Concept Report

ALASKA REGION RESEARCH VESSEL CONCEPT DESIGN REPORT

1.

INTRODUCTION

This concept design was completed under the auspices of a joint University of Alaska and Woods Hole Oceanographic Institution Oversight Committee. This committee consists of the following individuals: The University of Alaska Fairbanks Vera Alexander, Chair Robert Elsner Thomas Smith Terry Whitledge Thomas Weingartner Woods Hole Oceanographic Institution Richard Pittenger Robertson Dinsmore Joe Coburn An Advisory Committee consisting of the following individuals undertook a wider project review function: Mike Reeve, National Science Foundation E.R. Dolly Dieter, National Science Foundation Knut Aagaard, Polar Science Center, University of Washington Larry Atkinson, Center for Coastal Physical Oceanography, Old Dominion University John Christensen, Bigelow Laboratory George Hunt, Department of Ecology and Evolutionary Biology, University of California Irvine Suzanne Strom, Western Washington University James Meehan, National Marine Fisheries Service, NOAA Mike Prince, UNOLS The vessel described herein is a replacement vessel for the R/V Alpha Helix which was built in 1965 and is approaching the end of its useful life. This vessel was originally designed as a biological research vessel for Scripps Institution of Oceanography and was not intended for the rugged service demanded by year-round operations in the Bering Sea. It is a tribute to the vessel operators that they have been able to extend the useful life of this vessel well beyond a normal life expectancy. The replacement vessel is larger and more capable than the Alpha Helix as it must be for extended year-round operations in high latitudes. In addition to meeting the Scientific Mission Requirements (SMR) first developed in January 1999 by the interested science community, safety and operational considerations have been prime drivers of the design. Alaska Region Research Vessel Concept Design Report

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The design process that is being followed for this vessel seeks to optimize the interaction between the design team and the Design Oversight Committee. Concept design is the first step in a design cycle that will consist of: • • •

Concept Design Preliminary Design Contract Design

One of the primary goals of concept design is to ascertain whether all the desirable features and requirements, as outlined in the scientific mission requirements (SMR), can be attained within the anticipated principal dimensions. It is not the intent at the concept level to show every detail of arrangement. Overall considerations of weight and displacement, basic hull form concepts, speed and endurance, and, in the case of this vessel, limited ice operating capabilities are explored in the concept design cycle. The arrangement of blocks of spaces and their relationships with each other are also considered at this stage of design; e.g., is the block of labs conveniently arranged with regard to exterior and interior access, are the science storage spaces convenient to the labs and working deck, are the crew and scientist accommodation areas in generally convenient locations, etc. Details of specific space arrangements, fine-tuning of deck arrangements, and the like are normally considered in the next cycle: preliminary design. 2.

SUMMARY SPECIFICATIONS

In accordance with discussions at the 12 March 2001 review meeting and as a result of the seakeeping analysis (see Appendix F) we have arrived at the following principal dimensions for the concept design: Length, overall Length, design waterline Beam, maximum w/o reamer Beam, maximum w/ reamer Draft, at design waterline Depth, at amidships to main deck Displacement, at design waterline

226'-0" 200'-0" 48'-0" 52'-0" 18'-0" 29'-0" 2,800 LTSW

Note that length has increased to 226 feet versus the maximum 220 feet discussed at the design review meeting. It became necessary to lengthen the vessel in order to accommodate the estimated fuel load needed for the 45-day endurance requirement. The main capacities and capabilities of the vessel follow: Fuel capacity 148,000 gallons Ballast capacity 200,000 gallons Fresh water capacity 4,300 gallons Range 18,000 n.m. @ 12 knots Endurance – overall 45 days Provisions and human support consumable endurance 60 days Alaska Region Research Vessel Concept Design Report

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Level ice performance Variable scientific equipment capacity Trial speed Cruising speed Installed power

2.17 feet @ 2 knots 100 LT 14 knots 12 knots 5000 HP

The principal machinery for the current design concept consists of a raft-mounted diesel-electric power plant with twin azipod main propulsion thrusters and a bow thruster. The installed power is determined by the minimum American Bureau of Shipping (ABS) requirements for A1 Ice Class and will be refined during model tests. Science outfit is described in the Arrangements section below. 3.

SCIENTIFIC MISSION REQUIREMENTS

The concept design process has allowed considerable interaction with the Design Oversight Committee, which has resulted in continuous consideration of the consequences of complying with the SMR. As with any design cycle, some requirements have needed to be reconsidered in light of information gained during the design processes. Key modifications of the SMR requirements have come about primarily due to a realization of the size of vessel required to meet the combined requirements of ABS Ice Class, Endurance, and Canadian Arctic Pollution Prevention Regulations (CASPPR) requirement for double hull construction. As a consequence of these conflicting requirements, the Design Oversight Committee, after considerable discussion over the course of several review meetings, agreed to the following changes (see Appendix H for meeting minutes and project memorandums): •

Relaxing the dimensional constraints on draft (15 ft) and length (210 ft) (12 March review meeting) Given the desire to maintain the 45-day endurance requirement it was soon realized that the vessel principal dimensions anticipated by the original SMR were inconsistent with the desired mission profile. Additionally, the Committee decided after discussion with potential vessel users that the original constraint on draft was not critical and that a relaxation to 18 feet would not impair the ability to perform science operations. Also considered was the ability of the workboat carried on board to perform science operations in very shallow conditions. One positive aspect of the increase in draft is an increase in ice operability that results from deeper submergence of the propellers.

•

Elimination of the requirement to meet the International Council for the Exploration of the Sea (ICES) noise criterion (27 July review meeting) It became apparent early in the design cycle that meeting the ICES criterion with a twin screw, azimuthing propeller and an ice capable hull form would be very

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difficult. After consultation with our acoustic engineering subconsultants, Noise Control Engineering, and our propeller design consultant, Terry Brockett, it was determined that the criterion could not be met, even at a reduced speed. To meet the criterion the hull form and propulsion system must be optimized around the acoustic radiation limits. There are only a few research vessels in the world that meet this criterion and they are characterized by radically cut-away stern volume and single, large diameter, slow turning propellers driven by DC electric propulsion. •

Increasing the freeboard to 10 feet (12 March review meeting) The originally required freeboard of 4 to 6 feet was determined to be inappropriate given the relatively high sea states of the proposed operating area.

