Click for next page ( 111


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 110
Issues in Ferry Service Management and Operation 113 to the intensive nature of the operation. Overtakes, small-craft identification, and marine con- ditions all require highly skilled crews. As an example, bow-diving is a recently identified con- cern that occurs when high-speed craft overtake a wave and then dive after cresting the wave. As a response to this concern, additional employee training has been suggested. Maintenance employees must be highly skilled, as vessel and engine technology continues to evolve into more challenging and complex systems. Some operators have found that mechanics with marine experience are highly valued due to their understanding of the implications of oper- ating machinery in marine environments. Vessel Technology Vessel technology is a critical factor in delivering reliable and competitive ferry service. In the selection of a vessel, issues of reliability, cost, and suitability must be balanced. A key concern is the relationship of a vessel's speed to its power and the influence of hull form on the speed-power relationship. In general, when length and displacement and hull form are constant, the required power increases rapidly with speed at a point called the "hump speed" (Working Group 41 of the Maritime Navigation Commission, 2003). One study provides an example in which a "70 ft. planing hull, driven at 50 knots, will require nearly 44 times the horse- power that the displacement hull requires at 10 knots even though the speed was increased by a factor of 5" (Savitsky 2003, p. 8). These large increases in the power-to-speed ratio can be mitigated, but not eliminated, by selecting proper hull forms. Hull forms, in general, fall into three preferred categories--mono- hull, multi-hull, and air-cushioned vessels. The preferred hull form for a vessel operating in a particular service depends on the operating conditions. Vessel Type Multi-hulls (especially catamarans), monohulls, and air-cushioned vessels all have their appropriate niche in the universe of ferry applications (Ad Hoc Ferry Transit Environmental Impact Panel, 2000; van Renen van Niekerk, 2000). Although catamarans have been used for centuries, they have become popular in the last 30 years as catamaran designers (mostly in Australia) have perfected catamaran design. Catamarans offer a more stable platform than the monohull, good maneuverability (resulting from propul- sion from two separate hulls), a wide platform that increases passenger comfort and reduces fric- tion with the water (resulting in higher speeds), and less draft and good wake/wash characteris- tics. Catamarans are used as small, fast boats in San Francisco and New York (for example, New York Waterways) and a catamaran will be used as a new vessel in Puget Sound in metropolitan Seattle. Larger catamarans provide high-speed service in New York and the San Francisco Bay Area (Larkspur and Vallejo routes). Figure 8-1 shows an example of a catamaran. Monohulls tend to cost less to operate than other vessel types, are less costly to build, and are the most common ferry vessel built. Large passenger and vehicle ferries are often monohulls, such as the Long Island-to-Connecticut car ferries and the Staten Island ferry. See Figures 8-2 and 8-3 for examples of monohull vessels. Hovercraft are specialty vessels that use an air cushion to ride above the water. They are used by the Canadian Coast Guard for search-and-rescue operations, while they provide pas- senger operation between Portsmouth and the Isle of Wight in the UK. In areas of low water depth, hovercraft allow for shore access without dredging and can reach very high speeds

OCR for page 110
114 Guidelines for Ferry Transportation Services Figure 8-1. Passenger-only catamaran. (above 45 mph). Hovercraft have a lower payload-to-power ratio than either monohulls or catamarans. There are other hull forms available and some are in commercial use (such as hydrofoils, sur- face effect ships, and so forth) but these multi-hulls, monohulls and air-cushioned vessels offer the most appropriate range of hull form options for ferry operators. Off-the-Shelf Designs The most successful ferry applications over the last 20 years have used proven, "off-the-shelf" ferry designs. These applications include the New York Harbor passenger-only ferries, new fer- ries in the San Francisco Bay Area, and passenger ferries to the islands of Massachusetts and Rhode Island. Even in cases where ferries are custom-built (which is common for vehicle ferries such as those used by the North Carolina and Washington State systems), components (engines, systems, and so forth) are proven, off-the-shelf, equipment. Figure 8-2. Monohull vessel.

OCR for page 110
Issues in Ferry Service Management and Operation 115 Figure 8-3. Passenger-only monohull vessel. Size and Stability A critical factor in ferry service is using a vessel that meets passenger demand, but is not too large. Vessels that are too large will incur unnecessary financial costs and will waste fuel. Vessels that are too small may result in denials of service to waiting passengers. Smaller vessels may also be uncomfortable for passengers due to inadequate space and/or inadequate ride quality. There are several methods to help operators balance capacity with demand and size vessels to ensure passenger acceptance. Sizing the vessel to achieve passenger comfort is a technical consideration and requires engi- neering analysis. For example, the Alaska Marine Highway System's design for new vessels spec- ifies "it will have 99% schedule reliability in Sea State 4" (Value Management Strategies, Inc. 2009). Managing capacity is a difficult policy issue. Jurisdictions previously considered access an "entitlement," and additional capacity was provided as demand increased (usually correspon- ding to and encouraging economic development). As funding decreased and costs increased, several jurisdictions now are taking a more "market-based" approach to transportation capac- ity. For highway-oriented ferry services, reservations are now a standard practice. This allows the ferry operator to spread out demand throughout the day and make better use of facilities and vessels. Some systems use peak-period pricing to further discourage travel during the peak times (and also to recoup the marginal cost of providing additional--and expensive--service during that period). Best practices for managing highway-oriented ferry capacity include the following: Establishing Level-of-Service standards (as is currently done in Washington State). Providing reservations for most sailings. Establishing peak-period fare/tariff surcharges. Managing fleet assets to have a mix of vessel types and capacities, maintaining a small reserve fleet to deploy as needed. For urban ferry services, ferry demand is usually related to the overall corridor demand within the metropolitan system. Since metropolitan systems are usually subsidized, best practices for urban ferries would include the following: Developing a service that has a competitive "per-trip per-seat" net cost to other modes. This approach allows ferries to charge a fare premium for a faster and more direct service.