When the San Francisco Bay Area Water Transit Authority told its consultants, Glosten-Herbert LLD, to design the lowest emission vessel possible for the Phase II ferry system in the post 2010 years, the task ultimately fell to subcontractor Seaworthy Systems, Inc., and its chief naval architect, W.A. (Bill) Wood. We had an interesting conversation with Wood from his office in Connecticut.
The New Super-Low Emission Ferry for Phase II of the Regional System, Starting in 2010
By Wes Starratt
When the San Francisco Bay Area Water Transit Authority told its consultants, Glosten-Herbert LLD, to design the lowest emission vessel possible for the Phase II ferry system in the post 2010 years, the task ultimately fell to subcontractor Seaworthy Systems, Inc., and its chief naval architect, W.A. (Bill) Wood. We had an interesting conversation with Wood from his office in Connecticut.
According to Wood, “The first thing we looked at was a small, fuel-cell powered ferry, and then WTA decided that they wanted us to look at a 35-knot, 350-passenger ferry with the lowest possible emissions. But that speed requires so much power that there is not room for fuel cells or storage facilities for liquefied natural gas. Furthermore, the chances are that by the year 2010, electric propulsion and fuel cells are not going to be perfected. Gas turbines were eliminated because they have a high initial cost, high maintenance costs, and high fuel rates. So, our choice was limited to diesels. And our task was to reduce the emissions of diesel engines to their lowest possible level, since we know that we can get the emissions for diesels way down by using the right technologies.”
The basic design for the Green Machine is for a ferry with a single passenger deck that would lessen air resistance and lighten the vessel. Solar cells could be installed on the open top deck to lessen auxiliary power requirements.
To design a hull, Wood worked with Don Burg and his firm, Air Ride Craft, Inc., on an air-assisted catamaran hull that would ride on a cushion of air created by a blower powered off the main engine. This air-assisted catamaran would reduce total power requirements and emissions for the 35-knot vessel by 21 percent over a conventional catamaran. Further reductions in power requirements for the hull design are possible at higher speeds so that the optimum speed of the WTA Green Machine is actually 40 to 45 knots. Because the vessel would ride on a cushion of air, surface piercing propellers would have to be designed for the ferry.
Propulsion systems for the boat had to meet or better the EPA Emission Standards for 2004-2007; so Wood and his team examined diesel engines worldwide and found a Series 2000 engine built by the firm WARTSILA in Finland that in its current configuration meets the EPA 2007 criteria. With that as a base, the team started adding “things” to achieve the lowest possible emission, as mandated by the WTA.