•

Setting the required variable science deadweight to 100 long tons (12 March review meeting) No requirement was given in the original SMR. The 100 LT was seen as an appropriate requirement given the possibility of expeditionary type science missions. “Fixed” science outfit such as: deck cranes: CTD and hydro winches; trawl winch, etc. are considered as part as of the vessel’s lightship weight.

•

Setting the trial speed at 14 knots and cruising speed of 12 knots (12 March review meeting) Considerable debate has been centered on the required maximum and cruising speeds. Operations in the Eastern Arctic have potentially long transit runs that make a high transit speed desirable.

•

Revising the speed requirement in level ice to 2 knots (12 March review meeting)

Section 16 of this report contains the full text of the scientific mission requirements as of 28 March 2001. Note that this revision to the scientific mission requirements does not reflect all of the changes accepted during the review meetings. 4.

ARRANGEMENTS

Section 15 of this report contains the concept arrangement drawings. The space matrix in Appendix A compares the concept arrangement with the scientific mission requirements. The main features for consideration are as follows: Decks/Access • •

The basic arrangement is a focsle deck vessel with main deck 10 feet above the waterline. A centerline trunk containing a stairwell and personnel/equipment elevator provides the main interior vertical access. Forward of this trunk are the main vertical ventilation trunk and the transducer centerboard well.

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•

•

Handicap access has been considered in the concept design. All main passageways are 48 inches wide allowing adequate clearances between handrails for a wheelchair. Elevator access to all public decks is provided, including the bridge deck where bird observation areas will be located. One science stateroom, on the 03 level will be arranged for handicap access, with larger washroom facility and other attributes. This stateroom is located directly adjacent to the elevator. The machinery casing and machinery space ventilation trunks are located at the aft end of the superstructure on the port side. This is typical for UNOLS research vessels as it provides for efficient arrangement of science spaces and good visibility along the starboard, working, side of the vessel.

Science Spaces • • • • • • • • •

A 48 inch wide central longitudinal passageway serves all labs. All science labs are located on the main deck. The wet lab has direct access to the Baltic room and the main deck through the Baltic room. Lab sizes are in accordance with the SMR. The science office is located on the main deck forward portside. The science freezers are located directly athwartship of the wet lab room, providing easy access for sample preservation. The climate control chamber is located on the 1st platform. Access is via elevator or stairway. A large science storeroom is located on the main deck forward starboard side, providing easy access to the labs. The science hold is located adjacent to an additional science stores area on the 1st platform aft. The hold is capable of stowing up to two containers if required.

Science Outfit • •

• •

Two main trawl winches (removable) are located on the after part of the main deck. Trawl blocks will be supported by removable gallows or by gallows attached to the A-frame. A trawl ramp, trawlway and A-frame with dimensions as specified for the NOAA FRV-40: 9 Trawl ramp

Width: Angle:

13 feet 37 degrees

9 Trawlway

Width: Length:

13 feet 48 feet

9 A-frame

Clear width: Clear height: Reach outboard: Reach inboard:

17 feet 20 feet 12 feet aft of transom 7 feet forward of top of ramp

A removable dual net reel is located on the 01 deck, aft. The main deep-water science winch (shown as a Markey traction winch) is located in the winch room on the 1st platform (below the main deck), starboard side. Two

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• • • •

•

storage drums are located forward of the winch. Wire is led via large diameter sheaves to a flag block above the main deck located on the aft corner of the hangar. The flag block will allow cable to be led either astern to the A-frame or over the starboard side. The CTD and hydro winches are located on the 1st platform just below the Baltic room. Wire from these winches will be led to the extendable boom in the overhead of the Baltic room or aft to the extendable hydro-boom in the hangar. A 20,000-pound capacity crane is shown on the port aft deck with operating cab at the 01 deck level. This crane is capable of reaching all parts of the aft main working deck and is also capable of loading/offloading 20-foot vans as required by the SMR. The smaller removable, 1-ton capacity, knuckle-boom crane will be located on the aft main deck, starboard side, and on the foredeck at the 01 level. The winch, crane and scientific control room is located on the aft end of the 01 deck, starboard side. The control room will provide excellent visibility of all areas of the aft main deck as well as the starboard side of the vessel. Visibility into the Baltic room is also provided. Two locations are provided for transducers in accordance with the SMR. Transducers are arranged forward on the centerboard and aft in a trunk.

Machinery Spaces • • • •

The main machinery space is located amidships on two levels: the 1st and 2nd platforms. The main machinery control room is located forward of the machinery space on the 1st platform level, port side. The main propulsor room is located aft at the 1st platform level. Currently an azipod drive configuration is shown. A thruster room is located forward at the 2nd platform level. The current arrangement shows an Elliot White-Gill type thruster, although a conventional tunnel thruster could also be configured in the available space.

Accommodations • •

5.

All accommodations are located above the main deck with the majority of the crew and science accommodations in double cabins located on the 01 deck. Captain, chief engineer, mates, first and second engineer, chief scientist and handicap science accommodations single cabins are located on the 02 deck.

HULL FORM

The challenge presented to the design team in regard to hull form was to arrive at the appropriate compromise between open water performance and ice operability. In the case of this vessel it is anticipated that a majority of mission time will be in open water. However, the vessel must also be able to function efficiently in limited ice conditions so that year-round operations can be achieved in the Bering Sea and limited missions to the Chukchi and Beaufort can be undertaken.

