Worst Case Scenario: Hitting A Sunken Container - What To Do!??

[Group9]

Originally Posted by goboatingnow

slowing down at night !, huh, I mean going from 7 kn to 5 kn isn't going to make any difference anyway, given the momentum

dave

Well, then don't slow down at night if you think the laws of physics don't apply to your boat.

[boatman61]

Originally Posted by Group9

Well, then don't slow down at night if you think the laws of physics don't apply to your boat.

Standard practice on my boats at night on passage... reef the main right down and furl 1/3rd of the genoa at sunset...
Covers several eventualities for the hours of darkness...

[Mr B]

I have enough Genoa out to maintain about 3 knots, I lower the windward side centre board, and drop the drive leg into the water to act as a drogue,

With out that windward side Centre Board down, It does tend to flick sideways, Beam on, Which can get quite hairy at times,

It might have some thing to do with the 600 mm Draught, Hahahaha, Yes, I did say, Two feet, I sit on top of the water, Not in it,

I have a comfortable night, Running in front of the sea, I just make sure I have 30 NMiles of clear ocean in front of me,

At 3 knots, Hopefully I would slide over any thing at sea, As you pass over, the object would also sink or be pushed away from you, ( 30,000 posts on the IF's of that one )

Coral reef, At 3 knots, will Slice a big hole in you, Possibly about three feet long for a four ton boat, By the time it stops,

Unfortunately, A Mono hull will probably fall over on its side, For those inside, It would be sheer terror, A big, very loud tearing sound, the boat thrown violently sideways, Buried in what ever was loose, Any one on deck, Possibly over the side,

Fiji, goes from 10000 feet deep to 66 feet in 10 feet, Thats when there is a gap in the reef,

Vanuatu, Efate, Goes from 600 feet deep to a 6 foot embankment above the water in about 5 feet, Thats a channel inside the islands. I parked on a small ledge that had 20 feet of water,

Outside it runs 34 feet deep and then 10000 feet again, These Island countrys have vertical walls around them,

[Mr B]

The one question that needs to be answered by every one of you that sails further than the end of the dock,

Will your boat sink, if it does get a big hole in it,

[Oliver L.]

Brian,

on my boat the water tanks are the stub keels of the hulls, so they are definitely not going to start anything funny.

Also, I am led to believe that my boat won't sink if holed, because of the amount of Balso wood between the inner and outer layer. Have I tried it? Nope. Do I want to try? Ditto - but it still gives me a warm feeling.

Oliver

[David_Old_Jersey]

Originally Posted by Mr B

The one question that needs to be answered by every one of you that sails further than the end of the dock,

Will your boat sink, if it does get a big hole in it,

They all sink, if the hole is big enough..........and it can always be big enough.

The difference is that some leave a bit more flotsam, and some think that is still called a boat .


Personally I think entirely prudent to at least consider the possibility of sinking (no matter what the brochure may say, or imply), if "you" think it is likely then the best tactic is not to go ......and entirely deluded if "you" think it can never happen, or that it won't sting a bit .

What "you" do about that possibility is own judgement call and will depend on boat, voyage plans and personal risk profile (and that likely affected by whether others on board - and how much you like 'em ).

If voyaging on small boats was 100% "Safe", then Disney would also make boats...........

[boatman61]

Originally Posted by David_Old_Jersey

They all sink, if the hole is big enough..........and it can always be big enough.

The difference is that some leave a bit more flotsam, and some think that is still called a boat .


Personally I think entirely prudent to at least consider the possibility of sinking (no matter what the brochure may say, or imply), if "you" think it is likely then the best tactic is not to go ......and entirely deluded if "you" think it can never happen, or that it won't sting a bit .

What "you" do about that possibility is own judgement call and will depend on boat, voyage plans and personal risk profile (and that likely affected by whether others on board - and much you like 'em ).

If voyaging on small boats was 100% "Safe", then Disney would also make boats...........

They do... and they can be sailed and docked submerged... see 'Pirates of the Caribbean'...

[captain58sailin]

That was one of the greatest sailing scenes ever.

[Rakuflames]

Originally Posted by transmitterdan

Divers have to add air to stop sinking. There is nothing like that in a container. Once a container gets awash it will keep going down barring some peculiar automatic inflating device inside. Even then it would rise to the surface. No way it will hover in the water column like a diver can.

They will however, not always immediately sink like a stone. Some of them will first have to fill up with water.

So it really is possible to see one partially submerged, or "floating" just below the water line. It can happen.

I'm glad most of them are at the bottom, depending on what toxic stuff they might hold.

[Rakuflames]

Originally Posted by Oliver L.

Brian,

on my boat the water tanks are the stub keels of the hulls, so they are definitely not going to start anything funny.

Also, I am led to believe that my boat won't sink if holed, because of the amount of Balso wood between the inner and outer layer. Have I tried it? Nope. Do I want to try? Ditto - but it still gives me a warm feeling.

Oliver

Yeah I heard that about a cruise ship once -- around 1912, I think ...

[Mr B]

Originally Posted by Rakuflames

Yeah I heard that about a cruise ship once -- around 1912, I think ...

And if they hadnt cheated with the Bulkheads, It would not have sunk either,

[transmitterdan]

Originally Posted by Rakuflames

So it really is possible to see one partially submerged, or "floating" just below the water line. It can happen.

Partially submerged is possible. Floating with a tiny bit above the water line is possible. A container floating just below the water line is impossible. As soon as it can no longer float an inanimate object sinks unless something acts to add bouncy.

[goboatingnow]

Originally Posted by boatman61

Standard practice on my boats at night on passage... reef the main right down and furl 1/3rd of the genoa at sunset...
Covers several eventualities for the hours of darkness...

I agree , I reduce sail at night , I was merely commenting that hitting a container at 5 knots or 7 knots ain't going to make a lot of difference

Da d

[goboatingnow]

Originally Posted by transmitterdan

Partially submerged is possible. Floating with a tiny bit above the water line is possible. A container floating just below the water line is impossible. As soon as it can no longer float an inanimate object sinks unless something acts to add bouncy.

What about neutral buoyancy then !

Dave

[transmitterdan]

Originally Posted by goboatingnow

What about neutral buoyancy then !

Dave

Neutral buoyancy is an unstable state by definition and requires intervention to be maintained for any length of time and 99.9999% of the time a neutrally buoyant object at the surface sinks. Since it has no buoyancy system a container cannot be "neutrally buoyant" for very long. Either it floats or it sinks. There is no stable middle point.

Assume the container is neutral at the surface and it is sitting with the entire thing submerged but not sinking. The first wave that comes along will wash over it. This will increase the pressure on the contents and they will compress slightly becoming less buoyant and the whole thing starts going down. The further it drops the higher the pressure and the faster it sinks. It is now on a one way trip to the bottom.

The odds would be like winning the lottery for a container to sit completely submerged but not sink. We are being pedantic though so I'll leave this issue alone from now.

A container that is 90% submerged is a real possibility and a real danger. I don't know how common that is but my guess is not very. Most containers are packed with a significant amount of air inside. When that air is displaced by water they will usually sink. Very few containers are 100% air tight.