Stability Letter

[bobozr]

When the CG decided to weigh divers in 2011, they cut us back by two divers. Shortly after that they cut us by two more. While the average Diver weight remains at the new number of 185, they used 120 lbs for the gear, in addition. The original stability test and the adjusted letter used 80 lbs for equipment, hence the difference in overall weight. My question is: Does anyone have a reference for the 120Lb figure? The 46CFR 178.330 a (4) (v) is the only reference I can find and it still shows 80lbs for equipment.
I am getting my stuff together to try to regain a seat or two, and it would help to be able to find references to cite.

 

[Wookie]

On my stability letter, and in the stability instructions, you are supposed to add 1/2 of the weight of a diver for gear. It is not supposed to be a set weight.

Assuming your vessel is less than 65 feet in length, perform a simplified stability test. It’s far less cost than an inclining experiment, and if you’re smart enough to read the instructions, you’re smart enough to perform the test.

The CG must witness the test, and approve your calculations for your experiment.

Then you can have all of your passengers back.

 

[bobozr]

Thanks for the response, but that is an entirely new direction. I have not been able to find any reference that gives a number other than 80 lbs for gear. I cannot find anything that gives 1/2 the diver's weight or 120 lbs either. The standard weight given for passenger weight is now 185 lbs so 1/2 of that would be 92.5. When the boat was first certified, the stability letter gave us 20 divers and crew and 28 passengers and crew. That was done using 160 lbs per passenger and 80 lbs for dive equipment. Now our latest stability letter makes no mention of passengers at all. I know that searches of the Federal Register and other legal sites can produce varying results, I just want to find the latest numbers.

 

[Wookie]

49 CFR 178.330 a (4) v. It’s in the simplified stability test.

(v) If the vessel carries passengers on diving excursions, the total weight of diving gear must be included in the loaded condition and placed in its stowed position. Not less than 80 pounds (36.3 kilograms) should be assumed for each person for whom diving gear is provided.

Sounds like you have a young inspector out to prove something to you. So, if he insists on 120, appeal to the OCMI. Inspectors, and especially new inspectors must be slapped occasionally so they don’t get too big for their britches.

Respectfully, of course.

And I’ve never heard of a COI that doesn’t limit the number of passengers you can carry based on the stability letter. Every stability letter I’ve ever seen has number of passengers, limitation for divers, and cargo carriage requirements. Mine also had other conditions, including max draft fore and aft as read on the draft marks. Vessels under 65’ who do simplified stability don’t have draft marks. Additionally, I had a plimsoll mark as a part of my load line. That was reflected in the stability letter. My latest stability letter was issued in 2015.

 

[bobozr]

Thanks for the replies. The weights cited in the simplified stability test are the only actual published numbers, I can find. I still haven't found any reference to half the diver's weights. As we all know, while divers have gotten fatter (heavier) the equipment has actually become lighter and more streamlined. The larger steel tanks may weigh more than aluminum, but that is a wash due to the reduced additional weights needed for neutral buoyancy. I have a lot of experience with the government as a retired civil servant, but trying to argue restrictions due to arbitrary numbers has me buffaloed. If any of you could let me know what your stability letters state as regards divers equipment weights. Mine specifically states 95 lbs per diver. If yours states something different, I would love to know. I will hold all answers in confidence. I only want to see how arbitrary the numbers get.

 

[Wookie]

My wife says it’s on an old COI circa 1990. I will look, those records aren’t scanned.