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The Glosten Associates retained Dr. Arno Keinonen of AKAC, Inc. as a hull form and propulsion consultant on ice operations. Dr. Keinonen has extensive experience with modern ice-capable vessel design and performance evaluation. It should be emphasized that the hull form currently proposed for this vessel has moderate ice-breaking features appropriate to the limited nature of the ice mission. Additionally the incorporation of features such as azimuthing propellers, moderate reamers and ice wedge, have benefits in both ice operations and open water operations. The azimuthing propellers provide superior maneuverability and station-keeping in open water while contributing significantly to the vessel’s ability to navigate in ice. Features such as the reamers and ice wedge, while increasing the vessel’s open water resistance, provide additional damping which will contribute to the vessel’s sea-keeping ability. The main hull form features desirable for open-water performance and ice capability are listed below as main bullet items. Sub-bullets describe the reasoning behind the features and discuss actual hull parameters achieved in the present design where deviations occur. Reports by AKAC Inc., our icebreaking subconsultant, can be found in Appendix C. •

Moderate icebreaking buttock angles of 23 degrees forward and 25 degrees aft. ➢ Stern buttock angle of 28 degrees reflects a design compromise to minimize overall vessel length and still maintain thruster coverage with the hull. A slight reduction in backing performance is expected. ➢ The moderate angles tend to push thicker ice to the side rather than under the vessel giving a high percentage of operation in the ice margin where the vessel is likely to experience broken floes thicker than the nominal icebreaking capability of the vessel. ➢ Other benefits include lower probability of getting stuck in ice, improved tracking in open water and moderated slamming. ➢ Consequence: 10% reduction in level ice performance relative to hull forms with shallower angles.

•

Propulsion plateau angled 5 degrees transversely and 3 degrees longitudinally. ➢ Transverse angle reduced to 3 degrees in line with azipod manufacturer’s recommendations. ➢ Longitudinal cant improves inflow into propeller and permits steeper buttock flow from baseline. ➢ Icebreaking and ice removal using the propulsion unit wake for over-the-side work. ➢ Clears ice from wake for over-the-transom work.

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•

Rounded stern lines with stopper. ➢ Improved backing performance. ➢ Vertical appendage above the propulsion plateau serving to stop the vessel when backing into thick ice.

•

Propulsion units located at minimum separation distance recommended by manufacturer to maximize protection from ice.

•

Propeller tip clearance equals level ice-thickness plus snow margin. ➢ Achieved propeller tip clearance is approximately 2'-5", whereas the estimated level ice performance is about 2'-9". The tip clearance assumes a 9'-6" diameter propeller and could be increased if a smaller diameter is feasible.

•

Skeg for open water roll damping and docking.

•

Ice wedge. ➢ Pushes ice sheets to side of vessel. The minimum length of the frame from the waterline to the forward end of the wedge is equal to the half-breadth. ➢ Consequence: 10% increase in open water resistance. ➢ Some portion of the forward edge of the ice wedge should be vertical to serve as a bow stopper. ➢ Provides location for bow thruster.

•

Reamer each side (two feet) or midship flare 10 degrees. Reamer design has advanced considerably since the early days of Beaufort Sea oil exploration/support. Their effectiveness in ice continues to improve and their detrimental effect on open water resistance has been reduced. ➢ Reduces hull pressure when beset in ice. ➢ Prevents wedging hull into thick ice by ramming. ➢ Allows vessel to turn efficiently in ice. ➢ Consequence of reamer: 10% increase in open water resistance.

Three candidate hull forms were developed in the course of this concept design using the guidance above. The lines plan of the initial hull form (ARRV_1) is presented in the figure below to illustrate some of the hull form features described above. The lines drawing for the current hull form (ARRV_3) is included with the other concept drawings in Section 15 of this report. Several changes to the current lines recommended by AKAC Inc. will be incorporated in the preliminary design phase: •

The reamers should not be vertical as shown, but should have a minimum slope of seven degrees.

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•

The ice wedge is too wide for optimum ice resistance and open water performance. The depth of the ice wedge could also be reduced by half; however, it would be less effective at splitting ice floes.

•

The fore and aft chines of the reamer should be rounded off to reduce open water resistance.

•

The propeller tip clearance should be increased to about 3.5 feet in order to avoid ice/ propeller inaction and cavitation associated with presence of ice.

•

A softening piece should be added to the ice wedge so that the leading edge is not vertical near the hull.

Propulsion Plateau

Stopper

Reamers

Ice Wedge

Figure 1 Ice Features – ARRV_1

6.

RESISTANCE AND PROPULSION

Speed and power estimates have been performed for the current hull form and are shown in the figures below. Included in the following discussion are the resistance estimates for the original (ARRV_1) hull form, the alternate (ARRV_2) hull, and the current hull form (ARRV_3) with and without reamers. The ARRV_2 and ARRV_3 represent open water based, ice-capable hull forms, which fall within the applicable regression parameters of the Holtrop statistical resistance prediction method. Therefore, resistance estimates for the ARRV_2 and ARRV_3 use the Holtrop method as implemented in the NavCad software.

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On the other hand, the ARRV_1 hull form reflects contemporary icebreaking hulls and presents a challenge for accurate resistance prediction. Two data points exist that can be used to assess the resistance for the ARRV_1: the model tests for the ARV (Arctic Research Vessel) and the model tests for the GLIB (Great Lakes Icebreaker). The ARRV_1 utilizes most of the icebreaking hull form features found on the ARV; however, the ARRV_1 is a much shallower draft concept. The GLIB closely resembles the ARRV_1 in principal dimensions. Correlation of the model tests to the ARRV_1 hull results in resistance estimates much higher than the Holtrop method prediction for the ARRV_1, as expected. See Figure 2. This comparison provides a rough approximation of the resistance penalty for icebreaking features. The current best estimate for the resistance of the ARRV_1 candidate hull form is based on the GLIB model tests with reamers added. Note that the ARRV_1 does not make the 14 knot design speed with an installed power of 3730 kW (5000 HP). AR RV_1 P o w e r Es tim a te s (Assu m ed over a ll pr opu lsive coefficien t = 0.5) 7000 GLIB In st a lled P ower = 6260 kW 6000

Brake Power, PB [kW]

5000

4000

ARRV In st a lled P ower = 3730 kW

ARRV_1 (ARV) ARRV_1 (GLIB w/ r ea m er s) ARRV_1 (GLIB)

3000

ARRV_1 (H olt r op)

2000

1000

0 0

2

4

6

8

10

12

14

16

S p e e d [k ts ]

Figure 2 Original Hull Form (ARRV_1) Power Estimates Contemporary icebreakers utilize reamers to reduce ice resistance, improve maneuverability in ice, and direct ice away from the propellers. The open water resistance penalty applied to the hull variants for the addition of reamers and the ice wedge is 20 percent. Figure 3 summarizes the predicted power required for the various hull forms. The results presented for the ARRV_1 and ARRV_2 assume an overall propulsive coefficient of 0.5 applied to total resistance. The results for the ARRV_3 represent a later stage in design progression and consist of a more rigorous propulsion estimate. An overall propulsive coefficient of about 0.60 was achieved using wake fraction, thrust deduction Alaska Region Research Vessel Concept Design Report

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and relative rotative efficiency estimates based on Holtrop. Mechanical efficiencies of 99 percent and 91 percent were assumed for the shafting and diesel-electric propulsion system, respectively. One cautionary note: the power estimates are based on the methods of Holtrop, which may not be conservative for the hull form with reamers. The resistance penalty for the reamers will need further evaluation during model testing.

