SAWE Technical Papers

@inproceedings{3776,

title = {3776. Harnessing Historical Company Data for Estimating Weights of Customized Commercial Workboats},

author = {Chandan Deol and Lindsay Johnston},

url = {https://www.sawe.org/product/paper-3776},

year  = {2022},

date = {2022-05-21},

urldate = {2022-05-21},

booktitle = {81st Annual Conference, Savannah, Georgia},

pages = {33},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Savannah, Georgia},

abstract = {Robert Allan Ltd., Canada’s most senior Naval Architecture and Marine Engineering firm, specializes in the design of ship-handling tugs and other workboats for a global clientele. On average one to two vessels designed by the firm are launched every week. Almost every vessel is tailored to meet the needs of the client, even if it is based on one of several common hull types. This design flexibility presents a challenge when it comes to estimating weights efficiently and accurately. 

Fortunately, Robert Allan Ltd. can draw on a significant historical database that can be leveraged when estimating vessel weights and centers of gravity for new projects. Over the last six years, the weight engineering team has worked to build a more efficient, rigorous, consistent, and accurate weight estimating procedure for tugs and other commercial workboats while still allowing for client-driven design customization. 

This paper summarizes the process of collecting and utilizing historical data to develop a tool to estimate weights and centers of gravity for a new vessel based on the limited number of inputs available at an early phase of design. It will also address how the development of this tool, which has become a key component of the firm's weight estimating process, has revealed key areas where more specialized tools are required to improve accuracy and efficiency. This has led to Robert Allan Ltd. developing a collection of specialized weight estimating tools and guidelines that address these key areas and cater to the different design phases. Although these tools have evolved to a point where they are widely used throughout the firm, they continue to be modified and upgraded to meet new requirements and include new data.},

keywords = {13. Weight Engineering - Marine},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3738,

title = {3738. Aft Perpendicular... An Afterthought?},

author = {Scott Daley and Rob Dvorak and Matt Marburger},

url = {https://www.sawe.org/product/paper-3738},

year  = {2022},

date = {2022-05-21},

urldate = {2022-05-21},

booktitle = {81st Annual Conference, Savannah, Georgia},

pages = {12},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Savannah, Georgia},

abstract = {How do you define the length of a ship? What is the definition of aft perpendicular? From the Principles of Naval Architecture (PNA), the definition for the location of the aft perpendicular “is at the aft side of the rudder post, centerline of the rudder stock, or at the intersection of the design waterline with the aft end of the vessel.” However, for U.S. submarines, the location of the aft perpendicular has not always followed PNA’s definition. The location for a submarine’s aft perpendicular has been at the end of the thrust device or at an outdated feature. This paper will examine the technical details, design maturity and timeline, and implications of how the aft perpendicular on a submarine is defined.},

keywords = {13. Weight Engineering - Marine},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3771,

title = {3771. A Look at Inclining Experiment Heel Angles: Measurement Tools and Sensitivity},

author = {David Tellet},

url = {https://www.sawe.org/product/paper-3771},

year  = {2021},

date = {2021-11-01},

urldate = {2021-11-01},

booktitle = {2021 SAWE Tech Fair},

pages = {27},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Virtual Conference},

abstract = {An inclining experiment is used to indirectly measure the vertical center of gravity of a ship by measuring resultant heel angles for a given weight moved athwartships. The methods for measuring these angles are considered tried and true even though the uncertainties of their accuracy and precision are not well understood. This paper explores the impact of errors from traditional inclining methods and compares them with modern methods. The paper looks at a simulated inclining experiment and explores the change in results when errors are introduced into the measurements. It then looks at electronic inclinometers used in an actual inclining and discusses how that data can be analyzed and how that might affect the results of the experiment. Finally the paper discusses the advantages and disadvantages of old and new methods and provides recommendations for improved results from future inclinings.},

keywords = {03. Center Of Gravity, 13. Weight Engineering - Marine},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3774,

title = {3774. Weight Control For Floating Wind Installation},

author = {A. P. Crowle and P. R. Thies},

url = {https://www.sawe.org/product/paper-3774},

year  = {2021},

date = {2021-11-01},

urldate = {2021-11-01},

booktitle = {2021 SAWE Tech Fair},

pages = {10},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Virtual Conference},

abstract = {Floating offshore wind is a growing market within the renewable energy sector. The floating offshore wind turbines give access to deeper water sites, with minimal visual impact from land. The paper includes the weight control requirements for Spars, barges, semi submersibles and Tension Leg Platforms (TLPs) as floating wind platforms. 

