My next project - 12m passanger river vessel

[micspoko]

The vessel will be built under the supervision of a classification society and will have a limited number of people

[Ike]

The USCG used 140 lb until the Ethan Allen case. The last figure I saw in USCG documents is now 184 lb. And there have been other changes made.

Here's part of an article I wrote about this last year;

On a commercial vessel, the number of passengers is estimated based on the lesser of the following criteria:

1. Length of rail: one passenger for each 30 inches of rail at the sides and stern., or,

2. The deck area; one passenger per 10 square feet of deck area, excluding spaces listed in 46 CFR 176.113, which include, among other areas, concession stands, toilets, lifesaving gear storage spaces, required aisle area, or

3. The fixed seating areas, or fixed seating; one passenger for each 18 inches of fixed seating width.

The stability of the vessel is then determined using the number of passengers allowed based on the initial determination. An SST (simplified stability test) is conducted, based on the Coast Guard criteria of 140 pounds per person. If the boat does not pass the stability test then the number of passengers is based on the weight of passengers that would pass the test at 140 lbs per passenger. The Ethan Allen investigation has determined that this weight is too low, and should be at least 174 pounds. The Coast Guard has raised it to 184.

The capacity is based on stability because on larger boats the displacement weight is so great as to create an unrealistic amount of passenger weight that could be carried. But, passenger weight and placement has a significant effect on the stability. Capsize is the issue. Capsize leads to sinking. Especially, if as in the case of the Ethan Allen, the boat is near its limits of stability and the passenger load suddenly shifts to one side.

http://newboatbuilders.com/docs/safeloading.pdf


Some links on Etahn Allen
NTSB News report on Ethan Allen http://www.ntsb.gov/pressrel/2006/060725.htm
The NTSB Report http://www.ntsb.gov/Publictn/M_Acc.htm)
Popular Mechanics Article on the Accident: http://www.popularmechanics.com/outd...g/4199636.html
BoatUS on FindArticles.com http://findarticles.com/p/articles/m...1/ai_n16019364

However, I agree that the designer needs to do a complete stability analysis of the loading for this boat, especailly for loads on the upper deck.