Figure 3 P ow er vs. Speed Ca n d id a te Hu ll F o rm Co m p a ris o n 6000

5000

In st a lled P ower +15% = 4290 kW

Brake Power, PB [kW]

4000

In st a lled P ower = 3730 kW ARRV_1 ARRV_2

3000

ARRV_3 ARRV_3 w/ Rea m er s 2000

1000

0 0

2

4

6

8

10

12

14

16

S p e e d [k ts ]

Speed and Power Estimates Note that at current estimates of installed power (5,000 BHP or 3,750 kW) a maximum calm water speed of approximately 15.5 knots is estimated for the current hull without reamers. This drops to about 14.5 knots with the reamer. The speed and power estimates for the ARRV are comparable to similar research vessels and icebreakers as shown in Appendix B. Additional power, on the order of 15%, will benefit the ice performance of this vessel. The inevitable propeller-ice interaction that will occasionally take place will require the extra horsepower from the propulsors so that loss of propulsive efficiency does not occur as soon as ice enters the propellers. This added horsepower would also benefit open water speed. The availability of propulsors has been investigated to the extent possible in this phase of the design. Our contacts with the three producers of podded propulsion units has revealed only one manufacturer willing to build units in our size range. This Alaska Region Research Vessel Concept Design Report

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manufacturer is ABB, who built the units on the Finnish icebreaker Botnica. However, our contacts with ABB have been less than satisfactory. They eventually responded to repeated requests for basic information, e.g., unit size, weights and cost. See Appendix G for their delayed response. Additionally, ABB does not seem receptive to producing a unit that has any special noise considerations and they have not shown a willingness to produce any radiated noise information on their own. Although the communications have not been good, it was felt that the technology has enough merit that we should, at least for the time being, proceed with the azipod arrangement in the preliminary design phase. Azimuthing thrusters, either azipods or Z-drives, have been demonstrated to greatly improve ice operability and safety. They enhance available thrust astern and they enable breaking and clearing of ice with the propeller wash. They also greatly improve maneuvering in ice and open water. The option of Z-drives will also be kept open. The impact to hull form between these two options is not significant. 7.

SEAKEEPING

The following table summarizes a variety of seakeeping criteria in the literature and identifies the criteria selected to use for the ARRV seakeeping evaluation. Table 1 Seakeeping Criteria Proposed Seakeeping Criteria for Alaska Region Research Vessel (to be met at Sea State 5, wave height 8-13 feet) Description Criteria Comments Reference [RMS values] Vertical Acceleration Work of more demanding type 0.10g Long term tolerable for crew Payne 1976 Heavy manual work 0.15g Limits in fishing vessels Payne 1976 Maximum vertical acceleration 0.20g 8 ft Hs from 0-11 knot & 13 NOAA FRV-40 ft Hs from 0-4 knots Main Lab 0.10g Stern trawler Nordforsk SNAME PNA 1.40g Trawler Aertssen 1968,1972 MERV, SMP data 0.165g* MP - centerline – main deck MT Paper 1987 The Criteria to Use: 0.20g SMR Roll Light manual work Demanding work Maximum RMS roll angle

4.0 3.0 4.0

Main lab SNAME PNA MERV, SMP data The Criteria to Use:

3.0 4.0 9.47* 3.0

Alaska Region Research Vessel Concept Design Report

Personnel effectiveness Personnel effectiveness 8 ft Hs from 0-11 knot & 13 ft Hs from 0-4 knots Stern trawler Naval Monohull

12

Comstock 1980 Hosada 1985 NOAA FRV-40 Nordforsk Comstock 1980 MT Paper 1987 Hosada 1985,

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Proposed Seakeeping Criteria for Alaska Region Research Vessel (to be met at Sea State 5, wave height 8-13 feet) Description Criteria Comments Reference [RMS values] Nordforsk Pitch Light manual work Demanding work Maximum RMS pitch angle

2.0 1.5 2.3

SNAME PNA MERV, SMP data The Criteria to Use:

1.5 3.68* 1.5

Horizontal Acceleration Passenger on a ferry

0.025g

Navy crew

0.050g

Standing passenger

0.07g*

Maximum RMS lateral acceleration Main Lab SNAME PNA MERV, SMP data The Criteria to Use: Note: * = Maximum value

0.10g 0.05g 0.10g 0.056g* 0.10g

Personnel effectiveness Personnel effectiveness 8 ft Hs from 0-11 knot & 13 ft Hs from 0-4 knots Naval Monohull

1-2 Hz frequency. General public Non-passenger and navy ship 99% will keep balance without need of holding 8 ft Hs from 0-11 knot & 13 ft Hs from 0-4 knots Stern Trawler Naval Monohull

Hosada 1985 Hosada 1985 NOAA FRV-40 Comstock 1980 MT Paper 1987 Hosada 1985, Comstock

ISO 2631/1

Hoberock 1976 NOAA FRV-40 Nordforsk Comstock 1980 MT Paper 1987 SMR

Given the importance of seakeeping in SMR, special consideration was given to the hull proportions with regard to developing good seakeeping qualities. Previous design and model test work on the 1988 Medium-Endurance Research Vessel (MERV) and the 1992 Arctic Research Vessel (ARV) indicated that a wide shallow hull, i.e. a high beam-todraft ratio, results in good seakeeping qualities. Accordingly, the initial design efforts selected hull proportions with a high B/T ratio. ARRV_1 had a beam of 55 feet and a draft of 15 feet, resulting in a beam-to-draft ratio of 3.68. A second hull variant was developed with more conventional proportions in an effort to reduce the open water resistance and to explore an alternative design space. ARRV_2 had a beam of 43 feet and a draft of 18.75 feet, resulting in a beam-to-draft ratio of 2.29. The anticipated advantages of the high beam-to-draft ratio hull form were not realized in the initial seakeeping studies. While ARRV_1 did show some advantage over ARRV_2 in terms of vertical accelerations at headings near head seas, the RMS vessel coordinate lateral acceleration in the main laboratory for ARRV_1 in high sea state 5 is 0.238 g which compares with 0.148 g for ARRV_2. Consequently, further investigations were undertaken to determine if achievable design changes could improve performance

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and to better understand the motion responses that were being predicted. These further investigations included: •

Investigating a broad range of variations of vertical center-of-gravity and physical roll gyradius for ARRV_1 and ARRV_2 hull forms.