There are weight control challenges for the various substructure types during the temporary phases of construction and offshore installation. An accurate assessment of the buoyancy of the floating wind turbine for different drafts and trims is required. Allowances need to be included in the weight calculation for temporary buoyancy, sea-fastenings and grillage. 

Weight control for installation has an influence on the weather window for the floating substructures during transportation to the offshore site and mooring and electrical connection. The paper will cover weight calculation methods during early design, detailed design, construction, installation, operation and demolition. 

The installation process for a floating wind turbine varies with substructure type and this paper will give an overview of the weight control requirements for loadout, ocean transport and mooring connection. The floating offshore wind turbine weight and centre of gravity has a direct bearing on draft, intact stability and motions. As part of the weight control process the centre of gravity and radii of gyration need to be accurately determined for each stage of the installation.},

keywords = {13. Weight Engineering - Marine, 24. Weight Engineering - System Design, 35. Weight Engineering - Offshore, Student Papers},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3741,

title = {3741. Finding the Balance Between Accuracy and Practicality in Deadweight Survey},

author = {Colin MacFarlane and Manuela Bucci},

url = {https://www.sawe.org/product/paper-3741},

year  = {2020},

date = {2020-07-01},

booktitle = {2020 SAWE Tech Fair},

pages = {24},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Virtual Conference},

abstract = {Deadweight audits are exercises required to calculate the vessel lightweight by deduction from the actual ship weight. Depending on the size of the vessel, they can take a few hours to several days. Minimising the duration of the exercise should be prioritised since accuracy of the result is connected to avoidance of changes in the recorded vessel's configuration during the audit. This leads to a compromise between precision and the accuracy that can be achieved: estimating the weight of the deadweight based on experience is the quickest method, weighing everything with calibrated scales is the most precise. An intermediate solution is to find the deadweight partly with estimates, partly with weighing.Experience with all three of these methods showed that accuracy can be achieved even if relatively poor resolution is accepted, if some precautions are taken when recording the weights.This paper presents three study cases and the calculation of uncertainty in the deadweight that derived from the different approaches. The uncertainty and the time spent to complete the audit are used to define an efficiency estimator to rate the deadweight audit.The conclusion is a method to upgrade data recording that allows production of a more meaningful result.},

keywords = {08. Weighing, 13. Weight Engineering - Marine, 21. Weight Engineering - Statistical Studies, 35. Weight Engineering - Offshore},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3711,

title = {3711. A Century of Submarine Mass Properties},

author = {David Tellet},

url = {https://www.sawe.org/product/paper-3711},

year  = {2019},

date = {2019-05-01},

booktitle = {78th Annual Conference, Norfolk, VA},

pages = {41},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Norfolk, Virginia},

abstract = {This paper takes a chronological look at submarine milestones during the last century and discusses how the evolution of submarine design affected mass properties engineering including weight control processes, management of mass properties, technical authority, and stability and buoyancy requirements. The paper discusses how the movement of submarine design from boats that can submerge to submarines designed for near constant submergence changed performance requirements including mass property limits. It discusses how the Cold War and nuclear power influenced submarine design and how this affected mass properties requirements and practices including deliberate margin depletion and reduction in service life margins. The paper includes some thoughts on future submarine designs and how those may affect mass property management practices.},

keywords = {13. Weight Engineering - Marine},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3715,

title = {3715. Negligible Weight Quantification for Surface Ship Weight Surveys},

author = {Greg Roach},

url = {https://www.sawe.org/product/paper-3715},

year  = {2019},

date = {2019-05-01},

booktitle = {78th Annual Conference, Norfolk, VA},

pages = {12},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Norfolk, Virginia},

