Ask the MSSC—You have questions. We have answers from the USCG Marine Safety and Security Council.

Why is smoking still permitted on the inside of towing vessels? Over 75 percent of the towing industry smokes. I think this the only place left in this country where you can smoke in the workplace. This is unfair and unsafe for the non-smoking mariner. Any relief in sight?

Answered by the USCG Office of Vessel Activities.


The short answer: No, there is no immediate relief in sight.

However, as of spring 2009, the Coast Guard anticipated publishing a notice of proposed rulemaking for the inspection for certification of towing vessels. As part of that rulemaking, the Coast Guard anticipates there will a discussion concerning mariner safety and health issues. The Coast Guard will open the docket to receive comments on this proposed rulemaking and comments concerning prohibition of smoking on towing vessels are certainly possible.

Absent any specific regulations to prohibit smoking on towing vessels, the Coast Guard encourages you to work with your company’s safety and health committee and see how you can achieve a company-specific policy concerning prohibition of smoking aboard its vessels.

Understanding Vinyl Chloride Monomer

This "Chemical of the Quarter" excerpt is from the U.S. Coast Guard “Proceedings of the Marine Safety & Security Council” magazine, by LT Morgan Armstrong, U.S. Coast Guard Hazardous Materials Standards Division.


Vinyl Chloride Monomer

What is it?
Vinyl chloride monomer (VCM) is considered one of the world’s most important commodity chemicals. In 2007, the global production and consumption of VCM was roughly 79 billion pounds. That is more than 10 billion gallons. The majority of vinyl chloride monomer is used in the production of polyvinyl chloride, also known as PVC. PVC is the largest chlorine-containing end product in the world, and is used in a wide variety of products such as pipes, cars, bottles, lifejackets, wiring insulation, and credit cards.

How is it shipped?
The United States is one of the world’s top exporters, with the majority of manufacturing conducted on the coasts of Louisiana and Texas. It is typically sold directly from the manufacturer to the user. At room temperature and atmospheric pressure, vinyl chloride monomer is a colorless gas; however, it is shipped and stored as a liquefied gas under pressure. VCM is liquefied by moderately increasing pressure or reducing temperature.

VCM is typically shipped in liquid petroleum gas (LPG) ships. It may either be carried in pressurized tanks at ambient temperature or in fully refrigerated tanks at a temperature of 7ºF.

Why should I care?
Shipping concerns. There are several concerns when shipping VCM at low temperatures. These include but are not limited to brittle fracture and ice formation. “Brittle fracture” occurs when metal is rapidly cooled and loses its ductility (or “give”) and impact strength. The metal is then prone to cracking. This is common with steel. Other metals, such as aluminum and special alloy steels and nickels, have improved ductility and impact resistance at low temperatures. However, VCM is not compatible with aluminum and aluminum-bearing alloys. Due to low temperatures, ice can form from moisture in the tank system and block pumps, valves, and lines, causing damage.

When VCM is shipped in pressurized tanks, several issues can arise that are common among all pressurized cargoes, including pressure surges, condensation of trapped vapors, and a liquid free-surface “sloshing” effect, which can decrease stability.

Health concerns. VCM is designated as a human carcinogen. The OSHA permissible exposure limit is one part per million. VCM gas is heavier than air, and replaces air necessary to breathe in confined spaces, causing suffocation hazards. Inhalation of VCM can cause many symptoms, including dizziness, lung irritation, or death, even in a short period of time. Exposure to liquefied VCM can cause frostbite.

Fire or explosion concerns. Due to its highly volatile nature and tendency to form polymeric peroxides, VCM presents a significant fire and explosion hazard. Polymerization occurs when a chemical monomer undergoes a reaction, causing the formation of three-dimensional polymer chains. When polymerization occurs at an uncontrolled rate, it can cause explosions and fire. VCM has a very high evaporation rate and quickly vaporizes and spreads over great distances. It also has a very low flash point of -110°F.

What’s the Coast Guard doing about it?
VCM is regulated under U.S. and international shipping regulations. Stringent regulations are in place for the construction of LPG/gas carriers to ensure compatibility with cargo and maintain cargo and crew safety. Regulations also require that appropriate means be taken to stabilize VCM to prevent polymerization.

Recently there have been several incidents involving VCM leaks aboard foreign LPG carriers in U.S. ports, including one aboard the T/V Venusgas, a Type 2G LPG/gas carrier, at the Port of Corpus Christi, Texas. During the response to an ongoing leak of VCM in the compressor room, several Coast Guard marine inspectors, local law enforcement personnel, facility workers, and ship crewmembers were exposed to vapors and required medical attention and decontamination. The leak was caused by fractured stainless steel indicator lines.

