A Shift in Thought Page 2

A Shift in Thought

Part 2: I watch with slack jaw as the shaft just goes fluidly in one direction and then the other, no jerky motion, stoppage, or clunk.

By Capt. Patrick Sciacca — January 2003

 More of this Feature

• Part 1: Twin Disc
• Part 2: Twin Disc
• Part 3: Twin Disc

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• Engine Editorial Index

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• Twin Disc

It certainly sounded good to me, so last summer I tried out the QuickShift at Wentworth By The Sea Marina in scenic Portsmouth, New Hampshire. Johnson and I met up with Capt. Jim Fox, who had been running the 48-foot Sea Ray demo boat Lady B for about six months and who confided to me, “Until I got involved with this project, I didn’t think much about transmissions.” He said he’d always figured the boatbuilder would just match up certain engines with certain transmissions and that would be the end of it. I agreed. Most boaters do go with the boatbuilder’s recommendations and never think twice, and rightly so. Builders go through an enormous amount of testing on demo boats before finalizing a standard gear list. But this apparently radical transmission would soon give me a reason to think about shifting my own thoughts on the subject.

After powering up the twin 660-hp Caterpillars, Fox tells me he wants to show me something before we leave the dock. I duck down into the engine room, and he shifts the boat’s port engine from full forward to full reverse. I watch with slack jaw as the shaft just goes fluidly in one direction and then the other, no jerky motion, stoppage, or clunk. “Interesting,” I think. “But doesn’t going full forward to full reverse put added strain on everything in the driveline?” I ask. “No,” he replies, adding that it’s actually lessening the impact on all the couplings and whatnot because the energy is being distributed slowly and evenly. “If this holds true, then the QuickShift transmission may actually extend the life of the driveline, and may even save on repair costs,” I think. But the real test is yet to come.

Johnson and I join Fox on the flying bridge, and Fox tells me he likes to run Lady B in the optional Express mode (available only with the EC-251 electronic controls), which provides a trolling mode for the first 15 degrees of throttle travel, then allows full rpm range. To me, this seems the best fit for close-quarter maneuvering. This demo boat has the three-mode system, which also contains a Cruise mode that operates as a normal electronic control and transmission would (complete with lurching) and the Troll mode that allows the boat to operate at a couple of knots or less. A two-mode system with just Cruise and Troll is also available.

Next page > Twin Disc, Part 3 > Page 1, 2, 3

This article originally appeared in the January 2003 issue of Power & Motoryacht magazine.

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