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From page 128... ... 128 APPENDIX H WEIGHT GROWTH IN PASSENGER VESSELS International Maritime Response to Weight Growth and Lightship Verification Schemes International Regulations Because of the potentially negative impacts that weight growth (or weight creep) can have on a ship's stability, many maritime nations have mandated lightship verification schemes for various classes of vessels. Read the entire page →
From page 129... ... 129 A majority of the regulations listed use a verification scheme that involves a periodic lightship deadweight survey on a 5-year interval. Other forms of lightship verification include a weight tracking program, the use of lightship verification freeboards, or a declaration by the owner that either no changes or only minor changes have occurred to the vessel's lightship. Read the entire page →
From page 130... ... 130 with simple outfitting, such as charter fishing vessels or excursion-only passenger vessels with only basic food service. The written declaration is currently used in the following maritime regulations as an option for periodic lightship verification:  Canada, Transport Canada, Passenger Vessels less than 24 Meters Long  UK, MSN, Vessels Subject to Stability Heel Test Weight Tracking Program Lightship Verification Scheme The basic weight tracking program consists of the owner or master recording the changes made to the vessel after the vessel's initial inclining. Read the entire page →
From page 131... ... 131 Several important factors would need to be considered when developing a weighttracking program for a specific vessel. The first is how small a weight change must be included. Read the entire page →
From page 132... ... 132 stability test data. For example, fuel could be at 50% and water tanks, pressed full, and sewage at 25%. Read the entire page →
From page 133... ... 133 lightship verification loading condition as described above. This method does require the taking of a series of freeboards as opposed to just looking at a set of physical marks. Read the entire page →
From page 134... ... 134 to be different from the density at the time of periodic checks where the vessel operates. Two, the vessel may operate at different locations throughout its life, which could have significantly different water densities. Read the entire page →
From page 135... ... 135 2. The results would not only tell if the lightship condition has changed, but also by how much the lightship has actually changed. Read the entire page →
From page 136... ... 136 involves the slow increase in a vessel's weight from the accumulation of many small changes or the onboard accumulation of parts that may occur over time. Usually the first two sources of weight growth are readily apparent and would require a full stability review by attendant regulatory authorities. Read the entire page →
From page 137... ... 137 chairs by just 10 lbs apiece and the tables by 30 lbs apiece results in a weight growth of 3,500 lbs. On the surface, this change appears to be a small and insignificant one, particularly on a vessel that would have a lightship weight of approximately 250 long tons (560,000 lbs) Read the entire page →
From page 138... ... 138 The notional weight growth to be added to the vessel for this example would be based on the vessel's lightship weight, because a percentage increase in lightship weight is one of the triggers for determining if a vessel must undergo an additional stability review. To capture a vessel's sensitivity to weight growth, a possible range for the weight growth for this example is 0.25% to 6%. Read the entire page →
From page 139... ... 139 The weight growth was added at the approximate vertical and longitudinal center (see Figure H-1) of the passenger spaces above the main deck as this is where most of the weight growth will likely occur. Read the entire page →
From page 140... ... 140 Table H-1 Effect of Weight Growth on the Vessel's Midships Draft Midship's Increase in Percent Increase Condition Draft -- Feet Midships Draft from Baseline (BL) Baseline 8.28 -- -- +2% Growth 8.39 1-3/8" +1.3% +4% Growth 8.50 2-5/8" +2.7% +6% Growth 8.61 4" +4.0% This small change in draft is not likely to be noticed by the crew or the USCG OCMI, and with the same weight growth rate over 10 or 15 years, it is unlikely this increase in draft would be noticed either. Read the entire page →
From page 141... ... 141 The reduction in area under the GZ curve is very significant as the weight growth enters the 4% to 6% range (see Table H-4) Read the entire page →
From page 142... ... 142 growth was at 6%. In addition, this failure was only in the required downflooding angle just going below the 15-degree minimum (14.9 degrees) Read the entire page →
From page 143... ... 143 Table H-6 Summary Results from Sensitivity Study of the Impact of Lightship Weight Growth on the Intact Stability of a Small Passenger Vessel Read the entire page →

From page 128...

... 128 APPENDIX H WEIGHT GROWTH IN PASSENGER VESSELS International Maritime Response to Weight Growth and Lightship Verification Schemes International Regulations Because of the potentially negative impacts that weight growth (or weight creep) can have on a ship's stability, many maritime nations have mandated lightship verification schemes for various classes of vessels.