•

Investigating the lateral acceleration performance of a systematic seakeeping series characterized by constant displacement and beam-to-draft ratios varying from 2.0 to 5.0.

•

Expanding the analytical seakeeping models to incorporate U-tube anti-roll tanks and investigating the benefits of such tanks for ARRV_1 and ARRV_2.

For an in-depth discussion of the seakeeping results, see Appendix F – Seakeeping Studies and Roll Investigations. Based on the results of the B/T series investigations, the widest hull form consistent with operating near the stability limit (relatively low GM) results in the lowest lateral acceleration at all locations above the waterline. Accordingly, the ARRV proportions were selected toward this optimization. The current design includes a 70 LT allowance for installation of an anti-roll tank. Based on Figure 30 in Appendix F, a reduction in lateral acceleration on the order of 20% can be expected from an anti-roll tank. The current hull form shows much improved seakeeping behavior over the original hull form and compares very favorably with the R/V Knorr. One very important measure of seakeeping behavior is the magnitude of lateral (sway) acceleration in a given sea state. This characteristic influences vessel operability in terms of the effectiveness and comfort of personnel. Figure 4 compares values of sway acceleration versus height above the waterline for: the original hull form, ARRV1; the alternative hull form, ARRV2; and the current hull form, designated in the figure as ARRV3. Note that values are given for each vessel with and without anti-roll tank; and, in the case of the current design (ARRV3), values with bilge keels are shown – although at this time we are not considering bilge keels due to their vulnerability in ice. Further design cycles should include consideration of “ice-friendly” bilge keels.

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RMS Sway Acceleration in Vessel Coordinates 100

80

Elevation, Rz (feet)

60

40

20

0 0

1

2

3

4

5

6

7

8

9

10

ARRV1 With 250 L.T. Anti-Roll Tank ARRV1 Without Anti-Roll Tank ARRV2 With 235 L.T. Anti-Roll Tank ARRV2 Without Anti-Roll Tank ARRV3 With 10 L.T. Anti-Roll Tank ARRV3 Without Anti-Roll Tank ARRV3 With Bilge Keels

-20

-40

-60 File 00100

RMS Sway Acceleration in Vessel Coordinates (ft/sec^2)

3-May-01

FIGURE 4 Lateral Acceleration in Vessel Coordinates as a Function of Elevation We have also developed polar plots showing the behavior of the vessel in upper Sea State 5, the maximum sea state in which science operations are to take place in accordance with the SMR. Two characteristics of particular interest, in addition to the lateral acceleration characteristics described above, are the vertical acceleration and roll angle. These are shown below superimposed on estimated values for the R/V Knorr for comparison purposes. Vertical acceleration affects operability due to its influence on personnel efficiency and seasickness. Roll angle does not affect personnel effectiveness as much as acceleration characteristics, but it influences over-side operations. The following figures compare the predicted seakeeping performance of the ARRV and R/V Knorr at 9 knots with the seakeeping criteria identified in this section. Note that while the criteria are difficult to meet in high Sea State 5 (13.2 foot significant wave height), the ARRV compares favorably to the Knorr in terms of lateral acceleration and roll angle. The ARRV exhibits slightly more pitch angle than the Knorr, as expected due to the shorter length. The only seakeeping criterion that is met by both the ARRV and the Knorr is vertical acceleration.

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RMS Ve rtic al Ac c e le ra tio n (g %) vs . Ve s s e l He a d in g Ma in Deck, Cen ter lin e, Midsh ips (9 knot s, H s=13.12 ft , Wor st P er iod) 0 345

20

15

18

330

30

16 315

45

14 12

300

60

10 8 6

285

75

4 2 270

ARRV

0

90

Kn or r Cr it er ion

255

105

240

120

225

135 150

210 195

165 180

Figure 5 RMS Vertical Acceleration RMS Ro ll An g le (d e gre e s ) v s . Ve s s e l He a d in g (9 knot s, H s=13.12 ft , Wor st P er iod) 0 345

10

15

9

330

30

8 315

45

7 6

300

60

5 4 3

285

75

2 1 270

ARRV

0

90

Kn or r Cr it er ia

255

105

240

120

225

135 210

150 195

165 180

Figure 6 RMS Roll Angle Alaska Region Research Vessel Concept Design Report

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RMS P itc h An gle (d e g re e s ) v s . Ve s s e l He ad in g (9 knot s, H s=13.12 ft , Wor st P er iod) 0 345 330

3.0

15 30

2.5

315

45 2.0

300

60

1.5 1.0

285

75 0.5 ARRV

270

0.0

90

Kn or r Cr it er ia

255

105

240

120

225

135 210

150 195

165 180

Figure 7 RMS Pitch Angle RMS La te ra l Ac c e le rati on (g %) vs . Ve s s e l He a d in g Ma in Deck, Cen ter lin e, Midsh ips (9 knot s, H s=13.12 ft , Wor st P er iod) 0

345

20

15

18

330

30

16 315

45

14 12

300

60

10 8 6

285

75

4 2 270

ARRV

0

90

Kn or r Cr it er ia

255

105

240

120

225

135 210

150 195

165 180

Figure 8 RMS Lateral Acceleration Alaska Region Research Vessel Concept Design Report

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R MS Ve rt ic al Ac c e le ra tio n (g %) vs . Ve s s e l He a d in g Ma in Deck, Cen ter lin e, Tr a n som (9 knot s, H s=13.12 ft , Wor st P er iod) 0 345

20

15

18

330

30

16 315

45

14 12

300

60

10 8 6

285

75

4 2

ARRV

0

270

90

Kn orr Cr it er ia

255

105

240

120

225

135 210

150 195

165 180

Figure 9 RMS Vertical Acceleration at Transom

8.

