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Restored Chesapeake skipjack gets E Motion hybrid drive
January 23, 2011 |
Ft. Myers Beach, Fl. A restored Chesapeake Bay skipjack, recently retired from the nation's last working sailboat fleet, is being repowered with twin-screw E Motion hybrid drive.
The boat's owner, Maryland developer Michael Sullivan, plans to use the 44' (on deck) Caleb W. Jones for educational excursions. He selected the E Motion system because the quiet operation of its two nine kw motors wouldn't interfere with lectures and discussions on board.
Shipwright Michael Vlahovich has spent the last three years rebuilding the 57-year-old skipjack at the Chesapeake Bay Maritime Museum in St. Michaels on Maryland's Eastern Shore. He launched the vessel last June in nearly completed condition and has been finishing up the E Motion system installation over the winter.
Vlahovich made the ribs and keel from white oak and the spars and planks from loblolly pine. "We cut the trees ourselves, sawed the planks and aged the wood for two years," he said.
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The Caleb W. Jones in St. Michaels MD
(Photos by Fred Tutman unless otherwise indicated) |
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| Mike Vlahovich has established the Coastal Heritage Alliance, a non-profit foundation dedicated to the preservation and advancement of commercial fishing family cultural heritage. |
| Left - Each motor sits on oak engine rails, with the shaft passing out through a heavy oak shaft log. |
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Known around the bay as "Eastern Shore mahogany," the spare, towering loblolly provides one of the Chesapeake's distinctive vistas, with long, thin trunks rising from the marshy horizon. The wood is heavy and prone to splitting if not carefully fastened, but it's otherwise, strong, durable and resistant to rot due to its resin content.
"For pushing a heavy wood boat like this, our high-torque motors with big props are a natural," says Dave Tether, CEO of Electric Marine Propulsion, dba E Motion Hybrids. "It's an ideal marriage of 19th and 21st century technologies."
Vlahovich built in two engine beds for the E motion motors, with the shafts exiting the bottom at some distance from the stern log. This separation between the props, combined with electric drive's precision motor control, should give the beamy boat exceptional maneuverability while backing and turning.
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"It's easy to vary prop speed independently or run one motor forward and the other in reverse," Tether says. "Plus there's that big skipjack rudder to help out."
The wide propeller placement is also ideal for regeneration under sail, he adds. "The props are out in the clear where the full force of the water flow can get at them."
Besides the twin nine kw motors, the E Motion system includes a 22 kw generator and two 144 v battery packs in parallel, each holding 12 Group 31 AGM batteries. The medium-size Group 31s were chosen for ease of handling. Total energy capacity is equivalent to a dozen 4D batteries. Propellers are a pair of three-bladed, 18 x 14s.
A half century of dredging
Built in 1953, the Caleb W. Jones dredged oysters for more than half a century from its home port at Deal Island on Maryland's Eastern Shore. It was still working in 2005, but like most skipjacks, fell victim to rising maintenance costs and falling oyster harvests.
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| Chestertown MD. Restored skipjack Elsworth under power with yawl boat pushing behind. (Wikipedia Commons) |
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Born to be a mast. The tall, straight loblolly pine is the tree of choice for skipjack spars and planking. (Wikipedia Commons)
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Motors installed on either side of the keel allow good prop separation, providing a turning moment to help steer the heavy skipjack under power or back it up in tight quarters.
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The skipjack's broad rudder combined with instantly reversible E Motion motors should considerably improve the heavy vessel's maneuverability. |
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The original vessel had no inboard engine, because Maryland limits motorized dredging to protect the oyster beds. Instead, skipjacks carry a dinghy-like, powered "yawl boat" to push them to and from the oyster beds in light winds and on the two days a week dredging under power is allowed. With the boat's oystering days behind it, Vlahovich was able to install E Motion hybrid drive as an inboard auxiliary.
Although the Caleb W. Jones is out of the oyster business, the quiet E Motion propulsion system will be ideal for its new role as an operating historical artifact. Especially during the summer, when the Chesapeake is often a glassy calm, electric drive will provide an unobtrusive source of power to keep the boat moving on windless days, while recreating the breezy quiet of life under sail. |
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A self-tacking jib is one less thing the busy crew has to handle while oystering. The mast, shaped from a single tree, has an octagonal cross-section below the boom for more secure fastening of cleats and step. |
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Beautifully wrought trailboards exemplify the craftsmanship Vlahovich puts into his work. |
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The skipjack is a classic example of a working vessel whose design and construction evolved from local sailing and water conditions, available materials and commercial requirements. (NOAA) |
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Skipjack Origins
The shoal-draft, centerboard skipjacks first appeared in the late 1800s as an inexpensive alternative to larger, round-hulled boats and log canoes following a crash in the oyster industry. With their straight keels, hard chines and athwartship planking with short - and cheaper - boards, skipjacks were easy to build at a low cost.
The large, self-tacking jib and enormous triangular mainsail could be handled by a small crew, yet were powerful enough in light winds to pull heavy dredges over the oyster beds and come about quickly without losing way. The centerboard, hard chine, low freeboard and broad beam - one-third the length on deck - made a wide stable work platform for maneuvering the unwieldy dredges and culling the oysters to remove rocks, mud and shells.
Oddly, the oldest remaining skipjack, Rebecca T. Ruark, built in 1886, has a rounded hull with fore and aft planking. She was certainly one of the first - if not the first - skipjack built and may represent a transitional stage from the rounded hull shared by the bay's other sail-powered fishing vessels - bugeyes, pungies, schooners and sloops. |
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| Carbon-titanium need not apply. Galvanized strap and rigger's blocks are a better fit for the waterman's budget. |
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| Port motor. The 9 kw model consists of two 4.5 kw motors inside a single casing and fixed to a single shaft. |
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| One of two 144 v battery packs connected in parallel. Group 31 batteries were selected for ease of handling. |
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