Auto Closing Air Vent As Downflooding Point

DEAR FRIENDS
Shall i consider "AUTO CLOSING AIR VENT" on weather deck as down-flooding point while stability calculation?

 

The problem is not whether or not self-closing. Any opening, if it has not a watertight seal, must be considered as a down-flooding point.

 

what about weather tight doors on upper deck?

 

These links may help you
http://www.mared.org/
http://www.dft.gov.uk/mca/mcga-mnotice.htm?textobjid=30C1EF4CA65B3EAB

 

Any opening, not watertight sealed, is a posible down-flooding point.
For very small openings, according to the Administration, you can request an exception to this rule.

 

This is what regulation says.........

"Downflooding angle is an angle of heel at which openings in the hull, superstructures or deckhouses which cannot be closed weathertight immerse. In applying this criterion, small openings through which progressive flooding cannot take place need not be considered as open...."

 

small openings through which progressive flooding can take place need to be considered as open...

 

It depends what you are calculating. For ships designed according to SOLAS:

When calculating probabilistic damage stability - automatic self closing air vents are considered as down-flooding points.
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When calculating intact stability only unprotected openings need to be considered as downflooding points.
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Exceptions are sometimes made by flag states concerning the watertightness of a ball-type automatic closing air vent, if it has a certificate proving it is watertight at a continuous water column for a sustained amount of time. Example of this is the dutch flag which will allow some of these vents to be considered watertight.

 

What about "Exhaust gas pipes openning" shall i consider them as downflooding point?If water goes inside exhaust gas pipes, then water would stop at engine and water can not fill engine room.

 

And if the engine is running?

 

You cannot assume that. There are some crank/valve positions (overlap) which would allow water to pass thru cylinders and intake and cause flooding. Or even leak down past rings and flood the crankcase, albeit slowly.

 

if water can pass through those fittings then smoke also can leak into the engine room.but we don't have smoke leakage in the engine room.

 

Thats not how that works lol.

 

Extract from IMO Code on Intact Stability:

 

Somewhere along the rules, there is a definition for "weathertight" and "watertight". It seems to be used interchangeably in this thread. Would somebody care to explain?