It is crucial in these situations that the ship’s crew is familiar with and immediately implements safety and response procedures. It is equally important for Coast Guard personnel and marine inspectors to maintain awareness of the hazards associated with cargoes while conducting casualty and routine inspections and while responding to cargo spills.


For more information:
Full article is available at http://www.uscg.mil/proceedings/Spring2009/articles/72_Armstrong_Chemical%20of%20the%20Quarter.pdf.

Subscribe online at http://www.uscg.mil/proceedings/subscribe.asp.

Online survey available at: http://www.uscg.mil/proceedings/survey.asp.

Direct requests for print copies of this edition to: HQS-DG-NMCProceedings@uscg.mil.

Responding to Changing Marine Emissions Standards—what a hybrid tugboat means for our environment

Excerpt from U.S. Coast Guard “Proceedings of the Marine Safety & Security Council” magazine by Ms. Susan Hayman, vice president, Health, Safety, Quality, and Environment; Foss Maritime Co.


Matching Power to Need
Hybrid technology minimizes fuel consumption by using a specialized power management system to match required power to the most efficient combination of batteries, generators, and main engines at whatever power level is needed.

If a tug is idling or docked, a lower amount of power will be provided. For escorting or moving a ship, the full horsepower of the tug will be available immediately. There are several different modes of operation for the tugs:

• minimal emissions, with a 0-5% load when idling or stopped;
• eco-cruise, with a 6-19% load during slow transit;
• mid-range, carrying a 20-65% load at faster speeds or while assisting ships;
• full power, carrying a 66% to full load at full-power ship assist speeds.

The Payoff
Tugboats often spend time idling in a harbor or doing tasks less strenuous than full-powered ship assists. When that power is supplied only by diesel engines, resources are spent and unnecessary emissions are created. The hybrid tug will rely on battery power, supplemented by diesel generators and main engines.

We expect the hybrid tug will demonstrate benefits beyond using less fuel and having fewer emissions, such as fuel and lube savings, reduced life cycle costs, and the possibility of the hybrid tug acting as a mobile power generating station.

Also, by using battery power in standby mode and only bringing generators and main engines online when higher power is required, the hybrid tug will be generally quieter than traditional tugs.

For more information:
Full article and “Environmental Protection” edition of USCG Proceedings is available at http://www.uscg.mil/proceedings/Winter2008-09/.

Subscribe online at http://www.uscg.mil/proceedings/subscribe.asp.

Online survey available at: http://www.uscg.mil/proceedings/survey.asp.

Direct requests for print copies of this edition to: HQS-DG-NMCProceedings@uscg.mil

Hybrid Propulsion—what is it, and when does it make sense for ships?

Excerpt from U.S. Coast Guard “Proceedings of the Marine Safety & Security Council” magazine, by Mr. Chris B. McKesson, P.E., consultant; and Mr. Thomas P. Risley, Alion Science & Technology Inc.


What Do We Mean by “Hybrid?”
A “hybrid” drive means there is more than one power source that can turn the shaft, via an electrical interconnection. There might be a combination of batteries and diesel generators, all of which can feed their power into an electric propulsion motor.

What Are the Advantages?
Fuel efficiency. In an ideal hybrid drive system, the system automatically determines the most efficient source of power for a given load demand. In the case of a large passenger vessel, the demands of the “hotel” load and “propulsion” load can be coupled together electrically and powered by a combination of power sources including generators, batteries, and alternative power sources.

In hybrid operation, the engine in the system runs at a constant load. When this load suits the vessel’s propulsion needs, this power is sent to the propellers and consumed in propulsion. But during those times when this power is not needed—during low-speed maneuvers, for example—the engine still produces the power, but it is “banked” in an accumulator array. Then, when required, the accumulator array is drawn upon and its power is added to the still-continuous output of the engine. This steady load is optimal for best fuel consumption.

In the above photo, the propulsion generator is shown in the engine room on a hybrid drive vessel. The cabinet on the right holds propulsion control electronics.

Easy to upgrade. A hybrid drive is inherently modular. Consider a typical hybrid, having one or more diesel generators, a battery bank, and a propulsion motor. In a case like this, you can change out a major component of the system without disturbing the rest. A related advantage is that the individual components are generally smaller and lighter than their traditional counterparts. Thus, the manipulation of any one component is likely to be physically easier.

Arrangeability. This modular or “component architecture” nature of a hybrid drive also brings some potentially important design flexibility: It is possible to put the components nearly anywhere on the boat.

Operational flexibility. In a hybrid drive there is no need for all the generators to be the same size. This system architecture gives the operator the opportunity to decide which power source to have online depending upon the immediate needs of the ship.

