3 U.S. Fleet Case Studies (Phase 1)

3.1 The Flying Cloud and Lightning (Harbor Express)
The Flying Cloud and Lightning were built at the Gladding-Hearn Shipyard in Somerset, Massachusetts in 1996 and 1997 for the Harbor Express Company. Harbor Express currently operates the boats for the new owner, the Massachusetts Bay Transit Authority (MBTA), in service between Quincy and Hull, Massachusetts, and downtown Boston and Logan Airport.

The particulars of these boats are: 23.3 meters (76.4 feet) in length, 30 knots service speed, 3 crew (captain and two deck hands), 1930 horsepower with waterjet propulsion, 149 passenger capacity, and certification for “Limited Coastwise” service. The Stability Letters rate the boats for service in partially protected waters. They are designed as “bow loaders”, that is, the vessel’s bow contacts the dock at approximately equal freeboards (height above water to deck) and passengers board directly after the crew opens the gates on the boat (see Figure 3-1). The passengers then proceed to the cabin through double weathertight doors in the forward bulkhead (see Figure 3-2). These doors do not have coamings and have been accepted by the Coast Guard as providing equivalent protection as coamings would.

Figure 3-1
Bow Loading on the Lightning, August 14, 2003

Figure 3-1 Bow Loading on the Lightning, August 14, 2003

Figure 3-2
Access Through the Passenger Cabin Bow Doors

Figure 3-2 Access Through the Passenger Cabin Bow Doors

3.1.1 Description
The forward passenger cabin doors are approximately 36” wide each, and are symmetric about the centerline in the forward bulkhead of the passenger cabin, their inboard extremes about 18” apart (see deck layouts, Figures 3-3 and 3-4, and photograph, Figure 3-5). The doors are required to be closed at all times while the boat is operating.

Figure 3-3
Passenger Cabin, Plan View

Figure 3-3 Passenger Cabin, Plan View

Figure 3-4
Flying Cloud Bow Doors, Deck Plan

Figure 3-4 Flying Cloud Bow Doors, Deck Plan

Figure 3-5
Bow Doors, Flying Cloud

Figure 3-5 Bow Doors, Flying Cloud

The status of the bow doors’ compliance with the relevant ADAAG door specifications is as follows:

  • 4.13.5 Minimum clear opening of 32 in (815 mm) with the door open 90 degrees.
    Status: The clear opening of each of these doors exceeds 32”.
  • 4.13.6 Minimum maneuvering clearances at doors that are not automatic or power-assisted shall be as shown in Figure 25.

Status: Figure 25(a), “front approaches – swinging doors”, pertains. The maneuvering space on the “pull side”, that is, on the weather deck, complies. The maneuvering space on the “push side”, that is, inside the cabin, does comply also. The lateral space requirement of 12 inches on the handle side of the door does not pertain because the door is not the “closer and latch” type.

The floor or ground area within the required maneuvering clearances shall be level and clear. The deck line has “sheer” in this area, that is, it declines towards the aft end; this angle also changes with the static attitude of the boat (known as trim and heel) as well as the dynamic motion (pitch and roll). Even in the static standard load condition, the bow doors on these boats do not meet the letter of this specification.

  • 4.13.8 Thresholds at doorways shall not exceed 3/4 in (19 mm) in height for exterior sliding doors or 1/2 in (13 mm) for other types of doors. Raised thresholds and floor level changes at accessible doorways shall be beveled with a slope no greater than 1:2.

Status: The doors meet this standard.

  • 4.13.9 Door Hardware. Handles, pulls, latches, locks, and other operating devices on accessible doors shall have a shape that is easy to grasp with one hand and does not require tight grasping, tight pinching, or twisting of the wrist to operate.

Status: The hardware for each of these doors includes two “dogs” (levered closing devices which secure the door at several points around its perimeter, operable from both sides of the door) in addition to the conventional door handle. These are intended for operation by the crew only and would not be ADAAG compliant in any case for the reason, among others, that one is mounted higher than the guidelines allow. These dogs are required for proper weathertight sealing of the door.

  • 4.13.10 Door Opening Force. The maximum force for pushing or pulling open a door is 5 pounds.