abstract = {Shipboard weight surveys are routinely performed for surface vessels across the spectrum of marine industries from small pleasure craft to large surface combatants. These surveys are typically part of a vessel's stability test (weight survey & inclining experiment) usually required as part of the vessel's delivery/acceptance or during its service life to confirm the safety of the vessel and/or crew/passengers has not been compromised from post-delivery modifications or inevitable weight & KG growth. These stability tests may take a few days to a few weeks, with a large portion of the effort attributed to the weight survey itself. Further, a large portion of the survey consists of inventorying smaller items which typically constitute a relatively small portion of the overall weight nor may have any appreciable impact to the overall results of the stability test.To date (to the author's knowledge), no official guidance or recommendation(s) exists on what or how to quantify as negligible weight(s) for the purposes of a weight survey. This guidance, if available, may reduce the time required for survey and save considerable time and resources without appreciably changing the end result and/or conclusion.With limited availability/diversity of actual ship survey data, the analysis will focus on the required precision of the stability test based on accepted requirements documentation. This analysis will consider the size of the vessel which directly impacts the design's sensitivity to weight, as well as the practicalities associated with the existing practices of shipboard surveys such as availability of the vessel or qualified personnel. In addition, industry guidance on human engineering design will be used to establish 'rules of thumb' for determining item weights and/or their potential impact to the results to aid in shipboard surveys.},

keywords = {13. Weight Engineering - Marine, 25. Weight Engineering - System Estimation},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3717,

title = {3717. Evaluating a CoG Envelope Using a Probabilistic Approach},

author = {Robert J. Hundl},

url = {https://www.sawe.org/product/paper-3717},

year  = {2019},

date = {2019-05-01},

booktitle = {78th Annual Conference, Norfolk, VA},

pages = {15},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Norfolk, Virginia},

abstract = {In the Energy and Chemicals Construction Industry, many onshore projects are using modular construction. This type of construction requires that the modules be transported from the fabrication yard to the project site. The fabrication yard may be distant from the project site, thus requiring a combination of ocean transportation and land transportation. To verify the design, the structural analysis uses a given design weight limit and center of gravity (CoG) envelope for the various modes of transportation. The size of the CoG envelope can influence the strengthening requirements for the structure during the transportation phases. CoG envelopes are typically set as a percentage of the module length and width. In special cases, a probabilistic approach could be used to reduce the typical CoG envelope size for reducing the amount of strengthening requirements while also quantifying the risk to the project for reducing the size of the CoG envelope.},

keywords = {13. Weight Engineering - Marine, 21. Weight Engineering - Statistical Studies, 35. Weight Engineering - Offshore},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3718,

title = {3718. Center of Buoyancy and Center of Gravity Measurement of a Submersible Vehicle},

author = {James Blair},

url = {https://www.sawe.org/product/paper-3718},

year  = {2019},

date = {2019-05-01},

booktitle = {78th Annual Conference, Norfolk, VA},

pages = {16},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Norfolk, Virginia},

abstract = {Stability of submersible vehicles is dependent on the relationship between the center of gravity and center of buoyancy locations on the object. Improper relationships between the two can reduce performance and adversely affect the mission goals of the vehicle. Measuring these values can reveal variations from the designed values that may have been introduced during the manufacturing or assembly process. These values can also change in modular submersible vehicles which allow swapping or modifying components based on the needs of their mission. Errors associated with an improper relationship may not arise until sea testing, which may lead to the need for vehicle disassembly in order to shift or change ballast weights of the submersible.This paper examines a measurement system designed to measure the center of gravity and the center of buoyancy of a submersible object using a hanging weight and center of gravity instrument. The method demonstrated is applicable for vehicles ranging from a few pounds to upwards of 15 tons. With proper fixturing, the machine is capable of measuring center of buoyancy and center of gravity in all 3 axes, which can help determine lateral, longitudinal, and directional stability of a part. This paper outlines a process for measuring submersible vehicles (with negative or slightly positive buoyancy) to determine weight, buoyant force, center of gravity, and center of buoyancy.},

