6.16.1
Intended use. The deck cargo barge is intended for use as a utility barge in harbors and rivers and for transporting vehicles such as medium tanks and 2-1/2-ton trucks to and from ship to shore. It is intended that the barge structure will be of sufficient stength for towing overseas in light condition.
vi. Het ‘technical manual’ voor ‘watercraft equipment’ bevat voor een ‘barge, deck cargo, non-propelled, ocean towing, 585 Tons, Design 231A’, de volgende omschrijving:
“PURPOSE: to transport wheeled and tracked vehicles and general cargo in harbors and in[l]and waters.
TRANSPORTABILITY: Can be towed to overseas destination.”
(…)
HULL AND ACCOMMODATIONS DATA:
Construction: Steel. This barge is equipped with two skegs aft, making it suitable for towing with a minimum of yawing.
vii. In zijn ‘Opinion on Operating Characteristics Design’ geeft Rik F. van Hemmen, President en senior partner van Martin, Ottoway, van Hemmen & Dolan Inc., onder het kopje ‘barge description’ onder meer de hiervoor onder ii onder 6 en onder iii gegeven omschrijvingen weer. Onder het kopje ‘Technical discussion’ wordt vervolgens het volgende vermeld:
Based on our review of the information, the specification describes its intended use: “Mainly in harbors and river and for ship to shore duties and for overseas towing in light condition.”
This specification states that the barge’s intended service is for coastal (ship to shore) and river service but needs to have sufficient strength to be towed overseas.
As such, its design needs to conform to ocean going strength requirements since design to a lesser strength would not make it possible for the vessel to be towed overseas in light condition.
(…)
In US barge construction, primarily the weld design positively establishes ocean service. (…).
Furthermore (…) the side longitudinal stiffener welds are generally 4 inch staggered welds at 12 inch spacing. This weld specification is in excess of ocean going rules where the 1948 rules required 3 inch staggered welds at 12 inch spacing.
(…)
The term “”light condition” is not defined in the specification. Traditionally light condition means without cargo. However, with respect to the subject specification and towed barges, ligth condition may have a slightly different definition.
It is noted that the subject barge has a designed full load draft of 8 feet, which would leave a freeboard of only 2 feet when fully loaded. A freeboard like this on a barge would result in a variety of technical problems when the barge operates in ocean waves. At the same time a 2 foot draft (and 8 foot freeboard) can easily result in slamming and cause windage problems when under tow.
In practice, on an ocean transit, a barge like this is more reasonably towed at a draft of 4 or 5 feet with a slight trim by the stern.
(…)
US naval architects do not use the term sea (zee) except to note that seas are smaller oceans and therefore the vessel may not reasonably be designed and constructed to withstand full and continuous ocean conditions, but can still primarily operate in the sea.
In the United States, operation in the sea is generally described as “coastal voyages” or “partially protected voyages.” These operations are in the sea (…) and generally allow reduced vessel strength and stability characteristics under the assumption that the vessel can reach a port of refuge or that wave and weather conditions will not exceed a certain maximum. Therefore “drijven in zee” in United States Naval Architectural custom is a lower standard that needs to be judged on a voyage by voyage basis.
If one were to evaluate the subject vessel to judge whether its design and construction is solely or primarily for floatation in coastal and partially protected voyages (de zee), there is no doubt that its design and construction responds exactly to that use.”
viii. Michael Minnig, directeur van de afdeling Engineering van Foss Maritime Company, schrijft in zijn ‘technical memo’ onder meer het volgende:
“The MIL-B-10527 stated exception of towing the bage overseas in a light condition is documented allowance for the limited overseas transit of the barge as a secondary mission for relocation without cargo between operational harbors. This exception is the only location where the use of the word “sea” is mentioned (…).
The term “sea” has a general definition in predominant published regulatory design rules where, when used, is intended to be synonymous with ocean or offshore service.
4. As stated (…) Reference 2 requires welding to conform to ABS Offshore Barge Rules. (…).
With the barge needing to transit in light condition for relocation purposes and the ABS River Rules being minimum requirements, the requirement for welding to conform to ABS Offshore Barge Rules appears prudent. However, this welding requirement is not an excessive requirement for a harbor craft and does nog define or express design intent.”
en, met betrekking tot het rapport van Van Hemmen:
“This perspective of a 120’x33’x10’ barge being more intend for harbor use is reinforced by Mr. van Hemmen’s own statements on page 6:
“It is noted that the subject barge has a designed full load draft of 8 feet, which would leave a freeboard of only 2 feet when fully loaded. A freeboard like this on a barge would result in a variety of technical problems when the barge operates in ocean waves. At the same time a 2 foot draft (and 8 foot freeboard) can easily result in slamming and cause windage problems when under tow.”
As he points out, the use of such a barge does not suit an unrestricted or sea going service in either the fully loaded or light conditions. The letter continues with:
“in practice, on an ocean transit, a barge like this is more reasonably towed at a draft of 4 or 5 feet with a slight trim by the stern.”
This statements communicates that the barge design slould only be considered for ocean towing given a very specific cargo weight and draft. This limitation does not reflect an overall intended design purpose, but rather a very exclusive loading condition to be adhered to for ocean use.
(…)
Mr. van Hemmen attempts to quote MIL-B-10527C by stating: “Mainly in harbors and river and for ship to shore duties and for overseas towing in light condition.” The use of the word “mainly” never appears in MIL-B-10527C.
(…)
(…) Mr. van Hemmen states: “In US barge construction, primarily the weld design positively establishes ocean service”. This statement is contrary to an earlier statement of his which says: “a driving factor for ocean going barges is bending strength”. Bending strength is dictated by the barge’s cross sectional structural arrangement and not the welds attaching those members together. Utimately, desired deck cargo loading, barge hull proportions, and its longitudinal strength establishes its intended service. Weld lengths/sizes are byproducts of the selected design scantlings, their thicknesses, and spacing.”
“(…) [T]his memo provide[s] documented requirements which identify the primary operating service of Design 231A as a harbor barge. Only exemptions and secondary relocation needs consider any sea going allowances of the barge operation. ”