Status: The design specifications for these doors do not include opening force; the specification does not apply to this exterior hinged door.

The doors rest on a very short sill plate (less than ¼” high) and are bounded on both sides by series of aluminum plates, laid transversely, with narrow (3/16”) intervening gaps for drainage (see Figure 3-5). Water entering those gaps drains into a segregated cofferdam structure below and then directly to the ocean between the catamaran hulls.

Figure 3-6
Drainage Detail Forward of Doors, Lightning

Figure 3-6 Drainage Detail Forward of Doors, Lightning

The deck structure in the passenger cabins of Lightning and Flying Cloud has one important feature: it is completely separate from the watertight envelope of the catamaran hulls. The weather deck (or main deck) is, in this case, the plating and structure forming the top of each hull and is watertight, not weathertight. Transverse structural frames connect the hulls, and all the superstructure, passenger cabin and deck included, sits on top of those frames. Figure 3-6 shows an open access cover and the manhole beneath and illustrates the separate deck structures. All service connections between hull and superstructure (e.g., wiring and piping) have watertight hull penetrations and the spaces within the hulls are unmanned (i.e., there is no regular access to them during operations). Access therein for maintenance and repair is via non-tight hatches in the passenger deck leading to watertight “manholes” in the hull tops.

Figure 3-7
Access to “Main Deck” Manhole, Lightning

Figure 3-7 Access to “Main Deck” Manhole, Lightning

The passenger cabins on these boats also have sliding doors toward the stern end of the passenger, both port and starboard, providing access for the passengers to the weather decks and stairways to the upper deck. There is very limited weather deck space on the cabin deck, essentially providing landings for the stairways (which are not accessible). The opening force of this door is not known.

The status of the aft sliding doors’ compliance with the relevant ADAAG door specifications is as follows:

  • 4.13.7 Minimum clear opening of 32 in (815 mm).

Status: The clear opening of each of these doors exceeds 32”.

  • 4.13.8 Minimum maneuvering clearances at doors that are not automatic or power-assisted shall be as shown in Figure 25.

Status: Figures 25(d & e), “front” and “slide side” approaches for sliding or folding doors, pertain. The maneuvering spaces for both approaches are not sufficiently wide, because of the proximity of the snack bar inside and the deck edge on the weather deck.

The floor or ground area within the required maneuvering clearances shall be level and clear. The deck line has less “sheer” in this area, but the deck’s angle changes with the static attitude of the boat as well as the dynamic motion, as for the forward doors.

  • 4.13.8 Thresholds at doorways shall not exceed 3/4 in (19 mm) in height for exterior sliding doors or 1/2 in (13 mm) for other types of doors. Raised thresholds and floor level changes at accessible doorways shall be beveled with a slope no greater than 1:2.

Status: The sliding doors do not meet this standard on either count. The doors’ tracks are 1” X 1” X ½” angles welded to the deck, slightly exceeding the height maximum. There is no beveling of the deck on either side of the tracks.

  • 4.13.11 Door Hardware. Handles, pulls, latches, locks, and other operating devices on accessible doors shall have a shape that is easy to grasp with one hand and does not require tight grasping, tight pinching, or twisting of the wrist to operate.

Status: The sliding doors have push-type mechanisms mounted below the 48” maximum height.

  • 4.13.11 Door Opening Force. The maximum force for pushing or pulling open a door is 5 pounds.

Status: The design specifications for these doors do not include opening force; it is therefore unknown whether the doors comply, particularly under the influence of ship’s motion.

3.1.2 Discussion
Review of the Flying Cloud ’s file indicates that no equivalency or special consideration was approved for the forward deckhouse doors. Interviews with Coast Guard personnel involved4 indicate that there are two keys to understanding the acceptance of these doors without coamings. The first is that the doors are always closed during operations, that is, once the boat leaves the dock.

The second, and most important, reason is the separate construction of the passenger cabin deck and of the watertight decks forming the upper bounds of the catamaran hulls. The structure connecting the two hulls, and supporting the superstructure of the cabin and pilot house, lies on top of the hulls’ upper watertight boundaries. These hulls, which provide the boat’s reserve buoyancy and stability, are strictly segregated from the overlying structure.