What Are the Disadvantages of a Hybrid?
There Ain’t No Such Thing as a Free Lunch. It’s true that a hybrid drive can lower fuel consumption and be more flexible and arrangeable than a conventional mechanical drive. Unsurprisingly, those advantages also come at a cost. In some cases, this cost is financial, but some of the “costs” are measured in other units, such as complexity or weight.

Be Advised: Batteries Are Consumables. Battery choices include lead-acid, advanced glass mat, gel, nickel metal hydride, and lithium ion. For most operators, the lead-acid or advanced glass mat battery is a competitive battery candidate for a hybrid ship, but a lead-acid battery can only survive approximately 1,000 charge/discharge cycles. Eventually it reaches a point where it no longer holds a useful amount of energy. The photo at left shows stainless steel cases on the right-hand side that house large battery banks on a hybrid vessel.

When Does a Hybrid Make Sense?
The best place for a hybrid drive is in an application with a varied duty cycle. Consider the following examples:

A commuter ferry like those in Puget Sound or San Francisco Bay. In these cases the ferry runs are between 30 and 60 minutes long, and turnaround times are fairly short. This type of operation is probably not suited to hybrid drive. We studied hybrid drive for the San Francisco Water Transit Authority and found that, for their nominal 45-minute runs, a hybrid drive would actually result in increased emissions compared to a clean diesel installation. This is because the weight increases associated with hybrid drive resulted in reduced passenger capacity on the ferry, so that the fuel burned was moving fewer people, and the increases in fuel efficiency were not sufficient to compensate for this.

A water taxi. Here, we envision a small-capacity boat making short hops between many closely spaced locales, with passengers hopping on and off frequently. The water taxi may spend as much time idling at the dock as it does underway, like the National Park Service’s Arizona Memorial taxis in Pearl Harbor. These services are ideal for hybrid drive. A quite small generator can be used, which might have a power output as little as one-fourth of the propulsion motor power.

Escort tugs. The tug spends much of its time merely being “available” to a ship, and then providing a significant push for a short time as part of harbor maneuvers. In such a case, it makes little sense to have a 5,000 hp engine running at idle just to lean on it for five minutes per hour. Instead, the hybrid tugs use a substantial battery bank and two small generators that feed the battery bank.

Another situation where a hybrid makes sense is where there is a substantial amount of shore power available. This could apply to a vessel that makes only one or two harbor cruises a day, or a vessel whose turnaround time is so long that it makes sense to plug in and charge up at each dock call.

Given the number of variables and areas for optimization presented by the hybrid concept, it is very important to approach it as an integrated, comprehensively engineered solution.

For more information:
Full article and “Environmental Protection” edition of USCG Proceedings is available at http://www.uscg.mil/proceedings/Winter2008-09/.

Subscribe online at http://www.uscg.mil/proceedings/subscribe.asp.

Online survey available at: http://www.uscg.mil/proceedings/survey.asp.

Direct requests for print copies of this edition to: HQS-DG-NMCProceedings@uscg.mil.

Green Vessel Design—environmental best practices

Excerpt from U.S. Coast Guard “Proceedings of the Marine Safety & Security Council” magazine, by Mr. Brian W. King, P.E.; Mr. Joseph Payne, P.E., LEED-AP; Mr. Ryan Roberts, P.E.; Ms. Christina Villiott, CPSM; all of Elliott Bay Design Group.


As naval architects and marine engineers, we have the opportunity to improve upon design practices and benefit the environment.

Minimize Use of Hazardous Materials and Environmental Contaminates
There are a number of programs that address the use and minimization of hazardous materials and containment. Per “Green Passport,” an International Maritime Organization program, vessel owners are required to maintain accurate records of the potentially hazardous materials that went into the construction of their ships. IMO also addresses issues associated with ship and equipment recycling.

Heating, ventilation, and air conditioning equipment offers an excellent area for improving a ship’s environmental performance. Newer systems are available with a low refrigerant charge per ton of cooling capacity, as well as low global warming potential and ozone-depleting potential.
Minimizing use of volatile organic compounds (VOCs) is another key factor. During ship construction and throughout a ship’s life, use of low-VOC products can improve the air quality of the surrounding community, as well as that of the future occupants of the vessel.

Maximize Use of Recycled and Recyclable Material
The environmental impact of a ship occurs in three distinct stages of its life: construction, operation, and disposal. Green considerations can be applied during vessel design, which will translate to improvements in the construction and operation of a vessel throughout its lifecycle, and provide for greener recycling at the end of the ship’s lifespan.

Steel and aluminum are readily recyclable materials, but improvement in recycling is necessary for many other materials throughout the ship. A key consideration is the design and installation of systems that prevent non-recyclable and/or hazardous materials from contaminating recyclable material.