keywords = {13. Weight Engineering - Marine, 21. Weight Engineering - Statistical Studies},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3719,

title = {3719. Modernising Ship Stability: Lightship Evolution Diagnostics with In-Service Stability},

author = {Manuela Bucci and Colin MacFarlane},

url = {https://www.sawe.org/product/paper-3719},

year  = {2019},

date = {2019-05-01},

booktitle = {78th Annual Conference, Norfolk, VA},

pages = {24},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Norfolk, Virginia},

abstract = {Lightship mass and center of gravity are the basis for assessing ship regulatory stability and the maximum payload that the ship can load results from this assessment. Knowing the ship mass and centre of gravity is therefore of utmost importance for both commercial and safety reasons.It is known that, over time, both these quantity change. At present, changes in the lightship are addressed by five-yearly audits that may lead to an inclining experiment - the traditional way to measure ship mass and centre of gravity. The time gaps are filled with estimates based on weight control which can be shown to be a 'random walk' process. This means that, temporarily, undetected worsening of the ship stability might occur.Draught measurement provides immediate feedback of the accuracy of the estimate of weight change, provided draught sensors are adequately maintained. Evidence of change in the vertical position of the lightship center of gravity is not, however, obvious.In-service stability measurements, integrated into the vessel's operational routine, directly estimate the vessel VCG and can diagnose changes in the lightship vertical moment using statistical process control techniques. Changes in the progression of mean values of Deadweight and Lightship vertical moment are used instead of records of weight changes to build a model of ship stability over time with uncertainty on the mean value decreasing with increasing number of measurements. Weight control remains important to characterize the changes and discrepancies from the loading program can be used to identify sensor failures, defective estimates of cargo deadweight and Lightship changes.This paper briefly reviews conventional techniques (referring to previous Conference papers). It then discusses attempts to perform conventional inclinings at sea and the difficulties in obtaining precision, before setting out the methods of in-service stability assessment, techniques for analysis of the results and finally the control limits that can be used to trigger further investigation. The technology is suitable for autonomous vessels.},

keywords = {13. Weight Engineering - Marine, 21. Weight Engineering - Statistical Studies},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3698,

title = {3698. Weights, Center and Inertia Modeling of the Sinking Analyses of the El Faro},

author = {Sean Kery and Dominick Cimino and Paul Bragulla},

url = {https://www.sawe.org/product/paper-3698},

year  = {2018},

date = {2018-05-01},

booktitle = {77th Annual Conference, Irving, Texas},

pages = {22},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Irving, Texas},

abstract = {The analysis of a ship experiencing downflooding must begin with a careful understanding of the unflooded and undamaged condition as a point of departure. From there the consumables can be adjusted vs time and the flooding can be added to successive weights calculations to build out the probable downflooding and stability progression.The 790 foot SS El Faro was lost with all hands October 1st, 2015 off the Bahamas near the eye of Hurricane Joaquin, by progressive flooding and eventual capsizing. CSRA supported the National Transportation Safety Board (NTSB) investigating the sinking by providing dynamic modeling and simulation of the accident voyage.The weights, centers and inertias of this 40 year old, much modified vessel was complicated by out of date and incorrect technical drawings, minimalist CargoMax load out documentation and lack of other critical information. While the results of the analyses were adequate to support the further modeling, they were marred by having to estimate the weights and centers in a number of areas. Sensitivity studies were used to evaluate the impact of errors in the roll, pitch and yaw gyradii on the motions in hurricane seas.},

keywords = {13. Weight Engineering - Marine},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3673,

title = {3673. A Recommended Weight Margin Approach for Wet Undersea Vehicles},

author = {William Boze},

url = {https://www.sawe.org/product/paper-3673},

year  = {2017},

date = {2017-05-01},

booktitle = {76th Annual Conference, Montreal, Canada},

pages = {7},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Montreal, Canada},