The clear reason for the acceptance of this design is that there is no opportunity for downflooding, even if water does enter the passenger cabin. Presuming that all manholes into the hulls’ main decks are closed as required (all spaces below are unmanned), there are simply no downflooding pathways for the water to follow. There is a potential concern that the free surface effect of water trapped in the cabin could also significantly degrade stability; the Flying Cloud file does not address that scenario, probably because of the drainage and closure arrangements. It is likely, furthermore, that the excellent transverse stability provided by the catamaran’s broad beam can sustain flooding of the passenger deck in the unlikely event that large amounts of water were to gain entry. The designers also took the extra precaution of providing an alternate drainage system both forward and aft of the doors.

3.2 Other Vessels
Research into other passenger vessel operators reveals that many T and K boats have weathertight doors without coamings, located on the main deck. These craft, in fact, are certificated to operate on “lakes, bays, and sounds” waters, and have “protected waters” language in their stability letters. They are, therefore, not subject to the explicit coaming requirements in Subchapters K and T. In the absence of specific knowledge of the designer’s intentions and the Coast Guard’s review, the likely scenario is that the Subchapter S provisions were not applied in these cases.

The New York Waterways ferries operation is a good example. Many of their boats are bow loaders in commuter service, similar to Flying Cloud and Lightning in this respect, designed to move large numbers of people on and off quickly. There are sliding double doors in the forward bulkheads of the deckhouses, with no coamings. These doors in the cases of their older, slower boats may even be left open during operations so that passengers can take the air on the bow.

Many of these boats have doors that serve to provide both embarkation access and deck access during operations. Some commuter ferries (e.g., Flying Cloud and Lightning) have separate doors for these purposes. In the latter case, embarkation and disembarkation are through doors only opened for that purpose, and which are always closed during operations.

Sayville Ferry Service reported operating vessels both with and without coamings, as well as another under construction without coamings, all in respect of the main deck weathertight doors. The COIs for these boats are for “lakes, bays and sounds” and the stability letters for “protected waters”, as for New York Waterways boats. The Subchapter T coaming regulation does not apply and there is no “equivalent” or “special consideration” called for. The likely scenario again is that the Subchapter S provisions were not applied in these cases.

The Alaska Marine Highway (AMH) is constructing two high speed vehicle and passenger ferries, the Fairweather and Chenega, at Derecktor Shipyards in Mamaroneck, New York. These catamarans will be 73 meters in length and will each carry 250 passengers and 35 large vehicles at a continuous-rating service speed of 35 knots. They are classed with Det Norske Veritas (Maltese Cross 1A1 HSLC) and have been accepted by the Coast Guard as fully compliant with international Safety of Life at Sea (SOLAS) and High Speed Craft (HSC) Codes.

Fairweather and Chenega will operate between Sitka and Juneau, Alaska, with the DnV “R3” service restriction. R3 means that the vessel must operate within 20 nautical miles of a safe harbor or anchorage in winter conditions and within 50 nautical miles of a safe harbor or anchorage in summer conditions. Project staff has not learned which area of operation is to appear on these vessels’ stability letters; R3 is the rough equivalent of “partially protected” waters.

The Coast Guard indicated to ATBCB that these craft have “minimal coamings”. Correspondence with AMH and Derecktor indicates that the doors in question were designed with 1–½” coamings, with grated ramps and deck drains. The weather deck served by these doors is well above the vessel’s main deck, at sufficient height that there is no chance of entry by waves on deck. An overhanging deck keeps rain and spray off the adjacent deck as well. Even in the most extreme listed damage condition, there is no chance of sea water entering through the doors in question.

Fairweather and Chenega do not require Coast Guard approval of equivalency or special consideration for the weathertight doors in question. The Subchapter K regulations state that coamings are required for doors “on the main deck of a flush decked vessel”. The main deck for Fairweather and Chenega is the vehicle deck, and the passenger accommodation decks are considerably higher, with negligible risk of ingress through the weather doors. These doors would also satisfy the Subchapter S coaming regulation as they are not in an “exposed” location.