further information:

Kevin Tibbs
Gulf Craft, Inc.
Patterson, La.
Phone: 504 395-5254 Fax: 504 395-6259

Norman McCall
McCall Boat Rentals/Seacor Marine
Seacorp Marine
Cameron Louisianna
Phone: 318 775-5485 Fax: 318 775-7025

D.S."Red"Cunningham
Cummins Mid-South Inc.
Amelia, Louisianna
Phone: 504 631-0576 Fax: 504 631-0081

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