abstract = {Non-pressurized fully flooded (or 'wet') undersea vehicles are sensitive to weight and buoyancy changes. Thus, wet vehicles as they will be referred to from here on out, need the application of both an uncertainty margin for weight and buoyancy prediction during the design development phase. Classical margin approaches for addressing risk uncertainty in surface ships or pressurized submersible vehicles do not address buoyancy uncertainty. This is primarily due to establishing and locking-in the surface ship hull or the pressure hull of a submersible vehicle early in the design. Therefore, margin approaches that address both weight and buoyancy uncertainty during wet undersea vehicle designs appear to be needed.},

keywords = {13. Weight Engineering - Marine},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3674,

title = {3674. A Weight Analysis of Civil War Ironclad CSS Virginia},

author = {Nicholas E. Marickovich},

url = {https://www.sawe.org/product/paper-3674},

year  = {2017},

date = {2017-05-01},

booktitle = {76th Annual Conference, Montreal, Canada},

pages = {79},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Montreal, Canada},

abstract = {This paper presents a weight analysis of and radius of gyration calculations for the Civil War Ironclad CSS Virginia, built by the Confederate States Navy to attempt a break of the Union Blockade of Hampton Roads in Southeastern Virginia in 1862. The weight analysis was done in conjunction with a larger naval architecture analysis accomplished as a master's thesis for an MS in Ocean Engineering from Virginia Tech. This paper specifically reports the weight and radius of gyration analyses, and notes some of the conclusions that can be made based on the ship's weights, basic hydrostatic properties, and estimated center of gravity.The paper begins with a brief overview of the history behind the CSS Virginia, including the development of ironclad vessels up to 1862. The service life of the Virginia is briefly discussed to lend the weight analysis context.The paper then discusses the weight analysis and radii of gyration calculations in detail. The weight analysis utilized a geometry model of the Virginia made using Paramarine software, as well as historical information in the form of model plans, books, articles, and other sources. Microsoft Excel was used to track the weights for the estimate, and a variety of methodologies were used to estimate different aspects of the ship's weight and center of gravity. The different items examined included but were not limited to:* Ship's structure (the hull, decks, iron armor, etc.)* Armaments and ammunition* Provisions* Weight of personnel serving on board and their effects* Propulsion machinery weightsThe weight estimate was used to develop radii of gyration calculations based on weight distributions per SAWE RP-17, Weight Distribution and Moments of Inertia for Marine Vehicles.In the thesis (Marickovich, 2016), the information from the weight estimate was taken as an input for a larger naval architecture analysis of the CSS Virginia, particularly in regards to seakeeping. The results of the weight estimate are presented here, as are results from the analysis pertaining to initial stability (which is largely dependent on the ship's vertical center of gravity). The overall results of the seakeeping analysis are very briefly mentioned, as well as a hypothesis questioning certain aspects of the history surrounding the Virginia's destruction which is based on the ship's hydrostatics. Readers interested in the broader naval architecture analysis should consult the full thesis, which is available through Virginia Tech's ETD database.},

keywords = {13. Weight Engineering - Marine},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3676,

title = {3676. Weight Control: Idealistic vs. Realistic},

author = {R. Alan Bird},

url = {https://www.sawe.org/product/paper-3676},

year  = {2017},

date = {2017-05-01},

booktitle = {76th Annual Conference, Montreal, Canada},

pages = {14},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Montreal, Canada},

abstract = {Often, the requirements for determining the mass properties of a ship are contractually establishedbythecustomerand/orthedesignagent. Inreallifethough,withintheshipyard, many of those requirements physically can't be done, are in themselves not accurate, or fall by thewaysideduetocostand/orschedulefactors. EveninsomeoftheRecommendedPractices, there are 'requirements' that are misconceived. This paper discusses several examples that can (and will) deter from what would be an 'idealistic' weight control program.},

keywords = {13. Weight Engineering - Marine},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3677,

title = {3677. Considerations for Reviewing Ship and Submarine Weight Reports},

author = {David Tellet},

url = {https://www.sawe.org/product/paper-3677},

year  = {2017},

date = {2017-05-01},

booktitle = {76th Annual Conference, Montreal, Canada},

pages = {22},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Montreal, Canada},