Minimize Waste and Scrap
Much of the waste generated during construction can be reduced with careful production planning, weight control, and greater reliance upon detailed design and computer lofting of structure and piping systems.

To accomplish this analytic approach, state-of-the-art tools such as finite element analysis and computational fluid dynamics are used. At the pre-production and production stages of design, computer lofting is extensively used to plan for almost all of the structure of the ship, and increasingly in piping and wireways.

Maximize Use of Rapidly Renewable and Regional Materials
Rapidly renewable materials such as bamboo, linoleum, cork, poplar, and wool are generally accepted as having a natural replacement cycle of less than 10 years, so their use places less of a burden on our environment. Additionally, utilizing regional materials can reduce the energy required for their transport.

Minimize Air Emissions
Diesel engines that power a majority of the world’s fleet are responsible for carbon dioxide, sulfuric and nitrous oxides, smoke and particulate emissions, noise, and sensible heat leaving the stack. Positive change toward minimizing air emissions can lead to substantial environmental improvement. Areas for emission-minimizing opportunities include hull form optimization, speed considerations, diesel choices, and use of alternative fuels.

Minimize Energy Use
An often-overlooked aspect of the design is the location and placement of the appendages, such as the rudder, bilge keels, keel coolers, etc. If not aligned to the water flow over the hull, they can increase the drag by a surprising amount.


Increased hull and compartment insulation is another significant energy saver. HVAC requirements are typically the single-largest electrical load on ships. With the current high costs of fuel, the payback for better insulation can be measured in months. To maintain interior air quality, 20 percent or more of conditioned ventilation air is typically exchanged with fresh air from the outside. While this improves interior air quality, it also represents lost energy used to heat or cool the air. Much of this energy can be regained by installing fresh air heat exchangers, which heat or cool the incoming fresh air using the waste conditioned air it is replacing.

Much energy from fuel is lost as heat through the engine exhaust or for engine cooling. The ship designer can recover some of this lost energy by utilizing jacket water heat recovery to produce fresh water or for accommodation heating.

Photo: The harbor tug "ship docking module" design that is being adapted for hybrid drive. Photo courtesy of Elliott Bay Design Group.


For more information:
Full article and “Environmental Protection” edition of USCG Proceedings is available at http://www.uscg.mil/proceedings/Winter2008-09/.

Subscribe online at http://www.uscg.mil/proceedings/subscribe.asp.

Online survey available at: http://www.uscg.mil/proceedings/survey.asp.

Direct requests for print copies of this edition to: HQS-DG-NMCProceedings@uscg.mil.

Using Wind Power

Excerpt from U.S. Coast Guard “Proceedings of the Marine Safety & Security Council” magazine, by Mr. Stephan Brabeck, technical director, SkySails, GmbH & Co. KG.


In today’s environment, ship operating costs are skyrocketing, mainly due to rising oil prices and new international regulations for the reduction of ship emissions. In order to remain competitive, many shipping companies are looking for ways to minimize fuel consumption and emissions. One idea: Use wind power.

Two shipping companies, Beluga Shipping and Wessels Reederei GmbH & Co. KG, are testing one method using a large towing kite shaped like a paraglider to aid the propulsion of the vessel. The tethered, flying towing kites are designed to operate at altitudes between 100 and 300 meters, where stronger and more stable winds typically prevail. The Wessels vessel Michael A has been retrofitted with this system. MS Beluga SkySails hosts the first installation on a new build.

Taking advantage of the dynamic flight maneuvers this system is potentially capable of (such as figure-eights) could generate more power per square meter of sail area than conventional sails. It may be possible, then, to gain significant savings by using comparatively small sail areas.

System components are being long-term tested, and the results are continually used to improve and optimize the product. Research and development work will focus on advancing the technology and increasing its performance.

Early results indicate that while virtually all seagoing cargo vessels should be able to be retro- or outfitted with this propulsion, it is best suited for cargo ships with an average cruising speed of under 18 knots, as well as superyachts and fish trawlers of more than 24 meters.

For more information:
Full article and “Environmental Protection” edition of USCG Proceedings is available at http://www.uscg.mil/proceedings/Winter2008-09/.

Subscribe online at http://www.uscg.mil/proceedings/subscribe.asp.

Online survey available at: http://www.uscg.mil/proceedings/survey.asp.

Direct requests for print copies of this edition to: HQS-DG-NMCProceedings@uscg.mil.

Upcoming in Proceedings

Spring 2010: Rulemaking Update
• Rulemaking 101
• Interagency interaction
• Supporting analysis
• Public participation

Summer 2010: Maritime Domain Awareness
• Transforming MDA policy
• Transforming MDA capabilities
• Transforming MDA through technology

Fall 2010: Recreational Boating Safety


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