1/28/2005

(This letter and associated tables can be downloaded as a pdf document by clicking <Ocean_Class_Hull_ltr012805.pdf>.)

Request for Community Comment on UNOLS Ocean Class Hull Form
Recommendation to ONR

I. Introduction

The U.S. academic oceanographic research fleet is in the process of renewal as described in the 2001 Federal Oceanographic Facilities Committee (FOFC) Plan <http://www.geo-prose.com/projects/fleet_rpt_1.html>. Many of the Regional and Ocean Class vessels are approaching the end of their life cycles. The planning for new regional vessels is underway with funding from the National Science Foundation (NSF). A major concern, however, has been that the Ocean Class vessels were fast approaching their decommissioning dates without any new vessels (or the funds to build them) in sight. Recently the NSF National Science Board approved funding from the Major Research Equipment (MRE) account for the Alaska Region Research Vessel (ARRV). The design is essentially done for this ice capable Ocean Class vessel and we now wait for Congress to approve the funding to build it. The need, however, is for additional vessels in the Ocean Class to replace the other aging intermediate vessels.

A year ago, the Office of Naval Research (ONR) provided funding for a concept design study of three Ocean Class hull types, the monohull, the SWATH, and the X-Craft (a high speed catamaran). At the annual meeting of UNOLS in October 2004, RADM Cohen of ONR presented a plan to fund the construction of additional Ocean Class Research Vessels with special emphasis on the X-Craft as a potential future platform. RADM Cohen felt strongly that in the future, the practice of oceanography would be enhanced by having faster research vessels, more portable-van-based laboratory space that could be quickly moved on and off the vessel and enclosed in a climate controlled space, helicopter and autonomous aircraft access and support, and much more extensive handling capabilities for fleets of autonomous underwater vehicles (AUVs). He charged UNOLS to look carefully at this hull design in collaboration with the naval architectural firm John J. McMullen Associates, Inc. (JJMA) and to compare it to the other two hull forms currently under consideration. He provided a timetable for reaching an informed choice by early 2005 because funds for constructing the first of the new Ocean Class vessels could be in place as early as FY06.

The UNOLS Fleet Improvement Committee (FIC) and the Ocean Class Advisory Committee (OCAC) have been working with JJMA on an accelerated evaluation of the different hull types (as described below) and we have reached a point where community input about our findings is now essential to the process of making the final recommendation. Please read the following information about the process that has been followed and the results of the evaluation. We seek your comments about the process and results. Responses by 8 February would be most useful.

II. Science Mission Requirements & Hull Comparisons

Development of UNOLS Science Mission Requirements (SMRs) for Ocean Class vessels began in earnest in February 2002. Starting with the broad parameters for the class given in the FOFC Plan, an Ocean Class Steering/Advisory Committee <http://www.unols.org/committees/fic/ocean/ocean_class.html#Occommittee> conducted a large community SMR definition workshop and solicited broad user community comment on the draft SMRs. This process culminated in publication of the SMRs in March 2003 <http://www.unols.org/committees/fic/smr/ocean/ocsmr_version1.html>. They constitute a substantial body of interdisciplinary and broadly-based thought about the anticipated scientific needs and uses for these new vessels.

Beginning shortly after SMR publication, ONR supported interactions between the UNOLS FIC, OCAC, and a naval architectural team from Naval Sea Systems Command (NAVSEA) and JJMA to translate the SMRs into notional vessel designs. The vessel types under consideration are – (i) a conventional monohull, somewhat reduced in size and scope from the AGOR 23/4/5 Global Class ships, (ii) a SWATH form similar to AGOR 26 (Kilo Moana), and (iii) an X-Craft, modeled after the vessel now under construction for ONR at Nichols Bros. Shipyard <http://www.nicholsboats.com/current_projects.htm>. A series of meetings and web conferences ensued; meeting minutes and conference presentations are listed at <http://www.unols.org/_projects/fic_ocean/xcraft/xcraft_documents.html>. For each hull type this process resulted in several cycles of notional vessel arrangements and calculations of key parameters (draft, cost, seakeeping capability, etc.) presented by the designer team, UNOLS comments on the pros and cons of these notional results from the standpoint of scientific efficacy, and refinements and amendments taking stock of those comments.

At a meeting and X-Craft shipyard visit on November 16-17, 2004, ONR introduced several additional desiderata from the standpoint of future Navy uses of the ships. These objectives had not been explicitly noted in the existing SMRs, though some aspects (e.g. van capacity) had been discussed to varying degrees. These additional "Navy SMRs" were then included in subsequent hull form assessments and discussion and were, as noted below in Section III, given weights and scores along with the pre-existing UNOLS SMRs. This document is a call for community comment on the weighting and scoring, prior to forwarding a final hull recommendation to ONR. We especially solicit comments from ship users (e.g. users of AUVs and UAVs) likely to have particular interest in the "Navy SMRs."

