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Exemption and Equivalent Arrangements Under the International Convention on Load Lines, 1966, as Modified by the Protocol of 1988

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Coast Guard, DHS.

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Notice of issuance and availability.


The Coast Guard announces that it has recently notified the International Maritime Organization (IMO) of issuance of an exemption under the International Convention on Load Lines (ICLL) covering reduced “working freeboard” exemptions for hopper dredges. In addition, the Coast Guard announces completion and availability of the DR-68 reduced freeboard standards for hopper dredges. The Coast Guard also notified IMO of approved equivalent arrangements, as permitted by the ICLL and U.S. regulations, regarding hatch covers for hopper dredges and barges that meet “flooded hopper” stability criteria. This notice may be of special interest to the U.S. dredging industry and naval architecture, and marine engineering firms.


The Coast Guard issued formal notification to the IMO of equivalent arrangements for hatch covers for certain unmanned open hopper barges on March 30, 2009. We issued formal notification to the IMO of equivalent arrangements for hatch covers for certain manned, self-propelled open hopper dredges on November 12, 2009. We issued formal notification to the IMO of reduced freeboard exemptions for hopper dredges on April 7, 2010.


More information on load lines can be found on the Coast Guard load line website at:​hq/​cg5/​cg5212/​loadlines.asp. This notice, the IMO notifications, and DR-68 are available in the docket and can be viewed by going to, inserting USCG-2010-0618 in the “Keyword” box, and then clicking “Search.”

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Mr. Thomas Jordan, United States Coast Guard, Office of Design and Engineering Standards, Naval Architecture Division (CG-5212), at telephone 202-372-1370, or by e-mail at

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The International Convention on Load Lines (ICLL), 1966 is one of several international conventions administered by the IMO, a specialized agency of the United Nations. It was created to establish “uniform principles and rules with respect to the limits to which ships on international voyages may be [safely] loaded.” Chapter 51 (Load Lines) of Title 46 of the United States Code gives effect to ICLL provisions.

The most familiar load line feature is the well-known “Plimsoll mark” visible on each side of the hull. However, load lined vessels must also meet specific design and construction requirements. The purpose of load line assignment is to ensure the over-all seaworthiness of the intact (undamaged) vessel. Ocean service load lines allow unrestricted operations on any ocean, at any time of year (an extreme example being winter in the North Atlantic). This is accomplished by load line requirements that ensure: A robust hull that can withstand severe sea conditions, the weathertight and watertight integrity of critical openings, sufficient reserve buoyancy and freeboard, and accurate stability and loading information provided on board.

To that effect, the ICLL prescribes 44 regulations that pertain to the design and construction of a ship, an additional five regulations specifically for vessels that carry timber deck cargoes, and seven regulations that divide the oceans into zones and areas on the basis of seasonal weather criteria. The United States regulations for a domestic ocean service load line (in 46 CFR Part 42) implement Chapter 51 of Title 46 of the United States Code.

United States and ICLL Regulations

As stipulated in 46 CFR 42.03-5, most commercial United States vessels more than 79 feet long that operate outside the Boundary Line are required to have a load line assignment. Those United States vessels that go on voyages to foreign ports must have an international load line assignment issued in accordance with the ICLL. United States vessels that operate outside the Boundary Line on domestic voyages only (i.e., coastwise, Great Lakes, or ocean voyages that return directly to a U.S. port) must have a domestic United States load line assignment.

Although most domestic and ICLL load line requirements are appropriate for laden cargo ships on the high seas, some of the requirements can be overly conservative—and burdensome—for certain service vessels that operate nearshore under less-severe conditions. However, under the ICLL and 46 CFR 42.03-20 and 42.03-30, it is possible to relax those requirements—or exempt them entirely—if the vessel is still able to maintain the equivalent level of safety intended by load line assignment.

Exemption and Equivalency Authority Under the ICLL and United States Law

Recognizing the wide variety of commercial vessel types and realizing that not every regulation is necessarily appropriate for every vessel design, the ICLL includes provisions that give Administrations (signatory member nations) some degree of flexibility in applying the regulations to vessels of unusual form or service. In addition, 46 U.S.C. 5108 (“Special Exemptions”) permits exemption of a vessel from the load lines requirements when “(1) the vessel is entitled to an exemption under an international agreement to which the United States is a party; or (2) under regulations (including regulations on special operations conditions) prescribed by the Secretary, the Secretary finds that good cause exists for granting an exemption.” When an exemption is granted, a certificate of exemption may be issued.

Exemptions: Both ICLL Article 6(2) and 46 CFR 42.03-30 authorize the exemption of any vessel which embodies features of a novel kind from load lines requirements that might impede research and development of such novel features. Under both provisions, however, the relevant authority is required to ensure the over-all safety of the vessel for the service intended.

Equivalents: Both ICLL Article 8 and 46 CFR 42.03-20 allow the approval of any alternative fitting, material, appliance, apparatus, or other provision, provided that the alternative is as effective as that required by the Convention.

IMO Notification: When approving an exemption or equivalency under the authority of either Article 6(2) or 8, the Administration is required to submit a notification to IMO, describing the issue, the reasons for the Administration's decision, and the alternative arrangement that was approved (if applicable). IMO then circulates the notification among all member Administrations for their information.