RANGE AND ENDURANCE

Several mission profiles were developed based upon the scientific mission requirements (SMR) for the design of this vessel, guidance from the review meeting on 3/12/01, and the NOAA Fisheries Research Vessel (FRV) Statement of Requirements. The SMR for this vessel requires a 45-day endurance with 20 to 25 percent of ship time in ice. Because we assume that ice operations absorb 90 percent of full power, the mission profiles including ice operations tend to drive the design fuel requirements. The tables below summarize the mission profiles evaluated. Note that the NOAA mission profiles were scaled from a 40-day endurance to 45 days.

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Table 2 Ice Cruise Mission Profiles ICE CRUISE TYPE Mission Element

168 hours at 12 knots 240 hours at 90% power

Meeting Example – A 240 hours at 12 knots 240 hours at 90% power

Meeting Example- B 240 hours at 12 knots 240 hours at 90% power

On Station Ice-free

672 hours at 6.0 knots

not applicable

300 hours at 6.0 knots

Between Stations

not applicable

600 hours at 6.0 knots

300 hours at 12 knots

Total Hours

1080

1080

1080

Transit Ice-free Ice

Typical

Table 3 Scaled NOAA FRV Mission Profiles NOAA CRUISE TYPE Mission Element Transit

Marine Mammal Observation not applicable

Bottom Trawl

MOCNESS Survey

Hydroacoustic/ Pelagic Trawl

135 hours at 13.5 knots not applicable

458 hours at 13.5 knots 588 hours Towing 17.8 kN Resistance at 1.5 knots not applicable

90 hours at 13.5 knots 585 hours at 11.0 knots

On Station

1035 hours at 10.0 knots

Between Stations

not applicable

405 hours at 12.0 knots

Drift/Anchor

45 hours at 0 knots

not applicable

not applicable

not applicable

Trawling with 160 kN Resistance Net Ocean Research

not applicable

405 hours at 4.0 knots

not applicable

315 hours at 5.0 knots

not applicable

135 hours at 0 knots

34 hours at 0 knots

45 hours at 0 knots

Total Hours

1080

1080

1080

1080

45 hours at 12.0 knots

Table 4 summarizes the required fuel capacities and the associated ranges for the mission profiles outlined above. The fuel capacities are calculated assuming calm conditions, a 2% tail pipe factor, a 15% reserve fuel allowance and a specific fuel Alaska Region Research Vessel Concept Design Report

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consumption of 0.36 pounds per horsepower-hour. All results include a 45-day hotel load of 790 HP. Stationkeeping power includes 540 HP for the bow thruster and associated auxiliaries. The table presents the required capacities for the ARRV with reamers and an ice wedge. The total fuel capacity required for the ARRV without the icebreaking features is not appreciably lower, because the low-speed, full-power ice mission elements drive the fuel capacity. These estimates will be refined as the design progresses and ice resistance estimates become available. Table 4 Fuel Capacity and Range Mission Profiles Summary – ARRV w/ reamers & ice wedge Cruise Type Fuel Capacity Range at Full Fuel @ 98% 12 knots Power consumption [gallons] [n.m.] [gal/day] Days Ice Cruises Meeting Example 3/12/01 - A 149334 18490 21 2836 166694 20640 24 3166 Meeting Example 3/12/01 – B* Typical 145328 17994 21 2760 NOAA Cruises Marine Mammal Observation 97851 12116 14 1859 Bottom Trawl 132686 16429 19 2520 MOCNESS Survey 146894 18188 21 2790 Hydroacoustic / Pelagic Trawl 124396 15403 18 2363 Current Design** 148320 18300 21 Fuel consumption at full power 5952 Notes: *Not achievable at current design draft. **Limited by displacement at the 18'-0" draft. Fuel consumption values assume a specific fuel consumption of 0.36 lbs. / HP-hr

An additional fuel capacity of approximately 20,000 gallons is required in order to meet the SMR requirement for a 60-day hotel load. This fuel load corresponds to a draft increase of about 3 inches. An additional draft increase of about 4 inches is required in order to carry enough fuel for Mission Profile B. 9.

STABILITY

Subdivision A one-compartment flooding standard is required by 46 CFR 173.075 and 46 CFR 171.070. Canadian Arctic Shipping Pollution Prevention Regulations (CASPPR) require that all vessels, other than vessels operated solely as icebreakers, meet a twocompartment standard of flooding. In addition to the subdivision requirement, all tanks containing pollutants or waste are held a minimum of 2.5 feet inside of the hull per the requirements of CASPPR. Although we are not strictly required to conform to Alaska Region Research Vessel Concept Design Report

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this regulation since this requirement is for “class” type ice-breaking vessels, it seems a reasonable requirement in light of the biological sensitivity of some operating areas. The one-compartment damage stability requirements will be met by the arrangement of several transverse watertight bulkheads below the main deck. Access through some of these bulkheads will be provided by automatically closing watertight doors actuated from the bridge. The extent of damage for the two-compartment standard of flooding in the CASPPR regulations allows credit for the double bottom and double side. Therefore, the current arrangement should meet two-compartment flooding in accordance with CASPPR. Stability The fairly full waterplane of the vessel will provide adequate intact stability. We expect that any or all of the required 100 tons of variable science deadweight can be carried on the main deck or the 01 deck if required. 10. NOISE An acoustics subconsultant, Noise Control Engineering, Inc. (NCE), was tasked with investigating the feasibility of achieving the ICES radiated underwater noise standard for this vessel. Appendix D contains NCE’s full report. The main points are summarized here and discussed in the context of design impact. In summary, NCE states that: “If the ICES radiated noise goal is specified, the High Latitude Research Vessel would need to be as quiet as the quietest research vessels afloat today. Extensive noise and vibration controls will be required. The most critical single component will be the design of a quiet propulsor. The hull form (wake) and propeller speed and diameter will determine the success of the propeller design.” A quiet ship design consists of two main components: a cavitation-free propeller and a propulsion plant with extensive noise control measures. Each of these components is addressed in turn below. As discussed in the propeller section below, achieving a cavitation-free propeller at 11 knots is simply not feasible within the current design constraints. Note that a single 14 foot diameter propeller was required on the NOAA FRV to achieve a cavitation-free propeller at 11 knots. Accommodating a 6-foot increase in diameter would require an increase in hull depth and a drastic change in hull form. The general character of the NOAA FRV hull form with its extremely fine stern is not suitable for ice operations. The propellers need to be located deeper in the water to avoid ice debris and need greater tip clearance to pass ice chunks. Changing to a single screw configuration abandons the maneuvering and icebreaking advantages of azimuthing twin screw drives. NCE believes that a diesel-electric plant represents the only viable approach to achieving the ICES underwater noise requirements. Raft mounting of the diesel generators will be required to minimize propulsion engine hull radiated noise. Raft Alaska Region Research Vessel Concept Design Report