As a result of this series of meetings, each hull form was developed in two or three variants, details of which are given in documents for the Dec. 20, 2004 web conference:

• Monohull: baseline ship, a lengthened ship with additional hangar space, and a wide-beam variant
• SWATH: versions with large and small hangars, reflecting tradeoffs between open deck space and enclosed space
• X-Craft: Three different hangar sizes, reflecting tradeoffs similar to the SWATH situation.

Upon consideration of these variants the UNOLS group recommended at the Jan. 5, 2005 meeting that further consideration be restricted to one variant of each type: slightly lengthened "baseline" monohull, "small-hangar" SWATH and "small-hangar" X-Craft [simplified arrangement drawings for each of these hull forms are available at <http://www.unols.org/_projects/fic_ocean/xcraft/JJMAslides_012505.pdf>]. These down-selections reflected many factors. Importantly (but not exclusively), the "baseline" monohull was deemed sufficiently responsive to SMRs (including provision for eight internal vans) that a significantly enlarged length or beam was not necessary or cost-effective, and the "small-hangar" choices for the other two forms reflected a concern for retaining a useful amount and arrangement of open deck area for a number of near-surface scientific purposes (coring, instrument recovery alongside, etc.). Subsequent design refinements and eventual scoring were carried out using these three hull forms, one of each type.

III. Hull Evaluation Process and Scoring

The evaluation of the relative suitability of the three basic hull forms was based on the UNOLS and Navy SMRs. Generally only those SMR elements that would be impacted by the choice of hull form were considered in this evaluation. As an example, computer networking was not scored because it was felt that excellent computer networking could be accomplished in any hull form.

The spreadsheet tables below list the SMR elements that were evaluated by our group and the relative importance for that element expressed as a weight. SMR elements were rated as being of high importance (weight of 9), medium importance (weight of 5) or lower importance (weight of 1). The weights assigned by the different members of the group were averaged to arrive at their relative importance. This is in effect a rank ordering of the various SMR elements. Each element is more completely defined by the appropriate section in the published SMRs (linked in the table below) or is explained in comments in the table. The relative importance of the SMR elements or areas of emphasis is independent of any hull form or design considerations, but is an evaluation of how important this element is to the successful completion of future science missions.

The relative strengths of the different hull forms in meeting the SMRs were rated on a scoring scale of 7: Excellent, 5: Very Good, 3: Good, 1:Fair and -1: Poor. Based on the information in the several reports provided by JJMA each hull form was examined to determine how well it met the SMRs (see spreadsheets).

The construction costs of the vessels depended basically on the amount of steel or aluminum used. In steel, the monohull is the least expensive to construct. The SWATH and X-Craft are roughly 20 percent more expensive to construct. An aluminum version of either twin hull-form is much more expensive. The estimated day rates are $21,250 for the monohull, $23,000 for the SWATH, and $23,500 for the X-Craft; the two twin-hull versions have higher maintenance and fuel costs. In general, it was found that the monohull excelled in certain operations such as long coring capability, recovery of free floating instruments requiring unobstructed side exterior passageways and lower freeboard for over-the-side handling. Construction constraints for the SWATH and X-Craft versions put limitations on the working deck arrangement as well. The larger structural space within the X-Craft and SWATH vessels allows for easier arrangement of the required number of science accommodations. This additional space makes helicopter operations, preparation of AUVs for deployment, UAV operations, and interior location and handling of vans somewhat easier for the X-Craft and SWATH.

Some of the hull forms have serious limitations. For example, a variable-ballast SWATH version is necessary to have a draft less than 20 feet, which is needed to access many normal ports of call. It is also difficult to install a 1-degree multibeam on either the SWATH or X-Craft vessel. The SWATH and X-Craft have greater difficulty meeting the variable science payload requirement. With the larger superstructure (windage), maneuverability at low speeds, station keeping, and dynamic positioning are harder to achieve than with a monohull.

The monohull essentially meets the seakeeping SMR. The SWATH exceeds the SMR by a wide margin. The X-Craft falls short of the SMR because of high lateral accelerations and roll. Bubble sweepdown on the SWATH is less due to its deeper draft and better seakeeping. Sweepdown remedies have been engineered for monohulls; remedies for X-Craft are more speculative. Sonar self noise and radiated noise are thought to be a greater concern for the twin-hull versions compared to the monohull.

IV. Request for Community Input:

A summary of the SMR scoring for each of the three hull variants is provided in two tables below. The first table is the result of averaging the weights and scores as determined by eleven members of the UNOLS working group. The second table is the same as the first table with the Navy SMRs arbitrarily given the highest possible weights to gauge the impact of the Navy SMRs on the final results. At the bottom of each table, the total weighted scores have been normalized by the monohull weighted score for ease of comparison.

Please review this information and the associated web documents and provide us with your feedback. We particularly invite your opinion about which hull form would best serve the oceanographic community in the future. Feedback can be submitted by completing the text box below or by sending an email message to the UNOLS Office at office@unols.org. Input received by February 8, 2005 would be most useful.

Sincerely,

Ocean Class SMR Tables

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