ICLL Exemptions for Hopper Dredges: Reduced Freeboards

The Coast Guard has recently approved reduced freeboard exemptions for some United States dredges under two special load line regimes: (1) “working freeboard” and 2) DR67.

“Working Freeboard”

With few exceptions, vessels are prohibited from submersion of their load line marks. This prevents overloading and maintains sufficient freeboard and reserve buoyancy for the high seas voyage. However, it is not possible for hopper dredges to conduct dredging operations under the extreme weather conditions anticipated by the load line regulations. Furthermore, unlike cargo ships, hopper dredges have Start Printed Page 62562the unique ability to quickly jettison their spoils cargo and regain thousands of tons of buoyancy. Therefore, the full freeboard for unrestricted ocean operation is unnecessary during dredging operations. Permitting the dredge to operate at a reduced freeboard (i.e., to submerge its marks) under relatively benign weather conditions allows it to safely carry more spoils per run, thereby increasing its efficiency. Based on that consideration, there are two special reduced freeboard exemption regimes that have been developed for qualified hopper dredges.

The first regime was established in 1989 for United States dredges operating in domestic waters, when the Coast Guard promulgated the “working freeboard” load line regulations in 46 CFR 44.300 through 44.340. In order to qualify for the reduced “working freeboard” assignment, a dredge must meet several design and equipment requirements: intact and two-compartment damage stability, remote draft indicators, ability to jettison spoils under emergency conditions, etc. When dredging at the reduced freeboard, it is operationally restricted to locations within 20 nautical miles from a place of refuge, seas not exceeding 10 feet and winds not exceeding 35 knots. Under these conditions, the dredge can be assigned a reduced “working freeboard” of 50% of its normal freeboard assignment.

Several United States hopper dredges have qualified for this domestic “working freeboard” assignment over the 20 years that the regime has been in existence. The Coast Guard has now reviewed this domestic regime and determined that it is equally suitable for international service. For purposes of ICLL assignment, dredges that meet the “working freeboard” criteria of 46 CFR 44.300 embody “novel features” as contemplated by ICLL Article 6(2) (discussed above). When operated in conjunction with appropriate weather restrictions, they may safely operate at the reduced freeboard. Therefore, in accordance with the ICLL Article 6(2) and 46 CFR 42.03-30, and on a case-by-case basis, the Coast Guard will authorize an ICLL Exemption Certificate that exempts the dredges from ICLL Article 12, which otherwise prohibits submersion of the load line marks.

DR-67 and DR-68

The second reduced freeboard regime for hopper dredges was established in 2001 by a joint European working group of classification societies, the dredging industry, the shipbuilding industry, and regulatory officials from Belgium, France, Germany, the Netherlands, and the United Kingdom. Their exemption regime is titled “Guidelines for the Construction and Operation of Dredges Assigned Reduced Freeboards,” but is generally referred to as “DR-67.” Like the United States “working freeboard” regime, DR-67 sets out similar design and equipment requirements. However, DR-67 differs from the United States regime in that it is more flexible in its weather restrictions, and can allow up to a 66% reduction in freeboard under sufficiently benign conditions.

The European working group has revised and updated DR-67; the new revision is referred to as “DR-68.” The Coast Guard participated in this revision effort to ensure that DR-68 is consistent with United States safety concerns and in order to provide United States dredge operators with an alternative approach for reduced freeboard assignment. Therefore, in accordance with the ICLL Article 6(2) and 46 CFR 42.03-30, and on a case-by-case basis, the Coast Guard will authorize an ICLL Exemption Certificate that exempts the dredges from ICLL Article 12, which otherwise prohibits submersion of the load line marks.

ICLL Equivalents for Hopper Dredges and Barges: Hatch Covers

Ordinarily, load line regulations require hatch openings to be closed by weathertight hatch covers, since conventional cargo ships cannot survive extensive flooding of their cargo holds. However, some open hopper vessels (such as dredges, dump scows, etc.) can be designed to maintain adequate buoyancy and stability even with flooded hoppers. For such vessels, this stability characteristic provides an equivalent level of safety to the hatch covers; therefore, hatch covers are unnecessary and may actually interfere with other aspects of the vessel design.

In accordance with the ICLL Article 8 and 46 CFR 42.03-20, the Coast Guard will, on a case-by-case basis, approve equivalent arrangements from ICLL Regulation 14 (requirement for hatch covers).

Coast Guard Notifications to IMO

As required by the Convention, the Coast Guard has already submitted the requisite notifications to IMO. These documents, as well as copies of DR-67 and DR-68, are posted on-line at: (docket ID number USCG-2010-0618).

Requesting Exemptions and Equivalencies

Owners/operators of hopper dredges or barges desiring an exemption or equivalency using any of the above three standards should contact their load line issuing authority (classification society), who will review the vessel for compliance with the Coast Guard's criteria for the exemption or equivalency. The classification society will then make a recommendation to the Coast Guard Naval Architecture Division (CG-5212) for approval. The mailing address is Commandant (CG-5212), U.S. Coast Guard, 2100 2nd Street, SW., Stop 7126, Washington, DC 20593-7126.

This notice is issued under authority of 5 U.S.C. 552 and 46 U.S.C. 5108.

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Dated: September 15, 2010.

J.G. Lantz,

Director, Office of Commercial Regulations and Standards, U.S. Coast Guard.

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[FR Doc. 2010-25500 Filed 10-8-10; 8:45 am]