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mounting and the other noise control measures enumerated in the NCE report carry significant weight and cost penalties. The current design incorporated azipod units for a perceived acoustic benefit over standard Z-drive units. Azipod units are advantageous in providing good inflow to the propeller, but they place the propulsion motor in the water where sound attenuation is difficult. NCE does not believe azipods units provide an acoustic advantage over standard fixed pitch or Z-drive systems. NCE suggests two different and complementary approaches to relaxing the ICES requirements. 1) Limit the frequency range for applying the ICES requirements to between 10 Hz and 50 kHz. There are inherent difficulties in controlling and/or measuring underwater sound outside this range. 2) Accept a lower ship speed. Lower ship speeds have lower horsepower requirements, making isolation easier. NCE notes that an azipod system may not benefit, since motor noise could actually increase at lower speeds. The picture that NCE paints for meeting the ICES standard is bleak at best. Many of the design requirements for quiet operation and icebreaking are mutually exclusive. However, meeting the noise requirement at a lower speed may be possible, if it has benefits to the science community. The cost and benefit of attempting to meet a noise standard should be carefully weighed before proceeding with the next design phase. Some nominal noise control measures, such as incorporating isolation mounted diesel generators and developing a cavitation free propeller, will be included, regardless of whether the vessel meets the published ICES noise standard at any speed. 11. PROPELLER DESIGN A propeller design expert, Dr. Terry Brockett, who has many years of experience in designing quiet propellers, was also tasked with investigating the feasibility of achieving the ICES noise standard for this vessel. Initial estimates indicate that a propeller design of similar character to the NOAA-FRV propeller is feasible. The hydrodynamic design point for the propeller will be 11 knots in order to minimize noise levels due to cavitation. Degradation in propulsive efficiency can be expected at speeds off the design point. The radiated propeller noise is governed largely by cavitation. Noise reductions are obtained by delaying tip vortex cavitation inception. Preliminary calculations indicate that designing the ARRV propellers with vortex inception at 11 knots will result in an unacceptable propulsive efficiency of about 50 percent. Vortex inception occurs at 9 to 10 knots for propeller designs with reasonable propulsive efficiency in the 60 to 65 percent range. A five-bladed propeller is recommended for advantages in efficiency, cavitation, and possible blade-rate vibration. An 8.2 foot diameter was selected in order to provide adequate tip clearance for operations in ice. The table below compares results for five-bladed propellers with a blade area ratio of 0.65 operating at different speeds. Alaska Region Research Vessel Concept Design Report

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Table 5 Propeller Noise Estimates RPM

Propulsive Coefficient

200 180 160

0.60 0.64 0.67

Vortex Inception Speed [knots] 10 9 8

Radiated Noise Estimates @ 11 knots 0.1 kHz 126 125 122

1 kHz 116 115 113

10 kHz 104 100 96

40 kHz 89 85 81

Figure 10 compares the propeller noise estimates at 8, 9 and 10 knots with the ICES criterion. Note that the estimated propeller noise levels are fairly close to the ICES criterion. We expect that the addition of machinery noise would drive the estimates well beyond it.

Estimated Propeller Noise versus ICES Radiated Noise Limits

SPL, dB re 1 micro-Pa @ 1 meter

160

140

ICES limit

120

200 RPM, Vortex inception @ 10 kts 100

180 RPM, Vortex Inception @ 9 kts 160 RPM, Vortex inception @ 8 kts

80

60 1

10

100

1,000

10,000

100,000

Frequency, Hertz

Figure 10 Propeller Noise Further investigation into the effect of propeller speed on propulsion motor size will be required as the design progresses, to determine whether the propellers above are compatible with the azipod concept.

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12. MANNING STUDY The regulatory requirements applicable to manning the research vessel were reviewed with regard to the ARRV. The ARRV is expected to operate with a reduced crew complement of 17, assuming that the vessel operates with a periodically unattended machinery plant and obtains an ACCU designation. Note that during the initial certification and trial period the required crew complement increases to 20. Table 6 summarizes the relevant regulations and interpretations. Common research vessel practice indicates the need for an electrician to serve as a communication/electronics technician. The electrician could replace the oiler or the mess assistant to maintain the minimum crew size, since these positions are not specifically required. Alternatively, electricians can serve as part of the science complement. Table 6 Manning Requirements