abstract = {Ship weight control must be practiced diligently in both the cus- tomer's and the contractor's organizations. Part of the customer's weight control process is the careful review of periodic weight reports that are produced and submitted by the contractor. The purpose of this paper is to present some considerations for the proper review of these weight reports including basic requirements, tools available to the reviewer, knowledge the review should have, the approach to the review, reviewing accepted weight reports, reviewing quarterly weight reports, common issues, schedules, and areas of concern during weight audits.},

keywords = {13. Weight Engineering - Marine},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3678,

title = {3678. Submarine Static Stability},

author = {David Tellet},

url = {https://www.sawe.org/product/paper-3678},

year  = {2017},

date = {2017-05-01},

booktitle = {76th Annual Conference, Montreal, Canada},

pages = {39},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Montreal, Canada},

abstract = {This paper complements [Tel07] and discusses basic sub- marine stability. Areas covered include submarine arrange- ments, centers of gravity and buoyancy, hydrostatics and volumetrics, the principle of the metacenter, types of stabil- ity (including surfaced, submerged, damaged, longitudinal, transitional, and under-ice), stability criteria, and a section on how to calculate stability. The appendix includes typical calculation forms and a discussion of free surface moments and how they are calculated.},

keywords = {13. Weight Engineering - Marine},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3687,

title = {3687. An Updated Initial Parametric Weight Equation Compendium},

author = {David Hansch},

url = {https://www.sawe.org/product/paper-3687},

year  = {2017},

date = {2017-05-01},

booktitle = {76th Annual Conference, Montreal, Canada},

pages = {50},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Montreal, Canada},

abstract = {When developing the initial weight estimate for a new vessel, the weight engineer or naval architect can produce his or her estimate either by scaling from a known, similar vessel, or by taking the weights of each portion of the vessel from parametric equations or by some combination of these two methods. The preferred source of a parent vessel to scale from or the data from which a parametric equation is derived is the past vessels designed by the naval architect's own firm; however, sometimes the firm may not have suitable designs in its portfolio to base a new design weight estimate upon. This paper seeks to collect as many previously published parametric weight equations for as wide a collection of vessel types as possible in order to provide a convenient reference for the times the naval architect's own data is insufficient to complete a weight estimate.This paper is not intended to be the definitive source of parametric weight equations, rather, the goal is to collect a critical mass of equations across the range of vessel types to start the conversation on the relative merits of the various equations and hopefully elicit new up-to-date equations from others. Ideally discussers will add equations based on their own data in addition to discussing the merits of those collected here. The end goal is the production of a SNAME T&R Bulletin, however much additional validation, updating and discussion is required to take the current paper to the point where it could be considered as a true draft for such a bulletin.In all cases, the reader is encouraged to consult the original source and attempt independent validation before using any of the equations collected herein.},

keywords = {13. Weight Engineering - Marine},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3693,

title = {3693. A Random Method for Picking Module Stowage Solutions for Barges},

author = {Robert Hundl},

url = {https://www.sawe.org/product/paper-3693},

year  = {2017},

date = {2017-05-01},

booktitle = {76th Annual Conference, Montreal, Canada},

pages = {15},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Montreal, Canada},

abstract = {In the Oil & Gas Construction Industry, many onshore projects are using modular construction. This type of construction requires that the modules be transported from the fabrication yard to the project site. The fabrication yard may be distant from the project site, thus requiring ocean transportation. Modules can come in many different sizes, shapes, and weights. Some very large modules require a dedicated barge. However, frequently multiple modules can be placed upon a single barge. Determining module groups for barges can be difficult and time consuming. Figure 1 shows several different types of modules on barges.Determining the type of barge to use, the number needed, and the length of service time can be a daunting logistical task. Costs involved with securing barges and engineering services from barge companies are in the millions of dollars. To complicate matters, barges typically require long lead times. Determining what type of barge or the appropriate 'mix' of barges to use can help reduce the cost of the project.This paper will demonstrate a method to easily solve for a group solution through the use of a random number generator and grading the resultant solutions. This method can easily be applied to other types of problems and industries when it is necessary to pick groups to solve the problem.},