MANNING STUDY FOR ARRV POSITION

ARRV ALPHA REGULATORY REFERENCES INTERPRETATIONS / ASSUMPTIONS QUANTITY HELIX MIN1 MAX2 QUANTITY Master 1 1 1 46 CFR 15.805(a)(1) & 815(a) 'Every self-propelled, seagoing documented vessel of 200 gross tons and over.' Mate 3 3 1 46 CFR 15.810(b)(1) & 815(a) 'Vessels of 1000 gross tons or more - three licensed mates.' Able Seaman 4 4 4 46 CFR 15.840 and Marine 65% of deck crew must be AB's. Each Safety Manual Vol. 3, Chapter watch will have helmsman and lookout 23.D.1 based on mission requirements. Ordinary 2 2 0 46 CFR 12.25-1 and Marine 65% of deck crew must be AB's, therefore Seaman Safety Manual Vol. 3, Chapter remaining compliment can be Ordinary 23.D.1 Seamen Chief 1 1 1 46 CFR 15.820(a)(1) 'Seagoing or Great Lakes vessels of 200 Engineer gross tons and over.' Assistant 2 3 0 46 CFR 15.825 Licensed Assistant Engineer(s) required; Engineer OCMI determines quantity based on level of automation. (over 200 GT) Oiler (QMED) 1 1 1 Marine Safety Manual Vol. 3, Billet not specifically required by CFR. No Chapter 23.E.4 unlicensed watchstander required in engine room with "deadman" alarm. Wiper 0 1 0 Marine Safety Manual Vol. 3, Billet not specifically required by CFR. No Chapter 23.E.4 unlicensed watchstander required in engine room with "deadman" alarm. Chief 1 1 0 46 CFR 12.25-1 & -2 Billet not specifically required by CFR. Steward Must be food handler endorsed. Cook 1 2 1 46 CFR 12.25-1 & -2 Billet not specifically required by CFR. Must be food handler endorsed. Mess 1 1 0 46 CFR 12.25-1 & -2 Billet not specifically required by CFR. Must be food handler endorsed. Assistant Total Crew 17 20 9 Scientist 243 24 12 1. Minimum crew size based on minimum requirements by regulations and emergency squad capabilities 2. Maximum crew size based on predictions of maintenance and extended mission requirements 3. Two electrician/techs will be part of scientific compliment and will have lifeboatman/MMD certification.

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13. COST ESTIMATES A total acquisition cost of $57 million is estimated for the ARRV project. The daily rate of the ARRV is estimated to be $15,200 per day. Appendix E discusses in detail the basis of the acquisition cost and daily rate estimates. 14. DESIGN TRADE-OFF STUDIES Several design decisions were made as the concept design phase drew to a close. We list the design trade-offs below and attempt to provide some discussion to document the decision making process. Note that in most cases qualitative engineering judgment and experience was relied upon rather than quantitative analysis. •

ICES noise versus ice performance

A large part of the discussion in this report focuses on the ICES noise criterion, since meeting it was a major consideration during the concept design. Satisfying the ICES noise criterion and improving icebreaking performance push the hull and propulsion system designs in different directions. At this point we believe the two design goals to be incompatible. Abandoning azimuthing propulsion for the sake of noise directly would have reduced the ice capability of the vessel. Azimuthing propulsion increases maneuverability in the ice. In addition, the azimuthing units can be oriented to clear the channel of ice rubble or break ice directly with the thrust. Arno Keinonen comments that vessels with azimuthing drives are independently operable in perhaps 30 percent thicker ice than their conventionally propelled counterparts with the same hull and power. The ability to meet the ICES noise criterion with this vessel was discussed at the 27 July review meeting. Our acoustic sub-consultants, NCE, believe that it is essentially unachievable with azimuthing drives due to AC motor noise in the case of azipods and gear noise in the case of Z-drives. In order to meet the ICES criterion the vessel would need to be amongst the quietest vessels in the world and the hull and propulsor design would need to be completely optimized to meet this criterion. This is not compatible with the stated multi-purpose mission of this vessel, particularly the ice operations. There was agreement to delete the requirement to meet the ICES noise criterion. The vessel will still be designed to be as quiet as is practical. This means we will continue with the assumption that all machinery will be acoustically isolated and diesel electric propulsion will be used. Propellers will be of a “quiet” design to the extent possible given their required ice class. •

Low open water resistance versus ice capability

As a rough approximation, the ice wedge and reamers each carry a 10% open water resistance penalty. The resistance combined with the required endurance drives the size of the vessel. So the design trade-off is not just open water resistance versus ice capability, but capital cost and operating cost versus ice operability.

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The contribution of the ice wedge and reamers to ice operability is not easily quantifiable. Experience with modern icebreakers shows that these hull form features improve ice operability significantly by reducing propeller-ice interaction and by clearing the channel behind the vessel. These features also reduce the probability of the vessel becoming beset in ice. Arno Keinonen estimates that a vessel with reamers and ice wedge would be independently operable in 10% thicker ice than a vessel without these hull features. After much discussion of ice capability at the 27 July review meeting, it was agreed that the existing hull form, with modest reamers, wedge and azimuthing drives, should be retained and refined as we proceed to preliminary design and model testing. Additional power, on the order of 10-15%, will benefit the ice performance and increase the open water transit speed of this vessel. The impacts of adding power will be investigated in the preliminary design phase. The model testing program will provide an opportunity to optimize the hull form for open water and ice capability. A full test program could include testing with and without reamers and wedge. •

Seakeeping versus ice capability

In general we expect that the icebreaking hull form features, i.e. the ice wedge and reamers, will improve the seakeeping performance of the vessel. One important decision with regard to seakeeping is whether to install bilge keels. Bilge keels provide substantial roll damping and would result in a much more seakindly vessel. However, ice operations subject appendages such as bilge keels to a high risk of damage. Structurally integrating the bilge keels with the hull form has been one successful solution implemented on some icebreakers, such as the Fennica. The design includes a transducer “centerboard” as a way of avoiding bubble sweepdown. The centerboard also provides some roll reduction in a seaway. In the preliminary design phase, we will attempt to quantify this and prepare a comparison of the centerboard’s roll reduction capability versus bilge keels. •

Range and endurance versus vessel size and cost

The endurance is what drives the size of the ship in conjunction with the assumed mission profile. If we are to retain the current mission profile, then we must accept the size of ship that results. Whether or not the mission profile is conservative or non-conservative could be debated because of the highly variable nature of the operating environment from place to place and year to year. For design purposes, one has to make some assumptions, and the profile assumed is realistic for Alaskan waters. Whether or not the resulting vessel size is a problem will be a point for discussion.

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15. CONCEPT DESIGN DRAWINGS The Alaska Region Research Vessel concept design drawings include the following: •

Lines Plan, Dwg No. 00100-1

•

Outboard Profile, Dwg No. 00100-2, sheet 1 of 4

•

Inboard Profile, Dwg No. 00100-2, sheet 2 of 4

•

Upper Decks, Dwg No. 00100-2, sheet 3 of 4

•

Lower Decks, Dwg No. 00100-2, sheet 4 of 4

•

Typical Stateroom, Dwg No. 00100-3

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16. SCIENTIFIC MISSION REQUIREMENTS The Scientific Mission Requirements for an intermediate, ice-strengthened, general purpose and fisheries oceanography research vessel follow. Revisions: September 2000 and March 2001

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