keywords = {13. Weight Engineering - Marine, 21. Weight Engineering - Statistical Studies, 35. Weight Engineering - Offshore},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3669,

title = {3669. Light Ship or Load? Uncertainty in Shipboard Weight Surveys},

author = {Nicholas Marickovich},

url = {https://www.sawe.org/product/paper-3669},

year  = {2016},

date = {2016-05-01},

booktitle = {75th Annual Conference, Denver, Colorado},

pages = {10},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Denver, Colorado},

abstract = {Adequate stability for a ship is critical to the vessel's safety and operation, the safety and well being of its crew and passengers, and its ability to accomplish its mission. To validate that a ship has acceptable stability, a detailed inventory of the ship is conducted to determine what weights must be added or deducted in order to arrive at an accurate light ship center and weight. This determination is important in arriving at the ship's true light ship weight and center, a basis for calculating the ship's draft, trim, and stability characteristics. Small vessels may only require a couple of people and a few hours to complete such a survey while a larger vessel, on the other hand, can require several thousand manhours and more than a week to perform. The accuracy of this important survey depends on the available manpower, the experience of the surveyors, the size and complexity of the ship, and, most importantly, the accuracy and consistency practiced by the people conducting the survey. 

Currently, there are two guidance documents: the Navy's Naval Ships Technical Manual (NSTM) Chapter 096, Weight and Stability, and the Society of Allied Weight Engineer's (SAWE) Recommended Practice M-9, Shipboard Weight Surveys. However, it has been observed that there are still many areas of inconsistency from one surveyor to the next, one type of ship to the next, one shipyard to the next, and even from one Navy observer to the next. There are also new trends observed on naval vessels that need to be factored into a ship survey such as the growing trend of increased shipboard items introduced by the ship's force to improve quality of life, increased stores, and increased equipment that may or not be a permanent fixture on the vessel. Currently, these items default to a judgment call by the individual surveyor or the organization conducting the survey. This inconsistency causes inaccuracy and reduces the value of conducting these surveys. It also reduces the value of the data to determine trends and to compare one ship to another. How much inaccuracy is inherent in this process is not known and cannot be easily measured. 

It is the intent of this paper to identify areas of actual or potential inaccuracy and inconsistency and offer suggestions on how to resolve them Rationale for making a decision as to whether a newly encountered item falls into the light ship or variable load category will also be offered to better enable surveyors to make a reasonable decision during a survey. Guidance will also be provided to determine into which load category new or questionable items should be placed. The main objective is to increase the accuracy of shipboard weight surveys, reduce the inaccuracy of shipboard weight data, and improve the consistency of weight surveys across multiple ship classes and across the industry.},

keywords = {13. Weight Engineering - Marine},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3632,

title = {3632. Challenges Encountered Doing Weight Reports on Multiple Ship Contracts},

author = {R. Alan Bird},

url = {https://www.sawe.org/product/paper-3632},

year  = {2015},

date = {2015-05-01},

booktitle = {74th Annual Conference, Alexandria, Virginia},

pages = {13},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Alexandria, Virginia},

abstract = {Some multi-hull Contracts require that a detailed weight report be generated for only the lead ship in a class, while other contracts require detailed weight reports for each hull in the program. There are many aspects that have to be dealt with for multiple hull contracts primarily, handling hull specific contract modifications. Done incorrectly, dealing with multiple spreadsheets or databases to do weight reports can easily lead to an administrative 'nightmare' and create a great source of errors. This paper discusses an approach used to mitigate duplicate entries and potential errors. It does not go into the details of the revisions made by BAS Engineering to the ShipWeight computer program which added the Phase Code feature, but instead, explains how and why the Phase Codes are used. Proper Database Management is required to ensure consistency, and a time savings (cost) approach to developing weight reports for follow-on ships under multi-hull contracts.},

keywords = {13. Weight Engineering - Marine},

pubstate = {published},

tppubtype = {inproceedings}

}